diff options
| author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2017-01-04 11:34:01 +0100 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2017-01-04 11:35:18 +0100 |
| commit | a402eae64d0ad12b1c4a411f250d6c161e67f623 (patch) | |
| tree | 8c031c914e29321c01b94497a0f9c49ee6b03dc4 /Documentation/admin-guide | |
| parent | 7800fb69ddf3a13d2055009c87eacf7f46f907c8 (diff) | |
| parent | 0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff) | |
Merge tag 'v4.10-rc2' into drm-intel-next-queued
Backmerge Linux 4.10-rc2 to resync with our -fixes cherry-picks. I've
done the backmerge directly because Dave is on vacation.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Diffstat (limited to 'Documentation/admin-guide')
29 files changed, 14120 insertions, 0 deletions
diff --git a/Documentation/admin-guide/README.rst b/Documentation/admin-guide/README.rst new file mode 100644 index 000000000000..1b6dfb2b3adb --- /dev/null +++ b/Documentation/admin-guide/README.rst @@ -0,0 +1,411 @@ +Linux kernel release 4.x <http://kernel.org/> +============================================= + +These are the release notes for Linux version 4. Read them carefully, +as they tell you what this is all about, explain how to install the +kernel, and what to do if something goes wrong. + +What is Linux? +-------------- + + Linux is a clone of the operating system Unix, written from scratch by + Linus Torvalds with assistance from a loosely-knit team of hackers across + the Net. It aims towards POSIX and Single UNIX Specification compliance. + + It has all the features you would expect in a modern fully-fledged Unix, + including true multitasking, virtual memory, shared libraries, demand + loading, shared copy-on-write executables, proper memory management, + and multistack networking including IPv4 and IPv6. + + It is distributed under the GNU General Public License - see the + accompanying COPYING file for more details. + +On what hardware does it run? +----------------------------- + + Although originally developed first for 32-bit x86-based PCs (386 or higher), + today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and + UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell, + IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS, + Xtensa, Tilera TILE, AVR32, ARC and Renesas M32R architectures. + + Linux is easily portable to most general-purpose 32- or 64-bit architectures + as long as they have a paged memory management unit (PMMU) and a port of the + GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has + also been ported to a number of architectures without a PMMU, although + functionality is then obviously somewhat limited. + Linux has also been ported to itself. You can now run the kernel as a + userspace application - this is called UserMode Linux (UML). + +Documentation +------------- + + - There is a lot of documentation available both in electronic form on + the Internet and in books, both Linux-specific and pertaining to + general UNIX questions. I'd recommend looking into the documentation + subdirectories on any Linux FTP site for the LDP (Linux Documentation + Project) books. This README is not meant to be documentation on the + system: there are much better sources available. + + - There are various README files in the Documentation/ subdirectory: + these typically contain kernel-specific installation notes for some + drivers for example. See Documentation/00-INDEX for a list of what + is contained in each file. Please read the + :ref:`Documentation/process/changes.rst <changes>` file, as it + contains information about the problems, which may result by upgrading + your kernel. + + - The Documentation/DocBook/ subdirectory contains several guides for + kernel developers and users. These guides can be rendered in a + number of formats: PostScript (.ps), PDF, HTML, & man-pages, among others. + After installation, ``make psdocs``, ``make pdfdocs``, ``make htmldocs``, + or ``make mandocs`` will render the documentation in the requested format. + +Installing the kernel source +---------------------------- + + - If you install the full sources, put the kernel tarball in a + directory where you have permissions (e.g. your home directory) and + unpack it:: + + xz -cd linux-4.X.tar.xz | tar xvf - + + Replace "X" with the version number of the latest kernel. + + Do NOT use the /usr/src/linux area! This area has a (usually + incomplete) set of kernel headers that are used by the library header + files. They should match the library, and not get messed up by + whatever the kernel-du-jour happens to be. + + - You can also upgrade between 4.x releases by patching. Patches are + distributed in the xz format. To install by patching, get all the + newer patch files, enter the top level directory of the kernel source + (linux-4.X) and execute:: + + xz -cd ../patch-4.x.xz | patch -p1 + + Replace "x" for all versions bigger than the version "X" of your current + source tree, **in_order**, and you should be ok. You may want to remove + the backup files (some-file-name~ or some-file-name.orig), and make sure + that there are no failed patches (some-file-name# or some-file-name.rej). + If there are, either you or I have made a mistake. + + Unlike patches for the 4.x kernels, patches for the 4.x.y kernels + (also known as the -stable kernels) are not incremental but instead apply + directly to the base 4.x kernel. For example, if your base kernel is 4.0 + and you want to apply the 4.0.3 patch, you must not first apply the 4.0.1 + and 4.0.2 patches. Similarly, if you are running kernel version 4.0.2 and + want to jump to 4.0.3, you must first reverse the 4.0.2 patch (that is, + patch -R) **before** applying the 4.0.3 patch. You can read more on this in + :ref:`Documentation/process/applying-patches.rst <applying_patches>`. + + Alternatively, the script patch-kernel can be used to automate this + process. It determines the current kernel version and applies any + patches found:: + + linux/scripts/patch-kernel linux + + The first argument in the command above is the location of the + kernel source. Patches are applied from the current directory, but + an alternative directory can be specified as the second argument. + + - Make sure you have no stale .o files and dependencies lying around:: + + cd linux + make mrproper + + You should now have the sources correctly installed. + +Software requirements +--------------------- + + Compiling and running the 4.x kernels requires up-to-date + versions of various software packages. Consult + :ref:`Documentation/process/changes.rst <changes>` for the minimum version numbers + required and how to get updates for these packages. Beware that using + excessively old versions of these packages can cause indirect + errors that are very difficult to track down, so don't assume that + you can just update packages when obvious problems arise during + build or operation. + +Build directory for the kernel +------------------------------ + + When compiling the kernel, all output files will per default be + stored together with the kernel source code. + Using the option ``make O=output/dir`` allows you to specify an alternate + place for the output files (including .config). + Example:: + + kernel source code: /usr/src/linux-4.X + build directory: /home/name/build/kernel + + To configure and build the kernel, use:: + + cd /usr/src/linux-4.X + make O=/home/name/build/kernel menuconfig + make O=/home/name/build/kernel + sudo make O=/home/name/build/kernel modules_install install + + Please note: If the ``O=output/dir`` option is used, then it must be + used for all invocations of make. + +Configuring the kernel +---------------------- + + Do not skip this step even if you are only upgrading one minor + version. New configuration options are added in each release, and + odd problems will turn up if the configuration files are not set up + as expected. If you want to carry your existing configuration to a + new version with minimal work, use ``make oldconfig``, which will + only ask you for the answers to new questions. + + - Alternative configuration commands are:: + + "make config" Plain text interface. + + "make menuconfig" Text based color menus, radiolists & dialogs. + + "make nconfig" Enhanced text based color menus. + + "make xconfig" Qt based configuration tool. + + "make gconfig" GTK+ based configuration tool. + + "make oldconfig" Default all questions based on the contents of + your existing ./.config file and asking about + new config symbols. + + "make silentoldconfig" + Like above, but avoids cluttering the screen + with questions already answered. + Additionally updates the dependencies. + + "make olddefconfig" + Like above, but sets new symbols to their default + values without prompting. + + "make defconfig" Create a ./.config file by using the default + symbol values from either arch/$ARCH/defconfig + or arch/$ARCH/configs/${PLATFORM}_defconfig, + depending on the architecture. + + "make ${PLATFORM}_defconfig" + Create a ./.config file by using the default + symbol values from + arch/$ARCH/configs/${PLATFORM}_defconfig. + Use "make help" to get a list of all available + platforms of your architecture. + + "make allyesconfig" + Create a ./.config file by setting symbol + values to 'y' as much as possible. + + "make allmodconfig" + Create a ./.config file by setting symbol + values to 'm' as much as possible. + + "make allnoconfig" Create a ./.config file by setting symbol + values to 'n' as much as possible. + + "make randconfig" Create a ./.config file by setting symbol + values to random values. + + "make localmodconfig" Create a config based on current config and + loaded modules (lsmod). Disables any module + option that is not needed for the loaded modules. + + To create a localmodconfig for another machine, + store the lsmod of that machine into a file + and pass it in as a LSMOD parameter. + + target$ lsmod > /tmp/mylsmod + target$ scp /tmp/mylsmod host:/tmp + + host$ make LSMOD=/tmp/mylsmod localmodconfig + + The above also works when cross compiling. + + "make localyesconfig" Similar to localmodconfig, except it will convert + all module options to built in (=y) options. + + You can find more information on using the Linux kernel config tools + in Documentation/kbuild/kconfig.txt. + + - NOTES on ``make config``: + + - Having unnecessary drivers will make the kernel bigger, and can + under some circumstances lead to problems: probing for a + nonexistent controller card may confuse your other controllers + + - A kernel with math-emulation compiled in will still use the + coprocessor if one is present: the math emulation will just + never get used in that case. The kernel will be slightly larger, + but will work on different machines regardless of whether they + have a math coprocessor or not. + + - The "kernel hacking" configuration details usually result in a + bigger or slower kernel (or both), and can even make the kernel + less stable by configuring some routines to actively try to + break bad code to find kernel problems (kmalloc()). Thus you + should probably answer 'n' to the questions for "development", + "experimental", or "debugging" features. + +Compiling the kernel +-------------------- + + - Make sure you have at least gcc 3.2 available. + For more information, refer to :ref:`Documentation/process/changes.rst <changes>`. + + Please note that you can still run a.out user programs with this kernel. + + - Do a ``make`` to create a compressed kernel image. It is also + possible to do ``make install`` if you have lilo installed to suit the + kernel makefiles, but you may want to check your particular lilo setup first. + + To do the actual install, you have to be root, but none of the normal + build should require that. Don't take the name of root in vain. + + - If you configured any of the parts of the kernel as ``modules``, you + will also have to do ``make modules_install``. + + - Verbose kernel compile/build output: + + Normally, the kernel build system runs in a fairly quiet mode (but not + totally silent). However, sometimes you or other kernel developers need + to see compile, link, or other commands exactly as they are executed. + For this, use "verbose" build mode. This is done by passing + ``V=1`` to the ``make`` command, e.g.:: + + make V=1 all + + To have the build system also tell the reason for the rebuild of each + target, use ``V=2``. The default is ``V=0``. + + - Keep a backup kernel handy in case something goes wrong. This is + especially true for the development releases, since each new release + contains new code which has not been debugged. Make sure you keep a + backup of the modules corresponding to that kernel, as well. If you + are installing a new kernel with the same version number as your + working kernel, make a backup of your modules directory before you + do a ``make modules_install``. + + Alternatively, before compiling, use the kernel config option + "LOCALVERSION" to append a unique suffix to the regular kernel version. + LOCALVERSION can be set in the "General Setup" menu. + + - In order to boot your new kernel, you'll need to copy the kernel + image (e.g. .../linux/arch/x86/boot/bzImage after compilation) + to the place where your regular bootable kernel is found. + + - Booting a kernel directly from a floppy without the assistance of a + bootloader such as LILO, is no longer supported. + + If you boot Linux from the hard drive, chances are you use LILO, which + uses the kernel image as specified in the file /etc/lilo.conf. The + kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or + /boot/bzImage. To use the new kernel, save a copy of the old image + and copy the new image over the old one. Then, you MUST RERUN LILO + to update the loading map! If you don't, you won't be able to boot + the new kernel image. + + Reinstalling LILO is usually a matter of running /sbin/lilo. + You may wish to edit /etc/lilo.conf to specify an entry for your + old kernel image (say, /vmlinux.old) in case the new one does not + work. See the LILO docs for more information. + + After reinstalling LILO, you should be all set. Shutdown the system, + reboot, and enjoy! + + If you ever need to change the default root device, video mode, + ramdisk size, etc. in the kernel image, use the ``rdev`` program (or + alternatively the LILO boot options when appropriate). No need to + recompile the kernel to change these parameters. + + - Reboot with the new kernel and enjoy. + +If something goes wrong +----------------------- + + - If you have problems that seem to be due to kernel bugs, please check + the file MAINTAINERS to see if there is a particular person associated + with the part of the kernel that you are having trouble with. If there + isn't anyone listed there, then the second best thing is to mail + them to me (torvalds@linux-foundation.org), and possibly to any other + relevant mailing-list or to the newsgroup. + + - In all bug-reports, *please* tell what kernel you are talking about, + how to duplicate the problem, and what your setup is (use your common + sense). If the problem is new, tell me so, and if the problem is + old, please try to tell me when you first noticed it. + + - If the bug results in a message like:: + + unable to handle kernel paging request at address C0000010 + Oops: 0002 + EIP: 0010:XXXXXXXX + eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx + esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx + ds: xxxx es: xxxx fs: xxxx gs: xxxx + Pid: xx, process nr: xx + xx xx xx xx xx xx xx xx xx xx + + or similar kernel debugging information on your screen or in your + system log, please duplicate it *exactly*. The dump may look + incomprehensible to you, but it does contain information that may + help debugging the problem. The text above the dump is also + important: it tells something about why the kernel dumped code (in + the above example, it's due to a bad kernel pointer). More information + on making sense of the dump is in Documentation/admin-guide/oops-tracing.rst + + - If you compiled the kernel with CONFIG_KALLSYMS you can send the dump + as is, otherwise you will have to use the ``ksymoops`` program to make + sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred). + This utility can be downloaded from + ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ . + Alternatively, you can do the dump lookup by hand: + + - In debugging dumps like the above, it helps enormously if you can + look up what the EIP value means. The hex value as such doesn't help + me or anybody else very much: it will depend on your particular + kernel setup. What you should do is take the hex value from the EIP + line (ignore the ``0010:``), and look it up in the kernel namelist to + see which kernel function contains the offending address. + + To find out the kernel function name, you'll need to find the system + binary associated with the kernel that exhibited the symptom. This is + the file 'linux/vmlinux'. To extract the namelist and match it against + the EIP from the kernel crash, do:: + + nm vmlinux | sort | less + + This will give you a list of kernel addresses sorted in ascending + order, from which it is simple to find the function that contains the + offending address. Note that the address given by the kernel + debugging messages will not necessarily match exactly with the + function addresses (in fact, that is very unlikely), so you can't + just 'grep' the list: the list will, however, give you the starting + point of each kernel function, so by looking for the function that + has a starting address lower than the one you are searching for but + is followed by a function with a higher address you will find the one + you want. In fact, it may be a good idea to include a bit of + "context" in your problem report, giving a few lines around the + interesting one. + + If you for some reason cannot do the above (you have a pre-compiled + kernel image or similar), telling me as much about your setup as + possible will help. Please read the :ref:`admin-guide/reporting-bugs.rst <reportingbugs>` + document for details. + + - Alternatively, you can use gdb on a running kernel. (read-only; i.e. you + cannot change values or set break points.) To do this, first compile the + kernel with -g; edit arch/x86/Makefile appropriately, then do a ``make + clean``. You'll also need to enable CONFIG_PROC_FS (via ``make config``). + + After you've rebooted with the new kernel, do ``gdb vmlinux /proc/kcore``. + You can now use all the usual gdb commands. The command to look up the + point where your system crashed is ``l *0xXXXXXXXX``. (Replace the XXXes + with the EIP value.) + + gdb'ing a non-running kernel currently fails because ``gdb`` (wrongly) + disregards the starting offset for which the kernel is compiled. diff --git a/Documentation/admin-guide/binfmt-misc.rst b/Documentation/admin-guide/binfmt-misc.rst new file mode 100644 index 000000000000..97b0d7927078 --- /dev/null +++ b/Documentation/admin-guide/binfmt-misc.rst @@ -0,0 +1,151 @@ +Kernel Support for miscellaneous (your favourite) Binary Formats v1.1 +===================================================================== + +This Kernel feature allows you to invoke almost (for restrictions see below) +every program by simply typing its name in the shell. +This includes for example compiled Java(TM), Python or Emacs programs. + +To achieve this you must tell binfmt_misc which interpreter has to be invoked +with which binary. Binfmt_misc recognises the binary-type by matching some bytes +at the beginning of the file with a magic byte sequence (masking out specified +bits) you have supplied. Binfmt_misc can also recognise a filename extension +aka ``.com`` or ``.exe``. + +First you must mount binfmt_misc:: + + mount binfmt_misc -t binfmt_misc /proc/sys/fs/binfmt_misc + +To actually register a new binary type, you have to set up a string looking like +``:name:type:offset:magic:mask:interpreter:flags`` (where you can choose the +``:`` upon your needs) and echo it to ``/proc/sys/fs/binfmt_misc/register``. + +Here is what the fields mean: + +- ``name`` + is an identifier string. A new /proc file will be created with this + ``name below /proc/sys/fs/binfmt_misc``; cannot contain slashes ``/`` for + obvious reasons. +- ``type`` + is the type of recognition. Give ``M`` for magic and ``E`` for extension. +- ``offset`` + is the offset of the magic/mask in the file, counted in bytes. This + defaults to 0 if you omit it (i.e. you write ``:name:type::magic...``). + Ignored when using filename extension matching. +- ``magic`` + is the byte sequence binfmt_misc is matching for. The magic string + may contain hex-encoded characters like ``\x0a`` or ``\xA4``. Note that you + must escape any NUL bytes; parsing halts at the first one. In a shell + environment you might have to write ``\\x0a`` to prevent the shell from + eating your ``\``. + If you chose filename extension matching, this is the extension to be + recognised (without the ``.``, the ``\x0a`` specials are not allowed). + Extension matching is case sensitive, and slashes ``/`` are not allowed! +- ``mask`` + is an (optional, defaults to all 0xff) mask. You can mask out some + bits from matching by supplying a string like magic and as long as magic. + The mask is anded with the byte sequence of the file. Note that you must + escape any NUL bytes; parsing halts at the first one. Ignored when using + filename extension matching. +- ``interpreter`` + is the program that should be invoked with the binary as first + argument (specify the full path) +- ``flags`` + is an optional field that controls several aspects of the invocation + of the interpreter. It is a string of capital letters, each controls a + certain aspect. The following flags are supported: + + ``P`` - preserve-argv[0] + Legacy behavior of binfmt_misc is to overwrite + the original argv[0] with the full path to the binary. When this + flag is included, binfmt_misc will add an argument to the argument + vector for this purpose, thus preserving the original ``argv[0]``. + e.g. If your interp is set to ``/bin/foo`` and you run ``blah`` + (which is in ``/usr/local/bin``), then the kernel will execute + ``/bin/foo`` with ``argv[]`` set to ``["/bin/foo", "/usr/local/bin/blah", "blah"]``. The interp has to be aware of this so it can + execute ``/usr/local/bin/blah`` + with ``argv[]`` set to ``["blah"]``. + ``O`` - open-binary + Legacy behavior of binfmt_misc is to pass the full path + of the binary to the interpreter as an argument. When this flag is + included, binfmt_misc will open the file for reading and pass its + descriptor as an argument, instead of the full path, thus allowing + the interpreter to execute non-readable binaries. This feature + should be used with care - the interpreter has to be trusted not to + emit the contents of the non-readable binary. + ``C`` - credentials + Currently, the behavior of binfmt_misc is to calculate + the credentials and security token of the new process according to + the interpreter. When this flag is included, these attributes are + calculated according to the binary. It also implies the ``O`` flag. + This feature should be used with care as the interpreter + will run with root permissions when a setuid binary owned by root + is run with binfmt_misc. + ``F`` - fix binary + The usual behaviour of binfmt_misc is to spawn the + binary lazily when the misc format file is invoked. However, + this doesn``t work very well in the face of mount namespaces and + changeroots, so the ``F`` mode opens the binary as soon as the + emulation is installed and uses the opened image to spawn the + emulator, meaning it is always available once installed, + regardless of how the environment changes. + + +There are some restrictions: + + - the whole register string may not exceed 1920 characters + - the magic must reside in the first 128 bytes of the file, i.e. + offset+size(magic) has to be less than 128 + - the interpreter string may not exceed 127 characters + +To use binfmt_misc you have to mount it first. You can mount it with +``mount -t binfmt_misc none /proc/sys/fs/binfmt_misc`` command, or you can add +a line ``none /proc/sys/fs/binfmt_misc binfmt_misc defaults 0 0`` to your +``/etc/fstab`` so it auto mounts on boot. + +You may want to add the binary formats in one of your ``/etc/rc`` scripts during +boot-up. Read the manual of your init program to figure out how to do this +right. + +Think about the order of adding entries! Later added entries are matched first! + + +A few examples (assumed you are in ``/proc/sys/fs/binfmt_misc``): + +- enable support for em86 (like binfmt_em86, for Alpha AXP only):: + + echo ':i386:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x03:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:' > register + echo ':i486:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x06:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:' > register + +- enable support for packed DOS applications (pre-configured dosemu hdimages):: + + echo ':DEXE:M::\x0eDEX::/usr/bin/dosexec:' > register + +- enable support for Windows executables using wine:: + + echo ':DOSWin:M::MZ::/usr/local/bin/wine:' > register + +For java support see Documentation/admin-guide/java.rst + + +You can enable/disable binfmt_misc or one binary type by echoing 0 (to disable) +or 1 (to enable) to ``/proc/sys/fs/binfmt_misc/status`` or +``/proc/.../the_name``. +Catting the file tells you the current status of ``binfmt_misc/the_entry``. + +You can remove one entry or all entries by echoing -1 to ``/proc/.../the_name`` +or ``/proc/sys/fs/binfmt_misc/status``. + + +Hints +----- + +If you want to pass special arguments to your interpreter, you can +write a wrapper script for it. See Documentation/admin-guide/java.rst for an +example. + +Your interpreter should NOT look in the PATH for the filename; the kernel +passes it the full filename (or the file descriptor) to use. Using ``$PATH`` can +cause unexpected behaviour and can be a security hazard. + + +Richard Günther <rguenth@tat.physik.uni-tuebingen.de> diff --git a/Documentation/admin-guide/braille-console.rst b/Documentation/admin-guide/braille-console.rst new file mode 100644 index 000000000000..18e79337dcfd --- /dev/null +++ b/Documentation/admin-guide/braille-console.rst @@ -0,0 +1,38 @@ +Linux Braille Console +===================== + +To get early boot messages on a braille device (before userspace screen +readers can start), you first need to compile the support for the usual serial +console (see :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`), and +for braille device +(in :menuselection:`Device Drivers --> Accessibility support --> Console on braille device`). + +Then you need to specify a ``console=brl``, option on the kernel command line, the +format is:: + + console=brl,serial_options... + +where ``serial_options...`` are the same as described in +:ref:`Documentation/admin-guide/serial-console.rst <serial_console>`. + +So for instance you can use ``console=brl,ttyS0`` if the braille device is connected to the first serial port, and ``console=brl,ttyS0,115200`` to +override the baud rate to 115200, etc. + +By default, the braille device will just show the last kernel message (console +mode). To review previous messages, press the Insert key to switch to the VT +review mode. In review mode, the arrow keys permit to browse in the VT content, +:kbd:`PAGE-UP`/:kbd:`PAGE-DOWN` keys go at the top/bottom of the screen, and +the :kbd:`HOME` key goes back +to the cursor, hence providing very basic screen reviewing facility. + +Sound feedback can be obtained by adding the ``braille_console.sound=1`` kernel +parameter. + +For simplicity, only one braille console can be enabled, other uses of +``console=brl,...`` will be discarded. Also note that it does not interfere with +the console selection mechanism described in +:ref:`Documentation/admin-guide/serial-console.rst <serial_console>`. + +For now, only the VisioBraille device is supported. + +Samuel Thibault <samuel.thibault@ens-lyon.org> diff --git a/Documentation/admin-guide/bug-bisect.rst b/Documentation/admin-guide/bug-bisect.rst new file mode 100644 index 000000000000..59567da344e8 --- /dev/null +++ b/Documentation/admin-guide/bug-bisect.rst @@ -0,0 +1,76 @@ +Bisecting a bug ++++++++++++++++ + +Last updated: 28 October 2016 + +Introduction +============ + +Always try the latest kernel from kernel.org and build from source. If you are +not confident in doing that please report the bug to your distribution vendor +instead of to a kernel developer. + +Finding bugs is not always easy. Have a go though. If you can't find it don't +give up. Report as much as you have found to the relevant maintainer. See +MAINTAINERS for who that is for the subsystem you have worked on. + +Before you submit a bug report read +:ref:`Documentation/admin-guide/reporting-bugs.rst <reportingbugs>`. + +Devices not appearing +===================== + +Often this is caused by udev/systemd. Check that first before blaming it +on the kernel. + +Finding patch that caused a bug +=============================== + +Using the provided tools with ``git`` makes finding bugs easy provided the bug +is reproducible. + +Steps to do it: + +- build the Kernel from its git source +- start bisect with [#f1]_:: + + $ git bisect start + +- mark the broken changeset with:: + + $ git bisect bad [commit] + +- mark a changeset where the code is known to work with:: + + $ git bisect good [commit] + +- rebuild the Kernel and test +- interact with git bisect by using either:: + + $ git bisect good + + or:: + + $ git bisect bad + + depending if the bug happened on the changeset you're testing +- After some interactions, git bisect will give you the changeset that + likely caused the bug. + +- For example, if you know that the current version is bad, and version + 4.8 is good, you could do:: + + $ git bisect start + $ git bisect bad # Current version is bad + $ git bisect good v4.8 + + +.. [#f1] You can, optionally, provide both good and bad arguments at git + start with ``git bisect start [BAD] [GOOD]`` + +For further references, please read: + +- The man page for ``git-bisect`` +- `Fighting regressions with git bisect <https://www.kernel.org/pub/software/scm/git/docs/git-bisect-lk2009.html>`_ +- `Fully automated bisecting with "git bisect run" <https://lwn.net/Articles/317154>`_ +- `Using Git bisect to figure out when brokenness was introduced <http://webchick.net/node/99>`_ diff --git a/Documentation/admin-guide/bug-hunting.rst b/Documentation/admin-guide/bug-hunting.rst new file mode 100644 index 000000000000..08c4b1308189 --- /dev/null +++ b/Documentation/admin-guide/bug-hunting.rst @@ -0,0 +1,369 @@ +Bug hunting +=========== + +Kernel bug reports often come with a stack dump like the one below:: + + ------------[ cut here ]------------ + WARNING: CPU: 1 PID: 28102 at kernel/module.c:1108 module_put+0x57/0x70 + Modules linked in: dvb_usb_gp8psk(-) dvb_usb dvb_core nvidia_drm(PO) nvidia_modeset(PO) snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer snd soundcore nvidia(PO) [last unloaded: rc_core] + CPU: 1 PID: 28102 Comm: rmmod Tainted: P WC O 4.8.4-build.1 #1 + Hardware name: MSI MS-7309/MS-7309, BIOS V1.12 02/23/2009 + 00000000 c12ba080 00000000 00000000 c103ed6a c1616014 00000001 00006dc6 + c1615862 00000454 c109e8a7 c109e8a7 00000009 ffffffff 00000000 f13f6a10 + f5f5a600 c103ee33 00000009 00000000 00000000 c109e8a7 f80ca4d0 c109f617 + Call Trace: + [<c12ba080>] ? dump_stack+0x44/0x64 + [<c103ed6a>] ? __warn+0xfa/0x120 + [<c109e8a7>] ? module_put+0x57/0x70 + [<c109e8a7>] ? module_put+0x57/0x70 + [<c103ee33>] ? warn_slowpath_null+0x23/0x30 + [<c109e8a7>] ? module_put+0x57/0x70 + [<f80ca4d0>] ? gp8psk_fe_set_frontend+0x460/0x460 [dvb_usb_gp8psk] + [<c109f617>] ? symbol_put_addr+0x27/0x50 + [<f80bc9ca>] ? dvb_usb_adapter_frontend_exit+0x3a/0x70 [dvb_usb] + [<f80bb3bf>] ? dvb_usb_exit+0x2f/0xd0 [dvb_usb] + [<c13d03bc>] ? usb_disable_endpoint+0x7c/0xb0 + [<f80bb48a>] ? dvb_usb_device_exit+0x2a/0x50 [dvb_usb] + [<c13d2882>] ? usb_unbind_interface+0x62/0x250 + [<c136b514>] ? __pm_runtime_idle+0x44/0x70 + [<c13620d8>] ? __device_release_driver+0x78/0x120 + [<c1362907>] ? driver_detach+0x87/0x90 + [<c1361c48>] ? bus_remove_driver+0x38/0x90 + [<c13d1c18>] ? usb_deregister+0x58/0xb0 + [<c109fbb0>] ? SyS_delete_module+0x130/0x1f0 + [<c1055654>] ? task_work_run+0x64/0x80 + [<c1000fa5>] ? exit_to_usermode_loop+0x85/0x90 + [<c10013f0>] ? do_fast_syscall_32+0x80/0x130 + [<c1549f43>] ? sysenter_past_esp+0x40/0x6a + ---[ end trace 6ebc60ef3981792f ]--- + +Such stack traces provide enough information to identify the line inside the +Kernel's source code where the bug happened. Depending on the severity of +the issue, it may also contain the word **Oops**, as on this one:: + + BUG: unable to handle kernel NULL pointer dereference at (null) + IP: [<c06969d4>] iret_exc+0x7d0/0xa59 + *pdpt = 000000002258a001 *pde = 0000000000000000 + Oops: 0002 [#1] PREEMPT SMP + ... + +Despite being an **Oops** or some other sort of stack trace, the offended +line is usually required to identify and handle the bug. Along this chapter, +we'll refer to "Oops" for all kinds of stack traces that need to be analized. + +.. note:: + + ``ksymoops`` is useless on 2.6 or upper. Please use the Oops in its original + format (from ``dmesg``, etc). Ignore any references in this or other docs to + "decoding the Oops" or "running it through ksymoops". + If you post an Oops from 2.6+ that has been run through ``ksymoops``, + people will just tell you to repost it. + +Where is the Oops message is located? +------------------------------------- + +Normally the Oops text is read from the kernel buffers by klogd and +handed to ``syslogd`` which writes it to a syslog file, typically +``/var/log/messages`` (depends on ``/etc/syslog.conf``). On systems with +systemd, it may also be stored by the ``journald`` daemon, and accessed +by running ``journalctl`` command. + +Sometimes ``klogd`` dies, in which case you can run ``dmesg > file`` to +read the data from the kernel buffers and save it. Or you can +``cat /proc/kmsg > file``, however you have to break in to stop the transfer, +``kmsg`` is a "never ending file". + +If the machine has crashed so badly that you cannot enter commands or +the disk is not available then you have three options: + +(1) Hand copy the text from the screen and type it in after the machine + has restarted. Messy but it is the only option if you have not + planned for a crash. Alternatively, you can take a picture of + the screen with a digital camera - not nice, but better than + nothing. If the messages scroll off the top of the console, you + may find that booting with a higher resolution (eg, ``vga=791``) + will allow you to read more of the text. (Caveat: This needs ``vesafb``, + so won't help for 'early' oopses) + +(2) Boot with a serial console (see + :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`), + run a null modem to a second machine and capture the output there + using your favourite communication program. Minicom works well. + +(3) Use Kdump (see Documentation/kdump/kdump.txt), + extract the kernel ring buffer from old memory with using dmesg + gdbmacro in Documentation/kdump/gdbmacros.txt. + +Finding the bug's location +-------------------------- + +Reporting a bug works best if you point the location of the bug at the +Kernel source file. There are two methods for doing that. Usually, using +``gdb`` is easier, but the Kernel should be pre-compiled with debug info. + +gdb +^^^ + +The GNU debug (``gdb``) is the best way to figure out the exact file and line +number of the OOPS from the ``vmlinux`` file. + +The usage of gdb works best on a kernel compiled with ``CONFIG_DEBUG_INFO``. +This can be set by running:: + + $ ./scripts/config -d COMPILE_TEST -e DEBUG_KERNEL -e DEBUG_INFO + +On a kernel compiled with ``CONFIG_DEBUG_INFO``, you can simply copy the +EIP value from the OOPS:: + + EIP: 0060:[<c021e50e>] Not tainted VLI + +And use GDB to translate that to human-readable form:: + + $ gdb vmlinux + (gdb) l *0xc021e50e + +If you don't have ``CONFIG_DEBUG_INFO`` enabled, you use the function +offset from the OOPS:: + + EIP is at vt_ioctl+0xda8/0x1482 + +And recompile the kernel with ``CONFIG_DEBUG_INFO`` enabled:: + + $ ./scripts/config -d COMPILE_TEST -e DEBUG_KERNEL -e DEBUG_INFO + $ make vmlinux + $ gdb vmlinux + (gdb) l *vt_ioctl+0xda8 + 0x1888 is in vt_ioctl (drivers/tty/vt/vt_ioctl.c:293). + 288 { + 289 struct vc_data *vc = NULL; + 290 int ret = 0; + 291 + 292 console_lock(); + 293 if (VT_BUSY(vc_num)) + 294 ret = -EBUSY; + 295 else if (vc_num) + 296 vc = vc_deallocate(vc_num); + 297 console_unlock(); + +or, if you want to be more verbose:: + + (gdb) p vt_ioctl + $1 = {int (struct tty_struct *, unsigned int, unsigned long)} 0xae0 <vt_ioctl> + (gdb) l *0xae0+0xda8 + +You could, instead, use the object file:: + + $ make drivers/tty/ + $ gdb drivers/tty/vt/vt_ioctl.o + (gdb) l *vt_ioctl+0xda8 + +If you have a call trace, such as:: + + Call Trace: + [<ffffffff8802c8e9>] :jbd:log_wait_commit+0xa3/0xf5 + [<ffffffff810482d9>] autoremove_wake_function+0x0/0x2e + [<ffffffff8802770b>] :jbd:journal_stop+0x1be/0x1ee + ... + +this shows the problem likely in the :jbd: module. You can load that module +in gdb and list the relevant code:: + + $ gdb fs/jbd/jbd.ko + (gdb) l *log_wait_commit+0xa3 + +.. note:: + + You can also do the same for any function call at the stack trace, + like this one:: + + [<f80bc9ca>] ? dvb_usb_adapter_frontend_exit+0x3a/0x70 [dvb_usb] + + The position where the above call happened can be seen with:: + + $ gdb drivers/media/usb/dvb-usb/dvb-usb.o + (gdb) l *dvb_usb_adapter_frontend_exit+0x3a + +objdump +^^^^^^^ + +To debug a kernel, use objdump and look for the hex offset from the crash +output to find the valid line of code/assembler. Without debug symbols, you +will see the assembler code for the routine shown, but if your kernel has +debug symbols the C code will also be available. (Debug symbols can be enabled +in the kernel hacking menu of the menu configuration.) For example:: + + $ objdump -r -S -l --disassemble net/dccp/ipv4.o + +.. note:: + + You need to be at the top level of the kernel tree for this to pick up + your C files. + +If you don't have access to the code you can also debug on some crash dumps +e.g. crash dump output as shown by Dave Miller:: + + EIP is at +0x14/0x4c0 + ... + Code: 44 24 04 e8 6f 05 00 00 e9 e8 fe ff ff 8d 76 00 8d bc 27 00 00 + 00 00 55 57 56 53 81 ec bc 00 00 00 8b ac 24 d0 00 00 00 8b 5d 08 + <8b> 83 3c 01 00 00 89 44 24 14 8b 45 28 85 c0 89 44 24 18 0f 85 + + Put the bytes into a "foo.s" file like this: + + .text + .globl foo + foo: + .byte .... /* bytes from Code: part of OOPS dump */ + + Compile it with "gcc -c -o foo.o foo.s" then look at the output of + "objdump --disassemble foo.o". + + Output: + + ip_queue_xmit: + push %ebp + push %edi + push %esi + push %ebx + sub $0xbc, %esp + mov 0xd0(%esp), %ebp ! %ebp = arg0 (skb) + mov 0x8(%ebp), %ebx ! %ebx = skb->sk + mov 0x13c(%ebx), %eax ! %eax = inet_sk(sk)->opt + +Reporting the bug +----------------- + +Once you find where the bug happened, by inspecting its location, +you could either try to fix it yourself or report it upstream. + +In order to report it upstream, you should identify the mailing list +used for the development of the affected code. This can be done by using +the ``get_maintainer.pl`` script. + +For example, if you find a bug at the gspca's conex.c file, you can get +their maintainers with:: + + $ ./scripts/get_maintainer.pl -f drivers/media/usb/gspca/sonixj.c + Hans Verkuil <hverkuil@xs4all.nl> (odd fixer:GSPCA USB WEBCAM DRIVER,commit_signer:1/1=100%) + Mauro Carvalho Chehab <mchehab@kernel.org> (maintainer:MEDIA INPUT INFRASTRUCTURE (V4L/DVB),commit_signer:1/1=100%) + Tejun Heo <tj@kernel.org> (commit_signer:1/1=100%) + Bhaktipriya Shridhar <bhaktipriya96@gmail.com> (commit_signer:1/1=100%,authored:1/1=100%,added_lines:4/4=100%,removed_lines:9/9=100%) + linux-media@vger.kernel.org (open list:GSPCA USB WEBCAM DRIVER) + linux-kernel@vger.kernel.org (open list) + +Please notice that it will point to: + +- The last developers that touched on the source code. On the above example, + Tejun and Bhaktipriya (in this specific case, none really envolved on the + development of this file); +- The driver maintainer (Hans Verkuil); +- The subsystem maintainer (Mauro Carvalho Chehab) +- The driver and/or subsystem mailing list (linux-media@vger.kernel.org); +- the Linux Kernel mailing list (linux-kernel@vger.kernel.org). + +Usually, the fastest way to have your bug fixed is to report it to mailing +list used for the development of the code (linux-media ML) copying the driver maintainer (Hans). + +If you are totally stumped as to whom to send the report, and +``get_maintainer.pl`` didn't provide you anything useful, send it to +linux-kernel@vger.kernel.org. + +Thanks for your help in making Linux as stable as humanly possible. + +Fixing the bug +-------------- + +If you know programming, you could help us by not only reporting the bug, +but also providing us with a solution. After all open source is about +sharing what you do and don't you want to be recognised for your genius? + +If you decide to take this way, once you have worked out a fix please submit +it upstream. + +Please do read +ref:`Documentation/process/submitting-patches.rst <submittingpatches>` though +to help your code get accepted. + + +--------------------------------------------------------------------------- + +Notes on Oops tracing with ``klogd`` +------------------------------------ + +In order to help Linus and the other kernel developers there has been +substantial support incorporated into ``klogd`` for processing protection +faults. In order to have full support for address resolution at least +version 1.3-pl3 of the ``sysklogd`` package should be used. + +When a protection fault occurs the ``klogd`` daemon automatically +translates important addresses in the kernel log messages to their +symbolic equivalents. This translated kernel message is then +forwarded through whatever reporting mechanism ``klogd`` is using. The +protection fault message can be simply cut out of the message files +and forwarded to the kernel developers. + +Two types of address resolution are performed by ``klogd``. The first is +static translation and the second is dynamic translation. Static +translation uses the System.map file in much the same manner that +ksymoops does. In order to do static translation the ``klogd`` daemon +must be able to find a system map file at daemon initialization time. +See the klogd man page for information on how ``klogd`` searches for map +files. + +Dynamic address translation is important when kernel loadable modules +are being used. Since memory for kernel modules is allocated from the +kernel's dynamic memory pools there are no fixed locations for either +the start of the module or for functions and symbols in the module. + +The kernel supports system calls which allow a program to determine +which modules are loaded and their location in memory. Using these +system calls the klogd daemon builds a symbol table which can be used +to debug a protection fault which occurs in a loadable kernel module. + +At the very minimum klogd will provide the name of the module which +generated the protection fault. There may be additional symbolic +information available if the developer of the loadable module chose to +export symbol information from the module. + +Since the kernel module environment can be dynamic there must be a +mechanism for notifying the ``klogd`` daemon when a change in module +environment occurs. There are command line options available which +allow klogd to signal the currently executing daemon that symbol +information should be refreshed. See the ``klogd`` manual page for more +information. + +A patch is included with the sysklogd distribution which modifies the +``modules-2.0.0`` package to automatically signal klogd whenever a module +is loaded or unloaded. Applying this patch provides essentially +seamless support for debugging protection faults which occur with +kernel loadable modules. + +The following is an example of a protection fault in a loadable module +processed by ``klogd``:: + + Aug 29 09:51:01 blizard kernel: Unable to handle kernel paging request at virtual address f15e97cc + Aug 29 09:51:01 blizard kernel: current->tss.cr3 = 0062d000, %cr3 = 0062d000 + Aug 29 09:51:01 blizard kernel: *pde = 00000000 + Aug 29 09:51:01 blizard kernel: Oops: 0002 + Aug 29 09:51:01 blizard kernel: CPU: 0 + Aug 29 09:51:01 blizard kernel: EIP: 0010:[oops:_oops+16/3868] + Aug 29 09:51:01 blizard kernel: EFLAGS: 00010212 + Aug 29 09:51:01 blizard kernel: eax: 315e97cc ebx: 003a6f80 ecx: 001be77b edx: 00237c0c + Aug 29 09:51:01 blizard kernel: esi: 00000000 edi: bffffdb3 ebp: 00589f90 esp: 00589f8c + Aug 29 09:51:01 blizard kernel: ds: 0018 es: 0018 fs: 002b gs: 002b ss: 0018 + Aug 29 09:51:01 blizard kernel: Process oops_test (pid: 3374, process nr: 21, stackpage=00589000) + Aug 29 09:51:01 blizard kernel: Stack: 315e97cc 00589f98 0100b0b4 bffffed4 0012e38e 00240c64 003a6f80 00000001 + Aug 29 09:51:01 blizard kernel: 00000000 00237810 bfffff00 0010a7fa 00000003 00000001 00000000 bfffff00 + Aug 29 09:51:01 blizard kernel: bffffdb3 bffffed4 ffffffda 0000002b 0007002b 0000002b 0000002b 00000036 + Aug 29 09:51:01 blizard kernel: Call Trace: [oops:_oops_ioctl+48/80] [_sys_ioctl+254/272] [_system_call+82/128] + Aug 29 09:51:01 blizard kernel: Code: c7 00 05 00 00 00 eb 08 90 90 90 90 90 90 90 90 89 ec 5d c3 + +--------------------------------------------------------------------------- + +:: + + Dr. G.W. Wettstein Oncology Research Div. Computing Facility + Roger Maris Cancer Center INTERNET: greg@wind.rmcc.com + 820 4th St. N. + Fargo, ND 58122 + Phone: 701-234-7556 diff --git a/Documentation/admin-guide/conf.py b/Documentation/admin-guide/conf.py new file mode 100644 index 000000000000..86f738953799 --- /dev/null +++ b/Documentation/admin-guide/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = 'Linux Kernel User Documentation' + +tags.add("subproject") + +latex_documents = [ + ('index', 'linux-user.tex', 'Linux Kernel User Documentation', + 'The kernel development community', 'manual'), +] diff --git a/Documentation/admin-guide/devices.rst b/Documentation/admin-guide/devices.rst new file mode 100644 index 000000000000..7fadc05330dd --- /dev/null +++ b/Documentation/admin-guide/devices.rst @@ -0,0 +1,268 @@ + +Linux allocated devices (4.x+ version) +====================================== + +This list is the Linux Device List, the official registry of allocated +device numbers and ``/dev`` directory nodes for the Linux operating +system. + +The LaTeX version of this document is no longer maintained, nor is +the document that used to reside at lanana.org. This version in the +mainline Linux kernel is the master document. Updates shall be sent +as patches to the kernel maintainers (see the +:ref:`Documentation/process/submitting-patches.rst <submittingpatches>` document). +Specifically explore the sections titled "CHAR and MISC DRIVERS", and +"BLOCK LAYER" in the MAINTAINERS file to find the right maintainers +to involve for character and block devices. + +This document is included by reference into the Filesystem Hierarchy +Standard (FHS). The FHS is available from http://www.pathname.com/fhs/. + +Allocations marked (68k/Amiga) apply to Linux/68k on the Amiga +platform only. Allocations marked (68k/Atari) apply to Linux/68k on +the Atari platform only. + +This document is in the public domain. The authors requests, however, +that semantically altered versions are not distributed without +permission of the authors, assuming the authors can be contacted without +an unreasonable effort. + + +.. attention:: + + DEVICE DRIVERS AUTHORS PLEASE READ THIS + + Linux now has extensive support for dynamic allocation of device numbering + and can use ``sysfs`` and ``udev`` (``systemd``) to handle the naming needs. + There are still some exceptions in the serial and boot device area. Before + asking for a device number make sure you actually need one. + + To have a major number allocated, or a minor number in situations + where that applies (e.g. busmice), please submit a patch and send to + the authors as indicated above. + + Keep the description of the device *in the same format + as this list*. The reason for this is that it is the only way we have + found to ensure we have all the requisite information to publish your + device and avoid conflicts. + + Finally, sometimes we have to play "namespace police." Please don't be + offended. We often get submissions for ``/dev`` names that would be bound + to cause conflicts down the road. We are trying to avoid getting in a + situation where we would have to suffer an incompatible forward + change. Therefore, please consult with us **before** you make your + device names and numbers in any way public, at least to the point + where it would be at all difficult to get them changed. + + Your cooperation is appreciated. + +.. include:: devices.txt + :literal: + +Additional ``/dev/`` directory entries +-------------------------------------- + +This section details additional entries that should or may exist in +the /dev directory. It is preferred that symbolic links use the same +form (absolute or relative) as is indicated here. Links are +classified as "hard" or "symbolic" depending on the preferred type of +link; if possible, the indicated type of link should be used. + +Compulsory links +++++++++++++++++ + +These links should exist on all systems: + +=============== =============== =============== =============================== +/dev/fd /proc/self/fd symbolic File descriptors +/dev/stdin fd/0 symbolic stdin file descriptor +/dev/stdout fd/1 symbolic stdout file descriptor +/dev/stderr fd/2 symbolic stderr file descriptor +/dev/nfsd socksys symbolic Required by iBCS-2 +/dev/X0R null symbolic Required by iBCS-2 +=============== =============== =============== =============================== + +Note: ``/dev/X0R`` is <letter X>-<digit 0>-<letter R>. + +Recommended links ++++++++++++++++++ + +It is recommended that these links exist on all systems: + + +=============== =============== =============== =============================== +/dev/core /proc/kcore symbolic Backward compatibility +/dev/ramdisk ram0 symbolic Backward compatibility +/dev/ftape qft0 symbolic Backward compatibility +/dev/bttv0 video0 symbolic Backward compatibility +/dev/radio radio0 symbolic Backward compatibility +/dev/i2o* /dev/i2o/* symbolic Backward compatibility +/dev/scd? sr? hard Alternate SCSI CD-ROM name +=============== =============== =============== =============================== + +Locally defined links ++++++++++++++++++++++ + +The following links may be established locally to conform to the +configuration of the system. This is merely a tabulation of existing +practice, and does not constitute a recommendation. However, if they +exist, they should have the following uses. + +=============== =============== =============== =============================== +/dev/mouse mouse port symbolic Current mouse device +/dev/tape tape device symbolic Current tape device +/dev/cdrom CD-ROM device symbolic Current CD-ROM device +/dev/cdwriter CD-writer symbolic Current CD-writer device +/dev/scanner scanner symbolic Current scanner device +/dev/modem modem port symbolic Current dialout device +/dev/root root device symbolic Current root filesystem +/dev/swap swap device symbolic Current swap device +=============== =============== =============== =============================== + +``/dev/modem`` should not be used for a modem which supports dialin as +well as dialout, as it tends to cause lock file problems. If it +exists, ``/dev/modem`` should point to the appropriate primary TTY device +(the use of the alternate callout devices is deprecated). + +For SCSI devices, ``/dev/tape`` and ``/dev/cdrom`` should point to the +*cooked* devices (``/dev/st*`` and ``/dev/sr*``, respectively), whereas +``/dev/cdwriter`` and /dev/scanner should point to the appropriate generic +SCSI devices (/dev/sg*). + +``/dev/mouse`` may point to a primary serial TTY device, a hardware mouse +device, or a socket for a mouse driver program (e.g. ``/dev/gpmdata``). + +Sockets and pipes ++++++++++++++++++ + +Non-transient sockets and named pipes may exist in /dev. Common entries are: + +=============== =============== =============================================== +/dev/printer socket lpd local socket +/dev/log socket syslog local socket +/dev/gpmdata socket gpm mouse multiplexer +=============== =============== =============================================== + +Mount points +++++++++++++ + +The following names are reserved for mounting special filesystems +under /dev. These special filesystems provide kernel interfaces that +cannot be provided with standard device nodes. + +=============== =============== =============================================== +/dev/pts devpts PTY slave filesystem +/dev/shm tmpfs POSIX shared memory maintenance access +=============== =============== =============================================== + +Terminal devices +---------------- + +Terminal, or TTY devices are a special class of character devices. A +terminal device is any device that could act as a controlling terminal +for a session; this includes virtual consoles, serial ports, and +pseudoterminals (PTYs). + +All terminal devices share a common set of capabilities known as line +disciplines; these include the common terminal line discipline as well +as SLIP and PPP modes. + +All terminal devices are named similarly; this section explains the +naming and use of the various types of TTYs. Note that the naming +conventions include several historical warts; some of these are +Linux-specific, some were inherited from other systems, and some +reflect Linux outgrowing a borrowed convention. + +A hash mark (``#``) in a device name is used here to indicate a decimal +number without leading zeroes. + +Virtual consoles and the console device ++++++++++++++++++++++++++++++++++++++++ + +Virtual consoles are full-screen terminal displays on the system video +monitor. Virtual consoles are named ``/dev/tty#``, with numbering +starting at ``/dev/tty1``; ``/dev/tty0`` is the current virtual console. +``/dev/tty0`` is the device that should be used to access the system video +card on those architectures for which the frame buffer devices +(``/dev/fb*``) are not applicable. Do not use ``/dev/console`` +for this purpose. + +The console device, ``/dev/console``, is the device to which system +messages should be sent, and on which logins should be permitted in +single-user mode. Starting with Linux 2.1.71, ``/dev/console`` is managed +by the kernel; for previous versions it should be a symbolic link to +either ``/dev/tty0``, a specific virtual console such as ``/dev/tty1``, or to +a serial port primary (``tty*``, not ``cu*``) device, depending on the +configuration of the system. + +Serial ports +++++++++++++ + +Serial ports are RS-232 serial ports and any device which simulates +one, either in hardware (such as internal modems) or in software (such +as the ISDN driver.) Under Linux, each serial ports has two device +names, the primary or callin device and the alternate or callout one. +Each kind of device is indicated by a different letter. For any +letter X, the names of the devices are ``/dev/ttyX#`` and ``/dev/cux#``, +respectively; for historical reasons, ``/dev/ttyS#`` and ``/dev/ttyC#`` +correspond to ``/dev/cua#`` and ``/dev/cub#``. In the future, it should be +expected that multiple letters will be used; all letters will be upper +case for the "tty" device (e.g. ``/dev/ttyDP#``) and lower case for the +"cu" device (e.g. ``/dev/cudp#``). + +The names ``/dev/ttyQ#`` and ``/dev/cuq#`` are reserved for local use. + +The alternate devices provide for kernel-based exclusion and somewhat +different defaults than the primary devices. Their main purpose is to +allow the use of serial ports with programs with no inherent or broken +support for serial ports. Their use is deprecated, and they may be +removed from a future version of Linux. + +Arbitration of serial ports is provided by the use of lock files with +the names ``/var/lock/LCK..ttyX#``. The contents of the lock file should +be the PID of the locking process as an ASCII number. + +It is common practice to install links such as /dev/modem +which point to serial ports. In order to ensure proper locking in the +presence of these links, it is recommended that software chase +symlinks and lock all possible names; additionally, it is recommended +that a lock file be installed with the corresponding alternate +device. In order to avoid deadlocks, it is recommended that the locks +are acquired in the following order, and released in the reverse: + + 1. The symbolic link name, if any (``/var/lock/LCK..modem``) + 2. The "tty" name (``/var/lock/LCK..ttyS2``) + 3. The alternate device name (``/var/lock/LCK..cua2``) + +In the case of nested symbolic links, the lock files should be +installed in the order the symlinks are resolved. + +Under no circumstances should an application hold a lock while waiting +for another to be released. In addition, applications which attempt +to create lock files for the corresponding alternate device names +should take into account the possibility of being used on a non-serial +port TTY, for which no alternate device would exist. + +Pseudoterminals (PTYs) +++++++++++++++++++++++ + +Pseudoterminals, or PTYs, are used to create login sessions or provide +other capabilities requiring a TTY line discipline (including SLIP or +PPP capability) to arbitrary data-generation processes. Each PTY has +a master side, named ``/dev/pty[p-za-e][0-9a-f]``, and a slave side, named +``/dev/tty[p-za-e][0-9a-f]``. The kernel arbitrates the use of PTYs by +allowing each master side to be opened only once. + +Once the master side has been opened, the corresponding slave device +can be used in the same manner as any TTY device. The master and +slave devices are connected by the kernel, generating the equivalent +of a bidirectional pipe with TTY capabilities. + +Recent versions of the Linux kernels and GNU libc contain support for +the System V/Unix98 naming scheme for PTYs, which assigns a common +device, ``/dev/ptmx``, to all the masters (opening it will automatically +give you a previously unassigned PTY) and a subdirectory, ``/dev/pts``, +for the slaves; the slaves are named with decimal integers (``/dev/pts/#`` +in our notation). This removes the problem of exhausting the +namespace and enables the kernel to automatically create the device +nodes for the slaves on demand using the "devpts" filesystem. diff --git a/Documentation/admin-guide/devices.txt b/Documentation/admin-guide/devices.txt new file mode 100644 index 000000000000..c9cea2e39c21 --- /dev/null +++ b/Documentation/admin-guide/devices.txt @@ -0,0 +1,3081 @@ + 0 Unnamed devices (e.g. non-device mounts) + 0 = reserved as null device number + See block major 144, 145, 146 for expansion areas. + + 1 char Memory devices + 1 = /dev/mem Physical memory access + 2 = /dev/kmem Kernel virtual memory access + 3 = /dev/null Null device + 4 = /dev/port I/O port access + 5 = /dev/zero Null byte source + 6 = /dev/core OBSOLETE - replaced by /proc/kcore + 7 = /dev/full Returns ENOSPC on write + 8 = /dev/random Nondeterministic random number gen. + 9 = /dev/urandom Faster, less secure random number gen. + 10 = /dev/aio Asynchronous I/O notification interface + 11 = /dev/kmsg Writes to this come out as printk's, reads + export the buffered printk records. + 12 = /dev/oldmem OBSOLETE - replaced by /proc/vmcore + + 1 block RAM disk + 0 = /dev/ram0 First RAM disk + 1 = /dev/ram1 Second RAM disk + ... + 250 = /dev/initrd Initial RAM disk + + Older kernels had /dev/ramdisk (1, 1) here. + /dev/initrd refers to a RAM disk which was preloaded + by the boot loader; newer kernels use /dev/ram0 for + the initrd. + + 2 char Pseudo-TTY masters + 0 = /dev/ptyp0 First PTY master + 1 = /dev/ptyp1 Second PTY master + ... + 255 = /dev/ptyef 256th PTY master + + Pseudo-tty's are named as follows: + * Masters are "pty", slaves are "tty"; + * the fourth letter is one of pqrstuvwxyzabcde indicating + the 1st through 16th series of 16 pseudo-ttys each, and + * the fifth letter is one of 0123456789abcdef indicating + the position within the series. + + These are the old-style (BSD) PTY devices; Unix98 + devices are on major 128 and above and use the PTY + master multiplex (/dev/ptmx) to acquire a PTY on + demand. + + 2 block Floppy disks + 0 = /dev/fd0 Controller 0, drive 0, autodetect + 1 = /dev/fd1 Controller 0, drive 1, autodetect + 2 = /dev/fd2 Controller 0, drive 2, autodetect + 3 = /dev/fd3 Controller 0, drive 3, autodetect + 128 = /dev/fd4 Controller 1, drive 0, autodetect + 129 = /dev/fd5 Controller 1, drive 1, autodetect + 130 = /dev/fd6 Controller 1, drive 2, autodetect + 131 = /dev/fd7 Controller 1, drive 3, autodetect + + To specify format, add to the autodetect device number: + 0 = /dev/fd? Autodetect format + 4 = /dev/fd?d360 5.25" 360K in a 360K drive(1) + 20 = /dev/fd?h360 5.25" 360K in a 1200K drive(1) + 48 = /dev/fd?h410 5.25" 410K in a 1200K drive + 64 = /dev/fd?h420 5.25" 420K in a 1200K drive + 24 = /dev/fd?h720 5.25" 720K in a 1200K drive + 80 = /dev/fd?h880 5.25" 880K in a 1200K drive(1) + 8 = /dev/fd?h1200 5.25" 1200K in a 1200K drive(1) + 40 = /dev/fd?h1440 5.25" 1440K in a 1200K drive(1) + 56 = /dev/fd?h1476 5.25" 1476K in a 1200K drive + 72 = /dev/fd?h1494 5.25" 1494K in a 1200K drive + 92 = /dev/fd?h1600 5.25" 1600K in a 1200K drive(1) + + 12 = /dev/fd?u360 3.5" 360K Double Density(2) + 16 = /dev/fd?u720 3.5" 720K Double Density(1) + 120 = /dev/fd?u800 3.5" 800K Double Density(2) + 52 = /dev/fd?u820 3.5" 820K Double Density + 68 = /dev/fd?u830 3.5" 830K Double Density + 84 = /dev/fd?u1040 3.5" 1040K Double Density(1) + 88 = /dev/fd?u1120 3.5" 1120K Double Density(1) + 28 = /dev/fd?u1440 3.5" 1440K High Density(1) + 124 = /dev/fd?u1600 3.5" 1600K High Density(1) + 44 = /dev/fd?u1680 3.5" 1680K High Density(3) + 60 = /dev/fd?u1722 3.5" 1722K High Density + 76 = /dev/fd?u1743 3.5" 1743K High Density + 96 = /dev/fd?u1760 3.5" 1760K High Density + 116 = /dev/fd?u1840 3.5" 1840K High Density(3) + 100 = /dev/fd?u1920 3.5" 1920K High Density(1) + 32 = /dev/fd?u2880 3.5" 2880K Extra Density(1) + 104 = /dev/fd?u3200 3.5" 3200K Extra Density + 108 = /dev/fd?u3520 3.5" 3520K Extra Density + 112 = /dev/fd?u3840 3.5" 3840K Extra Density(1) + + 36 = /dev/fd?CompaQ Compaq 2880K drive; obsolete? + + (1) Autodetectable format + (2) Autodetectable format in a Double Density (720K) drive only + (3) Autodetectable format in a High Density (1440K) drive only + + NOTE: The letter in the device name (d, q, h or u) + signifies the type of drive: 5.25" Double Density (d), + 5.25" Quad Density (q), 5.25" High Density (h) or 3.5" + (any model, u). The use of the capital letters D, H + and E for the 3.5" models have been deprecated, since + the drive type is insignificant for these devices. + + 3 char Pseudo-TTY slaves + 0 = /dev/ttyp0 First PTY slave + 1 = /dev/ttyp1 Second PTY slave + ... + 255 = /dev/ttyef 256th PTY slave + + These are the old-style (BSD) PTY devices; Unix98 + devices are on major 136 and above. + + 3 block First MFM, RLL and IDE hard disk/CD-ROM interface + 0 = /dev/hda Master: whole disk (or CD-ROM) + 64 = /dev/hdb Slave: whole disk (or CD-ROM) + + For partitions, add to the whole disk device number: + 0 = /dev/hd? Whole disk + 1 = /dev/hd?1 First partition + 2 = /dev/hd?2 Second partition + ... + 63 = /dev/hd?63 63rd partition + + For Linux/i386, partitions 1-4 are the primary + partitions, and 5 and above are logical partitions. + Other versions of Linux use partitioning schemes + appropriate to their respective architectures. + + 4 char TTY devices + 0 = /dev/tty0 Current virtual console + + 1 = /dev/tty1 First virtual console + ... + 63 = /dev/tty63 63rd virtual console + 64 = /dev/ttyS0 First UART serial port + ... + 255 = /dev/ttyS191 192nd UART serial port + + UART serial ports refer to 8250/16450/16550 series devices. + + Older versions of the Linux kernel used this major + number for BSD PTY devices. As of Linux 2.1.115, this + is no longer supported. Use major numbers 2 and 3. + + 4 block Aliases for dynamically allocated major devices to be used + when its not possible to create the real device nodes + because the root filesystem is mounted read-only. + + 0 = /dev/root + + 5 char Alternate TTY devices + 0 = /dev/tty Current TTY device + 1 = /dev/console System console + 2 = /dev/ptmx PTY master multiplex + 3 = /dev/ttyprintk User messages via printk TTY device + 64 = /dev/cua0 Callout device for ttyS0 + ... + 255 = /dev/cua191 Callout device for ttyS191 + + (5,1) is /dev/console starting with Linux 2.1.71. See + the section on terminal devices for more information + on /dev/console. + + 6 char Parallel printer devices + 0 = /dev/lp0 Parallel printer on parport0 + 1 = /dev/lp1 Parallel printer on parport1 + ... + + Current Linux kernels no longer have a fixed mapping + between parallel ports and I/O addresses. Instead, + they are redirected through the parport multiplex layer. + + 7 char Virtual console capture devices + 0 = /dev/vcs Current vc text contents + 1 = /dev/vcs1 tty1 text contents + ... + 63 = /dev/vcs63 tty63 text contents + 128 = /dev/vcsa Current vc text/attribute contents + 129 = /dev/vcsa1 tty1 text/attribute contents + ... + 191 = /dev/vcsa63 tty63 text/attribute contents + + NOTE: These devices permit both read and write access. + + 7 block Loopback devices + 0 = /dev/loop0 First loop device + 1 = /dev/loop1 Second loop device + ... + + The loop devices are used to mount filesystems not + associated with block devices. The binding to the + loop devices is handled by mount(8) or losetup(8). + + 8 block SCSI disk devices (0-15) + 0 = /dev/sda First SCSI disk whole disk + 16 = /dev/sdb Second SCSI disk whole disk + 32 = /dev/sdc Third SCSI disk whole disk + ... + 240 = /dev/sdp Sixteenth SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 9 char SCSI tape devices + 0 = /dev/st0 First SCSI tape, mode 0 + 1 = /dev/st1 Second SCSI tape, mode 0 + ... + 32 = /dev/st0l First SCSI tape, mode 1 + 33 = /dev/st1l Second SCSI tape, mode 1 + ... + 64 = /dev/st0m First SCSI tape, mode 2 + 65 = /dev/st1m Second SCSI tape, mode 2 + ... + 96 = /dev/st0a First SCSI tape, mode 3 + 97 = /dev/st1a Second SCSI tape, mode 3 + ... + 128 = /dev/nst0 First SCSI tape, mode 0, no rewind + 129 = /dev/nst1 Second SCSI tape, mode 0, no rewind + ... + 160 = /dev/nst0l First SCSI tape, mode 1, no rewind + 161 = /dev/nst1l Second SCSI tape, mode 1, no rewind + ... + 192 = /dev/nst0m First SCSI tape, mode 2, no rewind + 193 = /dev/nst1m Second SCSI tape, mode 2, no rewind + ... + 224 = /dev/nst0a First SCSI tape, mode 3, no rewind + 225 = /dev/nst1a Second SCSI tape, mode 3, no rewind + ... + + "No rewind" refers to the omission of the default + automatic rewind on device close. The MTREW or MTOFFL + ioctl()'s can be used to rewind the tape regardless of + the device used to access it. + + 9 block Metadisk (RAID) devices + 0 = /dev/md0 First metadisk group + 1 = /dev/md1 Second metadisk group + ... + + The metadisk driver is used to span a + filesystem across multiple physical disks. + + 10 char Non-serial mice, misc features + 0 = /dev/logibm Logitech bus mouse + 1 = /dev/psaux PS/2-style mouse port + 2 = /dev/inportbm Microsoft Inport bus mouse + 3 = /dev/atibm ATI XL bus mouse + 4 = /dev/jbm J-mouse + 4 = /dev/amigamouse Amiga mouse (68k/Amiga) + 5 = /dev/atarimouse Atari mouse + 6 = /dev/sunmouse Sun mouse + 7 = /dev/amigamouse1 Second Amiga mouse + 8 = /dev/smouse Simple serial mouse driver + 9 = /dev/pc110pad IBM PC-110 digitizer pad + 10 = /dev/adbmouse Apple Desktop Bus mouse + 11 = /dev/vrtpanel Vr41xx embedded touch panel + 13 = /dev/vpcmouse Connectix Virtual PC Mouse + 14 = /dev/touchscreen/ucb1x00 UCB 1x00 touchscreen + 15 = /dev/touchscreen/mk712 MK712 touchscreen + 128 = /dev/beep Fancy beep device + 129 = + 130 = /dev/watchdog Watchdog timer port + 131 = /dev/temperature Machine internal temperature + 132 = /dev/hwtrap Hardware fault trap + 133 = /dev/exttrp External device trap + 134 = /dev/apm_bios Advanced Power Management BIOS + 135 = /dev/rtc Real Time Clock + 137 = /dev/vhci Bluetooth virtual HCI driver + 139 = /dev/openprom SPARC OpenBoot PROM + 140 = /dev/relay8 Berkshire Products Octal relay card + 141 = /dev/relay16 Berkshire Products ISO-16 relay card + 142 = + 143 = /dev/pciconf PCI configuration space + 144 = /dev/nvram Non-volatile configuration RAM + 145 = /dev/hfmodem Soundcard shortwave modem control + 146 = /dev/graphics Linux/SGI graphics device + 147 = /dev/opengl Linux/SGI OpenGL pipe + 148 = /dev/gfx Linux/SGI graphics effects device + 149 = /dev/input/mouse Linux/SGI Irix emulation mouse + 150 = /dev/input/keyboard Linux/SGI Irix emulation keyboard + 151 = /dev/led Front panel LEDs + 152 = /dev/kpoll Kernel Poll Driver + 153 = /dev/mergemem Memory merge device + 154 = /dev/pmu Macintosh PowerBook power manager + 155 = /dev/isictl MultiTech ISICom serial control + 156 = /dev/lcd Front panel LCD display + 157 = /dev/ac Applicom Intl Profibus card + 158 = /dev/nwbutton Netwinder external button + 159 = /dev/nwdebug Netwinder debug interface + 160 = /dev/nwflash Netwinder flash memory + 161 = /dev/userdma User-space DMA access + 162 = /dev/smbus System Management Bus + 163 = /dev/lik Logitech Internet Keyboard + 164 = /dev/ipmo Intel Intelligent Platform Management + 165 = /dev/vmmon VMware virtual machine monitor + 166 = /dev/i2o/ctl I2O configuration manager + 167 = /dev/specialix_sxctl Specialix serial control + 168 = /dev/tcldrv Technology Concepts serial control + 169 = /dev/specialix_rioctl Specialix RIO serial control + 170 = /dev/thinkpad/thinkpad IBM Thinkpad devices + 171 = /dev/srripc QNX4 API IPC manager + 172 = /dev/usemaclone Semaphore clone device + 173 = /dev/ipmikcs Intelligent Platform Management + 174 = /dev/uctrl SPARCbook 3 microcontroller + 175 = /dev/agpgart AGP Graphics Address Remapping Table + 176 = /dev/gtrsc Gorgy Timing radio clock + 177 = /dev/cbm Serial CBM bus + 178 = /dev/jsflash JavaStation OS flash SIMM + 179 = /dev/xsvc High-speed shared-mem/semaphore service + 180 = /dev/vrbuttons Vr41xx button input device + 181 = /dev/toshiba Toshiba laptop SMM support + 182 = /dev/perfctr Performance-monitoring counters + 183 = /dev/hwrng Generic random number generator + 184 = /dev/cpu/microcode CPU microcode update interface + 186 = /dev/atomicps Atomic shapshot of process state data + 187 = /dev/irnet IrNET device + 188 = /dev/smbusbios SMBus BIOS + 189 = /dev/ussp_ctl User space serial port control + 190 = /dev/crash Mission Critical Linux crash dump facility + 191 = /dev/pcl181 <information missing> + 192 = /dev/nas_xbus NAS xbus LCD/buttons access + 193 = /dev/d7s SPARC 7-segment display + 194 = /dev/zkshim Zero-Knowledge network shim control + 195 = /dev/elographics/e2201 Elographics touchscreen E271-2201 + 196 = /dev/vfio/vfio VFIO userspace driver interface + 197 = /dev/pxa3xx-gcu PXA3xx graphics controller unit driver + 198 = /dev/sexec Signed executable interface + 199 = /dev/scanners/cuecat :CueCat barcode scanner + 200 = /dev/net/tun TAP/TUN network device + 201 = /dev/button/gulpb Transmeta GULP-B buttons + 202 = /dev/emd/ctl Enhanced Metadisk RAID (EMD) control + 203 = /dev/cuse Cuse (character device in user-space) + 204 = /dev/video/em8300 EM8300 DVD decoder control + 205 = /dev/video/em8300_mv EM8300 DVD decoder video + 206 = /dev/video/em8300_ma EM8300 DVD decoder audio + 207 = /dev/video/em8300_sp EM8300 DVD decoder subpicture + 208 = /dev/compaq/cpqphpc Compaq PCI Hot Plug Controller + 209 = /dev/compaq/cpqrid Compaq Remote Insight Driver + 210 = /dev/impi/bt IMPI coprocessor block transfer + 211 = /dev/impi/smic IMPI coprocessor stream interface + 212 = /dev/watchdogs/0 First watchdog device + 213 = /dev/watchdogs/1 Second watchdog device + 214 = /dev/watchdogs/2 Third watchdog device + 215 = /dev/watchdogs/3 Fourth watchdog device + 216 = /dev/fujitsu/apanel Fujitsu/Siemens application panel + 217 = /dev/ni/natmotn National Instruments Motion + 218 = /dev/kchuid Inter-process chuid control + 219 = /dev/modems/mwave MWave modem firmware upload + 220 = /dev/mptctl Message passing technology (MPT) control + 221 = /dev/mvista/hssdsi Montavista PICMG hot swap system driver + 222 = /dev/mvista/hasi Montavista PICMG high availability + 223 = /dev/input/uinput User level driver support for input + 224 = /dev/tpm TCPA TPM driver + 225 = /dev/pps Pulse Per Second driver + 226 = /dev/systrace Systrace device + 227 = /dev/mcelog X86_64 Machine Check Exception driver + 228 = /dev/hpet HPET driver + 229 = /dev/fuse Fuse (virtual filesystem in user-space) + 230 = /dev/midishare MidiShare driver + 231 = /dev/snapshot System memory snapshot device + 232 = /dev/kvm Kernel-based virtual machine (hardware virtualization extensions) + 233 = /dev/kmview View-OS A process with a view + 234 = /dev/btrfs-control Btrfs control device + 235 = /dev/autofs Autofs control device + 236 = /dev/mapper/control Device-Mapper control device + 237 = /dev/loop-control Loopback control device + 238 = /dev/vhost-net Host kernel accelerator for virtio net + 239 = /dev/uhid User-space I/O driver support for HID subsystem + + 240-254 Reserved for local use + 255 Reserved for MISC_DYNAMIC_MINOR + + 11 char Raw keyboard device (Linux/SPARC only) + 0 = /dev/kbd Raw keyboard device + + 11 char Serial Mux device (Linux/PA-RISC only) + 0 = /dev/ttyB0 First mux port + 1 = /dev/ttyB1 Second mux port + ... + + 11 block SCSI CD-ROM devices + 0 = /dev/scd0 First SCSI CD-ROM + 1 = /dev/scd1 Second SCSI CD-ROM + ... + + The prefix /dev/sr (instead of /dev/scd) has been deprecated. + + 12 char QIC-02 tape + 2 = /dev/ntpqic11 QIC-11, no rewind-on-close + 3 = /dev/tpqic11 QIC-11, rewind-on-close + 4 = /dev/ntpqic24 QIC-24, no rewind-on-close + 5 = /dev/tpqic24 QIC-24, rewind-on-close + 6 = /dev/ntpqic120 QIC-120, no rewind-on-close + 7 = /dev/tpqic120 QIC-120, rewind-on-close + 8 = /dev/ntpqic150 QIC-150, no rewind-on-close + 9 = /dev/tpqic150 QIC-150, rewind-on-close + + The device names specified are proposed -- if there + are "standard" names for these devices, please let me know. + + 12 block + + 13 char Input core + 0 = /dev/input/js0 First joystick + 1 = /dev/input/js1 Second joystick + ... + 32 = /dev/input/mouse0 First mouse + 33 = /dev/input/mouse1 Second mouse + ... + 63 = /dev/input/mice Unified mouse + 64 = /dev/input/event0 First event queue + 65 = /dev/input/event1 Second event queue + ... + + Each device type has 5 bits (32 minors). + + 13 block Previously used for the XT disk (/dev/xdN) + Deleted in kernel v3.9. + + 14 char Open Sound System (OSS) + 0 = /dev/mixer Mixer control + 1 = /dev/sequencer Audio sequencer + 2 = /dev/midi00 First MIDI port + 3 = /dev/dsp Digital audio + 4 = /dev/audio Sun-compatible digital audio + 6 = + 7 = /dev/audioctl SPARC audio control device + 8 = /dev/sequencer2 Sequencer -- alternate device + 16 = /dev/mixer1 Second soundcard mixer control + 17 = /dev/patmgr0 Sequencer patch manager + 18 = /dev/midi01 Second MIDI port + 19 = /dev/dsp1 Second soundcard digital audio + 20 = /dev/audio1 Second soundcard Sun digital audio + 33 = /dev/patmgr1 Sequencer patch manager + 34 = /dev/midi02 Third MIDI port + 50 = /dev/midi03 Fourth MIDI port + + 14 block + + 15 char Joystick + 0 = /dev/js0 First analog joystick + 1 = /dev/js1 Second analog joystick + ... + 128 = /dev/djs0 First digital joystick + 129 = /dev/djs1 Second digital joystick + ... + 15 block Sony CDU-31A/CDU-33A CD-ROM + 0 = /dev/sonycd Sony CDU-31a CD-ROM + + 16 char Non-SCSI scanners + 0 = /dev/gs4500 Genius 4500 handheld scanner + + 16 block GoldStar CD-ROM + 0 = /dev/gscd GoldStar CD-ROM + + 17 char OBSOLETE (was Chase serial card) + 0 = /dev/ttyH0 First Chase port + 1 = /dev/ttyH1 Second Chase port + ... + 17 block Optics Storage CD-ROM + 0 = /dev/optcd Optics Storage CD-ROM + + 18 char OBSOLETE (was Chase serial card - alternate devices) + 0 = /dev/cuh0 Callout device for ttyH0 + 1 = /dev/cuh1 Callout device for ttyH1 + ... + 18 block Sanyo CD-ROM + 0 = /dev/sjcd Sanyo CD-ROM + + 19 char Cyclades serial card + 0 = /dev/ttyC0 First Cyclades port + ... + 31 = /dev/ttyC31 32nd Cyclades port + + 19 block "Double" compressed disk + 0 = /dev/double0 First compressed disk + ... + 7 = /dev/double7 Eighth compressed disk + 128 = /dev/cdouble0 Mirror of first compressed disk + ... + 135 = /dev/cdouble7 Mirror of eighth compressed disk + + See the Double documentation for the meaning of the + mirror devices. + + 20 char Cyclades serial card - alternate devices + 0 = /dev/cub0 Callout device for ttyC0 + ... + 31 = /dev/cub31 Callout device for ttyC31 + + 20 block Hitachi CD-ROM (under development) + 0 = /dev/hitcd Hitachi CD-ROM + + 21 char Generic SCSI access + 0 = /dev/sg0 First generic SCSI device + 1 = /dev/sg1 Second generic SCSI device + ... + + Most distributions name these /dev/sga, /dev/sgb...; + this sets an unnecessary limit of 26 SCSI devices in + the system and is counter to standard Linux + device-naming practice. + + 21 block Acorn MFM hard drive interface + 0 = /dev/mfma First MFM drive whole disk + 64 = /dev/mfmb Second MFM drive whole disk + + This device is used on the ARM-based Acorn RiscPC. + Partitions are handled the same way as for IDE disks + (see major number 3). + + 22 char Digiboard serial card + 0 = /dev/ttyD0 First Digiboard port + 1 = /dev/ttyD1 Second Digiboard port + ... + 22 block Second IDE hard disk/CD-ROM interface + 0 = /dev/hdc Master: whole disk (or CD-ROM) + 64 = /dev/hdd Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 23 char Digiboard serial card - alternate devices + 0 = /dev/cud0 Callout device for ttyD0 + 1 = /dev/cud1 Callout device for ttyD1 + ... + 23 block Mitsumi proprietary CD-ROM + 0 = /dev/mcd Mitsumi CD-ROM + + 24 char Stallion serial card + 0 = /dev/ttyE0 Stallion port 0 card 0 + 1 = /dev/ttyE1 Stallion port 1 card 0 + ... + 64 = /dev/ttyE64 Stallion port 0 card 1 + 65 = /dev/ttyE65 Stallion port 1 card 1 + ... + 128 = /dev/ttyE128 Stallion port 0 card 2 + 129 = /dev/ttyE129 Stallion port 1 card 2 + ... + 192 = /dev/ttyE192 Stallion port 0 card 3 + 193 = /dev/ttyE193 Stallion port 1 card 3 + ... + 24 block Sony CDU-535 CD-ROM + 0 = /dev/cdu535 Sony CDU-535 CD-ROM + + 25 char Stallion serial card - alternate devices + 0 = /dev/cue0 Callout device for ttyE0 + 1 = /dev/cue1 Callout device for ttyE1 + ... + 64 = /dev/cue64 Callout device for ttyE64 + 65 = /dev/cue65 Callout device for ttyE65 + ... + 128 = /dev/cue128 Callout device for ttyE128 + 129 = /dev/cue129 Callout device for ttyE129 + ... + 192 = /dev/cue192 Callout device for ttyE192 + 193 = /dev/cue193 Callout device for ttyE193 + ... + 25 block First Matsushita (Panasonic/SoundBlaster) CD-ROM + 0 = /dev/sbpcd0 Panasonic CD-ROM controller 0 unit 0 + 1 = /dev/sbpcd1 Panasonic CD-ROM controller 0 unit 1 + 2 = /dev/sbpcd2 Panasonic CD-ROM controller 0 unit 2 + 3 = /dev/sbpcd3 Panasonic CD-ROM controller 0 unit 3 + + 26 char + + 26 block Second Matsushita (Panasonic/SoundBlaster) CD-ROM + 0 = /dev/sbpcd4 Panasonic CD-ROM controller 1 unit 0 + 1 = /dev/sbpcd5 Panasonic CD-ROM controller 1 unit 1 + 2 = /dev/sbpcd6 Panasonic CD-ROM controller 1 unit 2 + 3 = /dev/sbpcd7 Panasonic CD-ROM controller 1 unit 3 + + 27 char QIC-117 tape + 0 = /dev/qft0 Unit 0, rewind-on-close + 1 = /dev/qft1 Unit 1, rewind-on-close + 2 = /dev/qft2 Unit 2, rewind-on-close + 3 = /dev/qft3 Unit 3, rewind-on-close + 4 = /dev/nqft0 Unit 0, no rewind-on-close + 5 = /dev/nqft1 Unit 1, no rewind-on-close + 6 = /dev/nqft2 Unit 2, no rewind-on-close + 7 = /dev/nqft3 Unit 3, no rewind-on-close + 16 = /dev/zqft0 Unit 0, rewind-on-close, compression + 17 = /dev/zqft1 Unit 1, rewind-on-close, compression + 18 = /dev/zqft2 Unit 2, rewind-on-close, compression + 19 = /dev/zqft3 Unit 3, rewind-on-close, compression + 20 = /dev/nzqft0 Unit 0, no rewind-on-close, compression + 21 = /dev/nzqft1 Unit 1, no rewind-on-close, compression + 22 = /dev/nzqft2 Unit 2, no rewind-on-close, compression + 23 = /dev/nzqft3 Unit 3, no rewind-on-close, compression + 32 = /dev/rawqft0 Unit 0, rewind-on-close, no file marks + 33 = /dev/rawqft1 Unit 1, rewind-on-close, no file marks + 34 = /dev/rawqft2 Unit 2, rewind-on-close, no file marks + 35 = /dev/rawqft3 Unit 3, rewind-on-close, no file marks + 36 = /dev/nrawqft0 Unit 0, no rewind-on-close, no file marks + 37 = /dev/nrawqft1 Unit 1, no rewind-on-close, no file marks + 38 = /dev/nrawqft2 Unit 2, no rewind-on-close, no file marks + 39 = /dev/nrawqft3 Unit 3, no rewind-on-close, no file marks + + 27 block Third Matsushita (Panasonic/SoundBlaster) CD-ROM + 0 = /dev/sbpcd8 Panasonic CD-ROM controller 2 unit 0 + 1 = /dev/sbpcd9 Panasonic CD-ROM controller 2 unit 1 + 2 = /dev/sbpcd10 Panasonic CD-ROM controller 2 unit 2 + 3 = /dev/sbpcd11 Panasonic CD-ROM controller 2 unit 3 + + 28 char Stallion serial card - card programming + 0 = /dev/staliomem0 First Stallion card I/O memory + 1 = /dev/staliomem1 Second Stallion card I/O memory + 2 = /dev/staliomem2 Third Stallion card I/O memory + 3 = /dev/staliomem3 Fourth Stallion card I/O memory + + 28 char Atari SLM ACSI laser printer (68k/Atari) + 0 = /dev/slm0 First SLM laser printer + 1 = /dev/slm1 Second SLM laser printer + ... + 28 block Fourth Matsushita (Panasonic/SoundBlaster) CD-ROM + 0 = /dev/sbpcd12 Panasonic CD-ROM controller 3 unit 0 + 1 = /dev/sbpcd13 Panasonic CD-ROM controller 3 unit 1 + 2 = /dev/sbpcd14 Panasonic CD-ROM controller 3 unit 2 + 3 = /dev/sbpcd15 Panasonic CD-ROM controller 3 unit 3 + + 28 block ACSI disk (68k/Atari) + 0 = /dev/ada First ACSI disk whole disk + 16 = /dev/adb Second ACSI disk whole disk + 32 = /dev/adc Third ACSI disk whole disk + ... + 240 = /dev/adp 16th ACSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15, like SCSI. + + 29 char Universal frame buffer + 0 = /dev/fb0 First frame buffer + 1 = /dev/fb1 Second frame buffer + ... + 31 = /dev/fb31 32nd frame buffer + + 29 block Aztech/Orchid/Okano/Wearnes CD-ROM + 0 = /dev/aztcd Aztech CD-ROM + + 30 char iBCS-2 compatibility devices + 0 = /dev/socksys Socket access + 1 = /dev/spx SVR3 local X interface + 32 = /dev/inet/ip Network access + 33 = /dev/inet/icmp + 34 = /dev/inet/ggp + 35 = /dev/inet/ipip + 36 = /dev/inet/tcp + 37 = /dev/inet/egp + 38 = /dev/inet/pup + 39 = /dev/inet/udp + 40 = /dev/inet/idp + 41 = /dev/inet/rawip + + Additionally, iBCS-2 requires the following links: + + /dev/ip -> /dev/inet/ip + /dev/icmp -> /dev/inet/icmp + /dev/ggp -> /dev/inet/ggp + /dev/ipip -> /dev/inet/ipip + /dev/tcp -> /dev/inet/tcp + /dev/egp -> /dev/inet/egp + /dev/pup -> /dev/inet/pup + /dev/udp -> /dev/inet/udp + /dev/idp -> /dev/inet/idp + /dev/rawip -> /dev/inet/rawip + /dev/inet/arp -> /dev/inet/udp + /dev/inet/rip -> /dev/inet/udp + /dev/nfsd -> /dev/socksys + /dev/X0R -> /dev/null (? apparently not required ?) + + 30 block Philips LMS CM-205 CD-ROM + 0 = /dev/cm205cd Philips LMS CM-205 CD-ROM + + /dev/lmscd is an older name for this device. This + driver does not work with the CM-205MS CD-ROM. + + 31 char MPU-401 MIDI + 0 = /dev/mpu401data MPU-401 data port + 1 = /dev/mpu401stat MPU-401 status port + + 31 block ROM/flash memory card + 0 = /dev/rom0 First ROM card (rw) + ... + 7 = /dev/rom7 Eighth ROM card (rw) + 8 = /dev/rrom0 First ROM card (ro) + ... + 15 = /dev/rrom7 Eighth ROM card (ro) + 16 = /dev/flash0 First flash memory card (rw) + ... + 23 = /dev/flash7 Eighth flash memory card (rw) + 24 = /dev/rflash0 First flash memory card (ro) + ... + 31 = /dev/rflash7 Eighth flash memory card (ro) + + The read-write (rw) devices support back-caching + written data in RAM, as well as writing to flash RAM + devices. The read-only devices (ro) support reading + only. + + 32 char Specialix serial card + 0 = /dev/ttyX0 First Specialix port + 1 = /dev/ttyX1 Second Specialix port + ... + 32 block Philips LMS CM-206 CD-ROM + 0 = /dev/cm206cd Philips LMS CM-206 CD-ROM + + 33 char Specialix serial card - alternate devices + 0 = /dev/cux0 Callout device for ttyX0 + 1 = /dev/cux1 Callout device for ttyX1 + ... + 33 block Third IDE hard disk/CD-ROM interface + 0 = /dev/hde Master: whole disk (or CD-ROM) + 64 = /dev/hdf Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 34 char Z8530 HDLC driver + 0 = /dev/scc0 First Z8530, first port + 1 = /dev/scc1 First Z8530, second port + 2 = /dev/scc2 Second Z8530, first port + 3 = /dev/scc3 Second Z8530, second port + ... + + In a previous version these devices were named + /dev/sc1 for /dev/scc0, /dev/sc2 for /dev/scc1, and so + on. + + 34 block Fourth IDE hard disk/CD-ROM interface + 0 = /dev/hdg Master: whole disk (or CD-ROM) + 64 = /dev/hdh Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 35 char tclmidi MIDI driver + 0 = /dev/midi0 First MIDI port, kernel timed + 1 = /dev/midi1 Second MIDI port, kernel timed + 2 = /dev/midi2 Third MIDI port, kernel timed + 3 = /dev/midi3 Fourth MIDI port, kernel timed + 64 = /dev/rmidi0 First MIDI port, untimed + 65 = /dev/rmidi1 Second MIDI port, untimed + 66 = /dev/rmidi2 Third MIDI port, untimed + 67 = /dev/rmidi3 Fourth MIDI port, untimed + 128 = /dev/smpte0 First MIDI port, SMPTE timed + 129 = /dev/smpte1 Second MIDI port, SMPTE timed + 130 = /dev/smpte2 Third MIDI port, SMPTE timed + 131 = /dev/smpte3 Fourth MIDI port, SMPTE timed + + 35 block Slow memory ramdisk + 0 = /dev/slram Slow memory ramdisk + + 36 char Netlink support + 0 = /dev/route Routing, device updates, kernel to user + 1 = /dev/skip enSKIP security cache control + 3 = /dev/fwmonitor Firewall packet copies + 16 = /dev/tap0 First Ethertap device + ... + 31 = /dev/tap15 16th Ethertap device + + 36 block OBSOLETE (was MCA ESDI hard disk) + + 37 char IDE tape + 0 = /dev/ht0 First IDE tape + 1 = /dev/ht1 Second IDE tape + ... + 128 = /dev/nht0 First IDE tape, no rewind-on-close + 129 = /dev/nht1 Second IDE tape, no rewind-on-close + ... + + Currently, only one IDE tape drive is supported. + + 37 block Zorro II ramdisk + 0 = /dev/z2ram Zorro II ramdisk + + 38 char Myricom PCI Myrinet board + 0 = /dev/mlanai0 First Myrinet board + 1 = /dev/mlanai1 Second Myrinet board + ... + + This device is used for status query, board control + and "user level packet I/O." This board is also + accessible as a standard networking "eth" device. + + 38 block OBSOLETE (was Linux/AP+) + + 39 char ML-16P experimental I/O board + 0 = /dev/ml16pa-a0 First card, first analog channel + 1 = /dev/ml16pa-a1 First card, second analog channel + ... + 15 = /dev/ml16pa-a15 First card, 16th analog channel + 16 = /dev/ml16pa-d First card, digital lines + 17 = /dev/ml16pa-c0 First card, first counter/timer + 18 = /dev/ml16pa-c1 First card, second counter/timer + 19 = /dev/ml16pa-c2 First card, third counter/timer + 32 = /dev/ml16pb-a0 Second card, first analog channel + 33 = /dev/ml16pb-a1 Second card, second analog channel + ... + 47 = /dev/ml16pb-a15 Second card, 16th analog channel + 48 = /dev/ml16pb-d Second card, digital lines + 49 = /dev/ml16pb-c0 Second card, first counter/timer + 50 = /dev/ml16pb-c1 Second card, second counter/timer + 51 = /dev/ml16pb-c2 Second card, third counter/timer + ... + 39 block + + 40 char + + 40 block + + 41 char Yet Another Micro Monitor + 0 = /dev/yamm Yet Another Micro Monitor + + 41 block + + 42 char Demo/sample use + + 42 block Demo/sample use + + This number is intended for use in sample code, as + well as a general "example" device number. It + should never be used for a device driver that is being + distributed; either obtain an official number or use + the local/experimental range. The sudden addition or + removal of a driver with this number should not cause + ill effects to the system (bugs excepted.) + + IN PARTICULAR, ANY DISTRIBUTION WHICH CONTAINS A + DEVICE DRIVER USING MAJOR NUMBER 42 IS NONCOMPLIANT. + + 43 char isdn4linux virtual modem + 0 = /dev/ttyI0 First virtual modem + ... + 63 = /dev/ttyI63 64th virtual modem + + 43 block Network block devices + 0 = /dev/nb0 First network block device + 1 = /dev/nb1 Second network block device + ... + + Network Block Device is somehow similar to loopback + devices: If you read from it, it sends packet across + network asking server for data. If you write to it, it + sends packet telling server to write. It could be used + to mounting filesystems over the net, swapping over + the net, implementing block device in userland etc. + + 44 char isdn4linux virtual modem - alternate devices + 0 = /dev/cui0 Callout device for ttyI0 + ... + 63 = /dev/cui63 Callout device for ttyI63 + + 44 block Flash Translation Layer (FTL) filesystems + 0 = /dev/ftla FTL on first Memory Technology Device + 16 = /dev/ftlb FTL on second Memory Technology Device + 32 = /dev/ftlc FTL on third Memory Technology Device + ... + 240 = /dev/ftlp FTL on 16th Memory Technology Device + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the partition + limit is 15 rather than 63 per disk (same as SCSI.) + + 45 char isdn4linux ISDN BRI driver + 0 = /dev/isdn0 First virtual B channel raw data + ... + 63 = /dev/isdn63 64th virtual B channel raw data + 64 = /dev/isdnctrl0 First channel control/debug + ... + 127 = /dev/isdnctrl63 64th channel control/debug + + 128 = /dev/ippp0 First SyncPPP device + ... + 191 = /dev/ippp63 64th SyncPPP device + + 255 = /dev/isdninfo ISDN monitor interface + + 45 block Parallel port IDE disk devices + 0 = /dev/pda First parallel port IDE disk + 16 = /dev/pdb Second parallel port IDE disk + 32 = /dev/pdc Third parallel port IDE disk + 48 = /dev/pdd Fourth parallel port IDE disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the partition + limit is 15 rather than 63 per disk. + + 46 char Comtrol Rocketport serial card + 0 = /dev/ttyR0 First Rocketport port + 1 = /dev/ttyR1 Second Rocketport port + ... + 46 block Parallel port ATAPI CD-ROM devices + 0 = /dev/pcd0 First parallel port ATAPI CD-ROM + 1 = /dev/pcd1 Second parallel port ATAPI CD-ROM + 2 = /dev/pcd2 Third parallel port ATAPI CD-ROM + 3 = /dev/pcd3 Fourth parallel port ATAPI CD-ROM + + 47 char Comtrol Rocketport serial card - alternate devices + 0 = /dev/cur0 Callout device for ttyR0 + 1 = /dev/cur1 Callout device for ttyR1 + ... + 47 block Parallel port ATAPI disk devices + 0 = /dev/pf0 First parallel port ATAPI disk + 1 = /dev/pf1 Second parallel port ATAPI disk + 2 = /dev/pf2 Third parallel port ATAPI disk + 3 = /dev/pf3 Fourth parallel port ATAPI disk + + This driver is intended for floppy disks and similar + devices and hence does not support partitioning. + + 48 char SDL RISCom serial card + 0 = /dev/ttyL0 First RISCom port + 1 = /dev/ttyL1 Second RISCom port + ... + 48 block Mylex DAC960 PCI RAID controller; first controller + 0 = /dev/rd/c0d0 First disk, whole disk + 8 = /dev/rd/c0d1 Second disk, whole disk + ... + 248 = /dev/rd/c0d31 32nd disk, whole disk + + For partitions add: + 0 = /dev/rd/c?d? Whole disk + 1 = /dev/rd/c?d?p1 First partition + ... + 7 = /dev/rd/c?d?p7 Seventh partition + + 49 char SDL RISCom serial card - alternate devices + 0 = /dev/cul0 Callout device for ttyL0 + 1 = /dev/cul1 Callout device for ttyL1 + ... + 49 block Mylex DAC960 PCI RAID controller; second controller + 0 = /dev/rd/c1d0 First disk, whole disk + 8 = /dev/rd/c1d1 Second disk, whole disk + ... + 248 = /dev/rd/c1d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 50 char Reserved for GLINT + + 50 block Mylex DAC960 PCI RAID controller; third controller + 0 = /dev/rd/c2d0 First disk, whole disk + 8 = /dev/rd/c2d1 Second disk, whole disk + ... + 248 = /dev/rd/c2d31 32nd disk, whole disk + + 51 char Baycom radio modem OR Radio Tech BIM-XXX-RS232 radio modem + 0 = /dev/bc0 First Baycom radio modem + 1 = /dev/bc1 Second Baycom radio modem + ... + 51 block Mylex DAC960 PCI RAID controller; fourth controller + 0 = /dev/rd/c3d0 First disk, whole disk + 8 = /dev/rd/c3d1 Second disk, whole disk + ... + 248 = /dev/rd/c3d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 52 char Spellcaster DataComm/BRI ISDN card + 0 = /dev/dcbri0 First DataComm card + 1 = /dev/dcbri1 Second DataComm card + 2 = /dev/dcbri2 Third DataComm card + 3 = /dev/dcbri3 Fourth DataComm card + + 52 block Mylex DAC960 PCI RAID controller; fifth controller + 0 = /dev/rd/c4d0 First disk, whole disk + 8 = /dev/rd/c4d1 Second disk, whole disk + ... + 248 = /dev/rd/c4d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 53 char BDM interface for remote debugging MC683xx microcontrollers + 0 = /dev/pd_bdm0 PD BDM interface on lp0 + 1 = /dev/pd_bdm1 PD BDM interface on lp1 + 2 = /dev/pd_bdm2 PD BDM interface on lp2 + 4 = /dev/icd_bdm0 ICD BDM interface on lp0 + 5 = /dev/icd_bdm1 ICD BDM interface on lp1 + 6 = /dev/icd_bdm2 ICD BDM interface on lp2 + + This device is used for the interfacing to the MC683xx + microcontrollers via Background Debug Mode by use of a + Parallel Port interface. PD is the Motorola Public + Domain Interface and ICD is the commercial interface + by P&E. + + 53 block Mylex DAC960 PCI RAID controller; sixth controller + 0 = /dev/rd/c5d0 First disk, whole disk + 8 = /dev/rd/c5d1 Second disk, whole disk + ... + 248 = /dev/rd/c5d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 54 char Electrocardiognosis Holter serial card + 0 = /dev/holter0 First Holter port + 1 = /dev/holter1 Second Holter port + 2 = /dev/holter2 Third Holter port + + A custom serial card used by Electrocardiognosis SRL + <mseritan@ottonel.pub.ro> to transfer data from Holter + 24-hour heart monitoring equipment. + + 54 block Mylex DAC960 PCI RAID controller; seventh controller + 0 = /dev/rd/c6d0 First disk, whole disk + 8 = /dev/rd/c6d1 Second disk, whole disk + ... + 248 = /dev/rd/c6d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 55 char DSP56001 digital signal processor + 0 = /dev/dsp56k First DSP56001 + + 55 block Mylex DAC960 PCI RAID controller; eighth controller + 0 = /dev/rd/c7d0 First disk, whole disk + 8 = /dev/rd/c7d1 Second disk, whole disk + ... + 248 = /dev/rd/c7d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 56 char Apple Desktop Bus + 0 = /dev/adb ADB bus control + + Additional devices will be added to this number, all + starting with /dev/adb. + + 56 block Fifth IDE hard disk/CD-ROM interface + 0 = /dev/hdi Master: whole disk (or CD-ROM) + 64 = /dev/hdj Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 57 char Hayes ESP serial card + 0 = /dev/ttyP0 First ESP port + 1 = /dev/ttyP1 Second ESP port + ... + + 57 block Sixth IDE hard disk/CD-ROM interface + 0 = /dev/hdk Master: whole disk (or CD-ROM) + 64 = /dev/hdl Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 58 char Hayes ESP serial card - alternate devices + 0 = /dev/cup0 Callout device for ttyP0 + 1 = /dev/cup1 Callout device for ttyP1 + ... + + 58 block Reserved for logical volume manager + + 59 char sf firewall package + 0 = /dev/firewall Communication with sf kernel module + + 59 block Generic PDA filesystem device + 0 = /dev/pda0 First PDA device + 1 = /dev/pda1 Second PDA device + ... + + The pda devices are used to mount filesystems on + remote pda's (basically slow handheld machines with + proprietary OS's and limited memory and storage + running small fs translation drivers) through serial / + IRDA / parallel links. + + NAMING CONFLICT -- PROPOSED REVISED NAME /dev/rpda0 etc + + 60-63 char LOCAL/EXPERIMENTAL USE + + 60-63 block LOCAL/EXPERIMENTAL USE + Allocated for local/experimental use. For devices not + assigned official numbers, these ranges should be + used in order to avoid conflicting with future assignments. + + 64 char ENskip kernel encryption package + 0 = /dev/enskip Communication with ENskip kernel module + + 64 block Scramdisk/DriveCrypt encrypted devices + 0 = /dev/scramdisk/master Master node for ioctls + 1 = /dev/scramdisk/1 First encrypted device + 2 = /dev/scramdisk/2 Second encrypted device + ... + 255 = /dev/scramdisk/255 255th encrypted device + + The filename of the encrypted container and the passwords + are sent via ioctls (using the sdmount tool) to the master + node which then activates them via one of the + /dev/scramdisk/x nodes for loop mounting (all handled + through the sdmount tool). + + Requested by: andy@scramdisklinux.org + + 65 char Sundance "plink" Transputer boards (obsolete, unused) + 0 = /dev/plink0 First plink device + 1 = /dev/plink1 Second plink device + 2 = /dev/plink2 Third plink device + 3 = /dev/plink3 Fourth plink device + 64 = /dev/rplink0 First plink device, raw + 65 = /dev/rplink1 Second plink device, raw + 66 = /dev/rplink2 Third plink device, raw + 67 = /dev/rplink3 Fourth plink device, raw + 128 = /dev/plink0d First plink device, debug + 129 = /dev/plink1d Second plink device, debug + 130 = /dev/plink2d Third plink device, debug + 131 = /dev/plink3d Fourth plink device, debug + 192 = /dev/rplink0d First plink device, raw, debug + 193 = /dev/rplink1d Second plink device, raw, debug + 194 = /dev/rplink2d Third plink device, raw, debug + 195 = /dev/rplink3d Fourth plink device, raw, debug + + This is a commercial driver; contact James Howes + <jth@prosig.demon.co.uk> for information. + + 65 block SCSI disk devices (16-31) + 0 = /dev/sdq 17th SCSI disk whole disk + 16 = /dev/sdr 18th SCSI disk whole disk + 32 = /dev/sds 19th SCSI disk whole disk + ... + 240 = /dev/sdaf 32nd SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 66 char YARC PowerPC PCI coprocessor card + 0 = /dev/yppcpci0 First YARC card + 1 = /dev/yppcpci1 Second YARC card + ... + + 66 block SCSI disk devices (32-47) + 0 = /dev/sdag 33th SCSI disk whole disk + 16 = /dev/sdah 34th SCSI disk whole disk + 32 = /dev/sdai 35th SCSI disk whole disk + ... + 240 = /dev/sdav 48nd SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 67 char Coda network file system + 0 = /dev/cfs0 Coda cache manager + + See http://www.coda.cs.cmu.edu for information about Coda. + + 67 block SCSI disk devices (48-63) + 0 = /dev/sdaw 49th SCSI disk whole disk + 16 = /dev/sdax 50th SCSI disk whole disk + 32 = /dev/sday 51st SCSI disk whole disk + ... + 240 = /dev/sdbl 64th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 68 char CAPI 2.0 interface + 0 = /dev/capi20 Control device + 1 = /dev/capi20.00 First CAPI 2.0 application + 2 = /dev/capi20.01 Second CAPI 2.0 application + ... + 20 = /dev/capi20.19 19th CAPI 2.0 application + + ISDN CAPI 2.0 driver for use with CAPI 2.0 + applications; currently supports the AVM B1 card. + + 68 block SCSI disk devices (64-79) + 0 = /dev/sdbm 65th SCSI disk whole disk + 16 = /dev/sdbn 66th SCSI disk whole disk + 32 = /dev/sdbo 67th SCSI disk whole disk + ... + 240 = /dev/sdcb 80th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 69 char MA16 numeric accelerator card + 0 = /dev/ma16 Board memory access + + 69 block SCSI disk devices (80-95) + 0 = /dev/sdcc 81st SCSI disk whole disk + 16 = /dev/sdcd 82nd SCSI disk whole disk + 32 = /dev/sdce 83th SCSI disk whole disk + ... + 240 = /dev/sdcr 96th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 70 char SpellCaster Protocol Services Interface + 0 = /dev/apscfg Configuration interface + 1 = /dev/apsauth Authentication interface + 2 = /dev/apslog Logging interface + 3 = /dev/apsdbg Debugging interface + 64 = /dev/apsisdn ISDN command interface + 65 = /dev/apsasync Async command interface + 128 = /dev/apsmon Monitor interface + + 70 block SCSI disk devices (96-111) + 0 = /dev/sdcs 97th SCSI disk whole disk + 16 = /dev/sdct 98th SCSI disk whole disk + 32 = /dev/sdcu 99th SCSI disk whole disk + ... + 240 = /dev/sddh 112nd SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 71 char Computone IntelliPort II serial card + 0 = /dev/ttyF0 IntelliPort II board 0, port 0 + 1 = /dev/ttyF1 IntelliPort II board 0, port 1 + ... + 63 = /dev/ttyF63 IntelliPort II board 0, port 63 + 64 = /dev/ttyF64 IntelliPort II board 1, port 0 + 65 = /dev/ttyF65 IntelliPort II board 1, port 1 + ... + 127 = /dev/ttyF127 IntelliPort II board 1, port 63 + 128 = /dev/ttyF128 IntelliPort II board 2, port 0 + 129 = /dev/ttyF129 IntelliPort II board 2, port 1 + ... + 191 = /dev/ttyF191 IntelliPort II board 2, port 63 + 192 = /dev/ttyF192 IntelliPort II board 3, port 0 + 193 = /dev/ttyF193 IntelliPort II board 3, port 1 + ... + 255 = /dev/ttyF255 IntelliPort II board 3, port 63 + + 71 block SCSI disk devices (112-127) + 0 = /dev/sddi 113th SCSI disk whole disk + 16 = /dev/sddj 114th SCSI disk whole disk + 32 = /dev/sddk 115th SCSI disk whole disk + ... + 240 = /dev/sddx 128th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 72 char Computone IntelliPort II serial card - alternate devices + 0 = /dev/cuf0 Callout device for ttyF0 + 1 = /dev/cuf1 Callout device for ttyF1 + ... + 63 = /dev/cuf63 Callout device for ttyF63 + 64 = /dev/cuf64 Callout device for ttyF64 + 65 = /dev/cuf65 Callout device for ttyF65 + ... + 127 = /dev/cuf127 Callout device for ttyF127 + 128 = /dev/cuf128 Callout device for ttyF128 + 129 = /dev/cuf129 Callout device for ttyF129 + ... + 191 = /dev/cuf191 Callout device for ttyF191 + 192 = /dev/cuf192 Callout device for ttyF192 + 193 = /dev/cuf193 Callout device for ttyF193 + ... + 255 = /dev/cuf255 Callout device for ttyF255 + + 72 block Compaq Intelligent Drive Array, first controller + 0 = /dev/ida/c0d0 First logical drive whole disk + 16 = /dev/ida/c0d1 Second logical drive whole disk + ... + 240 = /dev/ida/c0d15 16th logical drive whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 73 char Computone IntelliPort II serial card - control devices + 0 = /dev/ip2ipl0 Loadware device for board 0 + 1 = /dev/ip2stat0 Status device for board 0 + 4 = /dev/ip2ipl1 Loadware device for board 1 + 5 = /dev/ip2stat1 Status device for board 1 + 8 = /dev/ip2ipl2 Loadware device for board 2 + 9 = /dev/ip2stat2 Status device for board 2 + 12 = /dev/ip2ipl3 Loadware device for board 3 + 13 = /dev/ip2stat3 Status device for board 3 + + 73 block Compaq Intelligent Drive Array, second controller + 0 = /dev/ida/c1d0 First logical drive whole disk + 16 = /dev/ida/c1d1 Second logical drive whole disk + ... + 240 = /dev/ida/c1d15 16th logical drive whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 74 char SCI bridge + 0 = /dev/SCI/0 SCI device 0 + 1 = /dev/SCI/1 SCI device 1 + ... + + Currently for Dolphin Interconnect Solutions' PCI-SCI + bridge. + + 74 block Compaq Intelligent Drive Array, third controller + 0 = /dev/ida/c2d0 First logical drive whole disk + 16 = /dev/ida/c2d1 Second logical drive whole disk + ... + 240 = /dev/ida/c2d15 16th logical drive whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 75 char Specialix IO8+ serial card + 0 = /dev/ttyW0 First IO8+ port, first card + 1 = /dev/ttyW1 Second IO8+ port, first card + ... + 8 = /dev/ttyW8 First IO8+ port, second card + ... + + 75 block Compaq Intelligent Drive Array, fourth controller + 0 = /dev/ida/c3d0 First logical drive whole disk + 16 = /dev/ida/c3d1 Second logical drive whole disk + ... + 240 = /dev/ida/c3d15 16th logical drive whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 76 char Specialix IO8+ serial card - alternate devices + 0 = /dev/cuw0 Callout device for ttyW0 + 1 = /dev/cuw1 Callout device for ttyW1 + ... + 8 = /dev/cuw8 Callout device for ttyW8 + ... + + 76 block Compaq Intelligent Drive Array, fifth controller + 0 = /dev/ida/c4d0 First logical drive whole disk + 16 = /dev/ida/c4d1 Second logical drive whole disk + ... + 240 = /dev/ida/c4d15 16th logical drive whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + + 77 char ComScire Quantum Noise Generator + 0 = /dev/qng ComScire Quantum Noise Generator + + 77 block Compaq Intelligent Drive Array, sixth controller + 0 = /dev/ida/c5d0 First logical drive whole disk + 16 = /dev/ida/c5d1 Second logical drive whole disk + ... + 240 = /dev/ida/c5d15 16th logical drive whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 78 char PAM Software's multimodem boards + 0 = /dev/ttyM0 First PAM modem + 1 = /dev/ttyM1 Second PAM modem + ... + + 78 block Compaq Intelligent Drive Array, seventh controller + 0 = /dev/ida/c6d0 First logical drive whole disk + 16 = /dev/ida/c6d1 Second logical drive whole disk + ... + 240 = /dev/ida/c6d15 16th logical drive whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 79 char PAM Software's multimodem boards - alternate devices + 0 = /dev/cum0 Callout device for ttyM0 + 1 = /dev/cum1 Callout device for ttyM1 + ... + + 79 block Compaq Intelligent Drive Array, eighth controller + 0 = /dev/ida/c7d0 First logical drive whole disk + 16 = /dev/ida/c7d1 Second logical drive whole disk + ... + 240 = /dev/ida/c715 16th logical drive whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 80 char Photometrics AT200 CCD camera + 0 = /dev/at200 Photometrics AT200 CCD camera + + 80 block I2O hard disk + 0 = /dev/i2o/hda First I2O hard disk, whole disk + 16 = /dev/i2o/hdb Second I2O hard disk, whole disk + ... + 240 = /dev/i2o/hdp 16th I2O hard disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 81 char video4linux + 0 = /dev/video0 Video capture/overlay device + ... + 63 = /dev/video63 Video capture/overlay device + 64 = /dev/radio0 Radio device + ... + 127 = /dev/radio63 Radio device + 128 = /dev/swradio0 Software Defined Radio device + ... + 191 = /dev/swradio63 Software Defined Radio device + 224 = /dev/vbi0 Vertical blank interrupt + ... + 255 = /dev/vbi31 Vertical blank interrupt + + Minor numbers are allocated dynamically unless + CONFIG_VIDEO_FIXED_MINOR_RANGES (default n) + configuration option is set. + + 81 block I2O hard disk + 0 = /dev/i2o/hdq 17th I2O hard disk, whole disk + 16 = /dev/i2o/hdr 18th I2O hard disk, whole disk + ... + 240 = /dev/i2o/hdaf 32nd I2O hard disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 82 char WiNRADiO communications receiver card + 0 = /dev/winradio0 First WiNRADiO card + 1 = /dev/winradio1 Second WiNRADiO card + ... + + The driver and documentation may be obtained from + http://www.winradio.com/ + + 82 block I2O hard disk + 0 = /dev/i2o/hdag 33rd I2O hard disk, whole disk + 16 = /dev/i2o/hdah 34th I2O hard disk, whole disk + ... + 240 = /dev/i2o/hdav 48th I2O hard disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 83 char Matrox mga_vid video driver + 0 = /dev/mga_vid0 1st video card + 1 = /dev/mga_vid1 2nd video card + 2 = /dev/mga_vid2 3rd video card + ... + 15 = /dev/mga_vid15 16th video card + + 83 block I2O hard disk + 0 = /dev/i2o/hdaw 49th I2O hard disk, whole disk + 16 = /dev/i2o/hdax 50th I2O hard disk, whole disk + ... + 240 = /dev/i2o/hdbl 64th I2O hard disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 84 char Ikon 1011[57] Versatec Greensheet Interface + 0 = /dev/ihcp0 First Greensheet port + 1 = /dev/ihcp1 Second Greensheet port + + 84 block I2O hard disk + 0 = /dev/i2o/hdbm 65th I2O hard disk, whole disk + 16 = /dev/i2o/hdbn 66th I2O hard disk, whole disk + ... + 240 = /dev/i2o/hdcb 80th I2O hard disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 85 char Linux/SGI shared memory input queue + 0 = /dev/shmiq Master shared input queue + 1 = /dev/qcntl0 First device pushed + 2 = /dev/qcntl1 Second device pushed + ... + + 85 block I2O hard disk + 0 = /dev/i2o/hdcc 81st I2O hard disk, whole disk + 16 = /dev/i2o/hdcd 82nd I2O hard disk, whole disk + ... + 240 = /dev/i2o/hdcr 96th I2O hard disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 86 char SCSI media changer + 0 = /dev/sch0 First SCSI media changer + 1 = /dev/sch1 Second SCSI media changer + ... + + 86 block I2O hard disk + 0 = /dev/i2o/hdcs 97th I2O hard disk, whole disk + 16 = /dev/i2o/hdct 98th I2O hard disk, whole disk + ... + 240 = /dev/i2o/hddh 112th I2O hard disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 87 char Sony Control-A1 stereo control bus + 0 = /dev/controla0 First device on chain + 1 = /dev/controla1 Second device on chain + ... + + 87 block I2O hard disk + 0 = /dev/i2o/hddi 113rd I2O hard disk, whole disk + 16 = /dev/i2o/hddj 114th I2O hard disk, whole disk + ... + 240 = /dev/i2o/hddx 128th I2O hard disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 88 char COMX synchronous serial card + 0 = /dev/comx0 COMX channel 0 + 1 = /dev/comx1 COMX channel 1 + ... + + 88 block Seventh IDE hard disk/CD-ROM interface + 0 = /dev/hdm Master: whole disk (or CD-ROM) + 64 = /dev/hdn Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 89 char I2C bus interface + 0 = /dev/i2c-0 First I2C adapter + 1 = /dev/i2c-1 Second I2C adapter + ... + + 89 block Eighth IDE hard disk/CD-ROM interface + 0 = /dev/hdo Master: whole disk (or CD-ROM) + 64 = /dev/hdp Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 90 char Memory Technology Device (RAM, ROM, Flash) + 0 = /dev/mtd0 First MTD (rw) + 1 = /dev/mtdr0 First MTD (ro) + ... + 30 = /dev/mtd15 16th MTD (rw) + 31 = /dev/mtdr15 16th MTD (ro) + + 90 block Ninth IDE hard disk/CD-ROM interface + 0 = /dev/hdq Master: whole disk (or CD-ROM) + 64 = /dev/hdr Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 91 char CAN-Bus devices + 0 = /dev/can0 First CAN-Bus controller + 1 = /dev/can1 Second CAN-Bus controller + ... + + 91 block Tenth IDE hard disk/CD-ROM interface + 0 = /dev/hds Master: whole disk (or CD-ROM) + 64 = /dev/hdt Slave: whole disk (or CD-ROM) + + Partitions are handled the same way as for the first + interface (see major number 3). + + 92 char Reserved for ith Kommunikationstechnik MIC ISDN card + + 92 block PPDD encrypted disk driver + 0 = /dev/ppdd0 First encrypted disk + 1 = /dev/ppdd1 Second encrypted disk + ... + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 93 char + + 93 block NAND Flash Translation Layer filesystem + 0 = /dev/nftla First NFTL layer + 16 = /dev/nftlb Second NFTL layer + ... + 240 = /dev/nftlp 16th NTFL layer + + 94 char + + 94 block IBM S/390 DASD block storage + 0 = /dev/dasda First DASD device, major + 1 = /dev/dasda1 First DASD device, block 1 + 2 = /dev/dasda2 First DASD device, block 2 + 3 = /dev/dasda3 First DASD device, block 3 + 4 = /dev/dasdb Second DASD device, major + 5 = /dev/dasdb1 Second DASD device, block 1 + 6 = /dev/dasdb2 Second DASD device, block 2 + 7 = /dev/dasdb3 Second DASD device, block 3 + ... + + 95 char IP filter + 0 = /dev/ipl Filter control device/log file + 1 = /dev/ipnat NAT control device/log file + 2 = /dev/ipstate State information log file + 3 = /dev/ipauth Authentication control device/log file + ... + + 96 char Parallel port ATAPI tape devices + 0 = /dev/pt0 First parallel port ATAPI tape + 1 = /dev/pt1 Second parallel port ATAPI tape + ... + 128 = /dev/npt0 First p.p. ATAPI tape, no rewind + 129 = /dev/npt1 Second p.p. ATAPI tape, no rewind + ... + + 96 block Inverse NAND Flash Translation Layer + 0 = /dev/inftla First INFTL layer + 16 = /dev/inftlb Second INFTL layer + ... + 240 = /dev/inftlp 16th INTFL layer + + 97 char Parallel port generic ATAPI interface + 0 = /dev/pg0 First parallel port ATAPI device + 1 = /dev/pg1 Second parallel port ATAPI device + 2 = /dev/pg2 Third parallel port ATAPI device + 3 = /dev/pg3 Fourth parallel port ATAPI device + + These devices support the same API as the generic SCSI + devices. + + 98 char Control and Measurement Device (comedi) + 0 = /dev/comedi0 First comedi device + 1 = /dev/comedi1 Second comedi device + ... + + See http://stm.lbl.gov/comedi. + + 98 block User-mode virtual block device + 0 = /dev/ubda First user-mode block device + 16 = /dev/udbb Second user-mode block device + ... + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + This device is used by the user-mode virtual kernel port. + + 99 char Raw parallel ports + 0 = /dev/parport0 First parallel port + 1 = /dev/parport1 Second parallel port + ... + + 99 block JavaStation flash disk + 0 = /dev/jsfd JavaStation flash disk + + 100 char Telephony for Linux + 0 = /dev/phone0 First telephony device + 1 = /dev/phone1 Second telephony device + ... + + 101 char Motorola DSP 56xxx board + 0 = /dev/mdspstat Status information + 1 = /dev/mdsp1 First DSP board I/O controls + ... + 16 = /dev/mdsp16 16th DSP board I/O controls + + 101 block AMI HyperDisk RAID controller + 0 = /dev/amiraid/ar0 First array whole disk + 16 = /dev/amiraid/ar1 Second array whole disk + ... + 240 = /dev/amiraid/ar15 16th array whole disk + + For each device, partitions are added as: + 0 = /dev/amiraid/ar? Whole disk + 1 = /dev/amiraid/ar?p1 First partition + 2 = /dev/amiraid/ar?p2 Second partition + ... + 15 = /dev/amiraid/ar?p15 15th partition + + 102 char + + 102 block Compressed block device + 0 = /dev/cbd/a First compressed block device, whole device + 16 = /dev/cbd/b Second compressed block device, whole device + ... + 240 = /dev/cbd/p 16th compressed block device, whole device + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 103 char Arla network file system + 0 = /dev/nnpfs0 First NNPFS device + 1 = /dev/nnpfs1 Second NNPFS device + + Arla is a free clone of the Andrew File System, AFS. + The NNPFS device gives user mode filesystem + implementations a kernel presence for caching and easy + mounting. For more information about the project, + write to <arla-drinkers@stacken.kth.se> or see + http://www.stacken.kth.se/project/arla/ + + 103 block Audit device + 0 = /dev/audit Audit device + + 104 char Flash BIOS support + + 104 block Compaq Next Generation Drive Array, first controller + 0 = /dev/cciss/c0d0 First logical drive, whole disk + 16 = /dev/cciss/c0d1 Second logical drive, whole disk + ... + 240 = /dev/cciss/c0d15 16th logical drive, whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 105 char Comtrol VS-1000 serial controller + 0 = /dev/ttyV0 First VS-1000 port + 1 = /dev/ttyV1 Second VS-1000 port + ... + + 105 block Compaq Next Generation Drive Array, second controller + 0 = /dev/cciss/c1d0 First logical drive, whole disk + 16 = /dev/cciss/c1d1 Second logical drive, whole disk + ... + 240 = /dev/cciss/c1d15 16th logical drive, whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 106 char Comtrol VS-1000 serial controller - alternate devices + 0 = /dev/cuv0 First VS-1000 port + 1 = /dev/cuv1 Second VS-1000 port + ... + + 106 block Compaq Next Generation Drive Array, third controller + 0 = /dev/cciss/c2d0 First logical drive, whole disk + 16 = /dev/cciss/c2d1 Second logical drive, whole disk + ... + 240 = /dev/cciss/c2d15 16th logical drive, whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 107 char 3Dfx Voodoo Graphics device + 0 = /dev/3dfx Primary 3Dfx graphics device + + 107 block Compaq Next Generation Drive Array, fourth controller + 0 = /dev/cciss/c3d0 First logical drive, whole disk + 16 = /dev/cciss/c3d1 Second logical drive, whole disk + ... + 240 = /dev/cciss/c3d15 16th logical drive, whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 108 char Device independent PPP interface + 0 = /dev/ppp Device independent PPP interface + + 108 block Compaq Next Generation Drive Array, fifth controller + 0 = /dev/cciss/c4d0 First logical drive, whole disk + 16 = /dev/cciss/c4d1 Second logical drive, whole disk + ... + 240 = /dev/cciss/c4d15 16th logical drive, whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 109 char Reserved for logical volume manager + + 109 block Compaq Next Generation Drive Array, sixth controller + 0 = /dev/cciss/c5d0 First logical drive, whole disk + 16 = /dev/cciss/c5d1 Second logical drive, whole disk + ... + 240 = /dev/cciss/c5d15 16th logical drive, whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 110 char miroMEDIA Surround board + 0 = /dev/srnd0 First miroMEDIA Surround board + 1 = /dev/srnd1 Second miroMEDIA Surround board + ... + + 110 block Compaq Next Generation Drive Array, seventh controller + 0 = /dev/cciss/c6d0 First logical drive, whole disk + 16 = /dev/cciss/c6d1 Second logical drive, whole disk + ... + 240 = /dev/cciss/c6d15 16th logical drive, whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 111 char + + 111 block Compaq Next Generation Drive Array, eighth controller + 0 = /dev/cciss/c7d0 First logical drive, whole disk + 16 = /dev/cciss/c7d1 Second logical drive, whole disk + ... + 240 = /dev/cciss/c7d15 16th logical drive, whole disk + + Partitions are handled the same way as for Mylex + DAC960 (see major number 48) except that the limit on + partitions is 15. + + 112 char ISI serial card + 0 = /dev/ttyM0 First ISI port + 1 = /dev/ttyM1 Second ISI port + ... + + There is currently a device-naming conflict between + these and PAM multimodems (major 78). + + 112 block IBM iSeries virtual disk + 0 = /dev/iseries/vda First virtual disk, whole disk + 8 = /dev/iseries/vdb Second virtual disk, whole disk + ... + 200 = /dev/iseries/vdz 26th virtual disk, whole disk + 208 = /dev/iseries/vdaa 27th virtual disk, whole disk + ... + 248 = /dev/iseries/vdaf 32nd virtual disk, whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 7. + + 113 char ISI serial card - alternate devices + 0 = /dev/cum0 Callout device for ttyM0 + 1 = /dev/cum1 Callout device for ttyM1 + ... + + 113 block IBM iSeries virtual CD-ROM + 0 = /dev/iseries/vcda First virtual CD-ROM + 1 = /dev/iseries/vcdb Second virtual CD-ROM + ... + + 114 char Picture Elements ISE board + 0 = /dev/ise0 First ISE board + 1 = /dev/ise1 Second ISE board + ... + 128 = /dev/isex0 Control node for first ISE board + 129 = /dev/isex1 Control node for second ISE board + ... + + The ISE board is an embedded computer, optimized for + image processing. The /dev/iseN nodes are the general + I/O access to the board, the /dev/isex0 nodes command + nodes used to control the board. + + 114 block IDE BIOS powered software RAID interfaces such as the + Promise Fastrak + + 0 = /dev/ataraid/d0 + 1 = /dev/ataraid/d0p1 + 2 = /dev/ataraid/d0p2 + ... + 16 = /dev/ataraid/d1 + 17 = /dev/ataraid/d1p1 + 18 = /dev/ataraid/d1p2 + ... + 255 = /dev/ataraid/d15p15 + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 115 char TI link cable devices (115 was formerly the console driver speaker) + 0 = /dev/tipar0 Parallel cable on first parallel port + ... + 7 = /dev/tipar7 Parallel cable on seventh parallel port + + 8 = /dev/tiser0 Serial cable on first serial port + ... + 15 = /dev/tiser7 Serial cable on seventh serial port + + 16 = /dev/tiusb0 First USB cable + ... + 47 = /dev/tiusb31 32nd USB cable + + 115 block NetWare (NWFS) Devices (0-255) + + The NWFS (NetWare) devices are used to present a + collection of NetWare Mirror Groups or NetWare + Partitions as a logical storage segment for + use in mounting NetWare volumes. A maximum of + 256 NetWare volumes can be supported in a single + machine. + + http://cgfa.telepac.pt/ftp2/kernel.org/linux/kernel/people/jmerkey/nwfs/ + + 0 = /dev/nwfs/v0 First NetWare (NWFS) Logical Volume + 1 = /dev/nwfs/v1 Second NetWare (NWFS) Logical Volume + 2 = /dev/nwfs/v2 Third NetWare (NWFS) Logical Volume + ... + 255 = /dev/nwfs/v255 Last NetWare (NWFS) Logical Volume + + 116 char Advanced Linux Sound Driver (ALSA) + + 116 block MicroMemory battery backed RAM adapter (NVRAM) + Supports 16 boards, 15 partitions each. + Requested by neilb at cse.unsw.edu.au. + + 0 = /dev/umem/d0 Whole of first board + 1 = /dev/umem/d0p1 First partition of first board + 2 = /dev/umem/d0p2 Second partition of first board + 15 = /dev/umem/d0p15 15th partition of first board + + 16 = /dev/umem/d1 Whole of second board + 17 = /dev/umem/d1p1 First partition of second board + ... + 255= /dev/umem/d15p15 15th partition of 16th board. + + 117 char COSA/SRP synchronous serial card + 0 = /dev/cosa0c0 1st board, 1st channel + 1 = /dev/cosa0c1 1st board, 2nd channel + ... + 16 = /dev/cosa1c0 2nd board, 1st channel + 17 = /dev/cosa1c1 2nd board, 2nd channel + ... + + 117 block Enterprise Volume Management System (EVMS) + + The EVMS driver uses a layered, plug-in model to provide + unparalleled flexibility and extensibility in managing + storage. This allows for easy expansion or customization + of various levels of volume management. Requested by + Mark Peloquin (peloquin at us.ibm.com). + + Note: EVMS populates and manages all the devnodes in + /dev/evms. + + http://sf.net/projects/evms + + 0 = /dev/evms/block_device EVMS block device + 1 = /dev/evms/legacyname1 First EVMS legacy device + 2 = /dev/evms/legacyname2 Second EVMS legacy device + ... + Both ranges can grow (down or up) until they meet. + ... + 254 = /dev/evms/EVMSname2 Second EVMS native device + 255 = /dev/evms/EVMSname1 First EVMS native device + + Note: legacyname(s) are derived from the normal legacy + device names. For example, /dev/hda5 would become + /dev/evms/hda5. + + 118 char IBM Cryptographic Accelerator + 0 = /dev/ica Virtual interface to all IBM Crypto Accelerators + 1 = /dev/ica0 IBMCA Device 0 + 2 = /dev/ica1 IBMCA Device 1 + ... + + 119 char VMware virtual network control + 0 = /dev/vnet0 1st virtual network + 1 = /dev/vnet1 2nd virtual network + ... + + 120-127 char LOCAL/EXPERIMENTAL USE + + 120-127 block LOCAL/EXPERIMENTAL USE + Allocated for local/experimental use. For devices not + assigned official numbers, these ranges should be + used in order to avoid conflicting with future assignments. + + 128-135 char Unix98 PTY masters + + These devices should not have corresponding device + nodes; instead they should be accessed through the + /dev/ptmx cloning interface. + + 128 block SCSI disk devices (128-143) + 0 = /dev/sddy 129th SCSI disk whole disk + 16 = /dev/sddz 130th SCSI disk whole disk + 32 = /dev/sdea 131th SCSI disk whole disk + ... + 240 = /dev/sden 144th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 129 block SCSI disk devices (144-159) + 0 = /dev/sdeo 145th SCSI disk whole disk + 16 = /dev/sdep 146th SCSI disk whole disk + 32 = /dev/sdeq 147th SCSI disk whole disk + ... + 240 = /dev/sdfd 160th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 130 char (Misc devices) + + 130 block SCSI disk devices (160-175) + 0 = /dev/sdfe 161st SCSI disk whole disk + 16 = /dev/sdff 162nd SCSI disk whole disk + 32 = /dev/sdfg 163rd SCSI disk whole disk + ... + 240 = /dev/sdft 176th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 131 block SCSI disk devices (176-191) + 0 = /dev/sdfu 177th SCSI disk whole disk + 16 = /dev/sdfv 178th SCSI disk whole disk + 32 = /dev/sdfw 179th SCSI disk whole disk + ... + 240 = /dev/sdgj 192nd SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 132 block SCSI disk devices (192-207) + 0 = /dev/sdgk 193rd SCSI disk whole disk + 16 = /dev/sdgl 194th SCSI disk whole disk + 32 = /dev/sdgm 195th SCSI disk whole disk + ... + 240 = /dev/sdgz 208th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 133 block SCSI disk devices (208-223) + 0 = /dev/sdha 209th SCSI disk whole disk + 16 = /dev/sdhb 210th SCSI disk whole disk + 32 = /dev/sdhc 211th SCSI disk whole disk + ... + 240 = /dev/sdhp 224th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 134 block SCSI disk devices (224-239) + 0 = /dev/sdhq 225th SCSI disk whole disk + 16 = /dev/sdhr 226th SCSI disk whole disk + 32 = /dev/sdhs 227th SCSI disk whole disk + ... + 240 = /dev/sdif 240th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 135 block SCSI disk devices (240-255) + 0 = /dev/sdig 241st SCSI disk whole disk + 16 = /dev/sdih 242nd SCSI disk whole disk + 32 = /dev/sdih 243rd SCSI disk whole disk + ... + 240 = /dev/sdiv 256th SCSI disk whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 136-143 char Unix98 PTY slaves + 0 = /dev/pts/0 First Unix98 pseudo-TTY + 1 = /dev/pts/1 Second Unix98 pseudo-TTY + ... + + These device nodes are automatically generated with + the proper permissions and modes by mounting the + devpts filesystem onto /dev/pts with the appropriate + mount options (distribution dependent, however, on + *most* distributions the appropriate options are + "mode=0620,gid=<gid of the "tty" group>".) + + 136 block Mylex DAC960 PCI RAID controller; ninth controller + 0 = /dev/rd/c8d0 First disk, whole disk + 8 = /dev/rd/c8d1 Second disk, whole disk + ... + 248 = /dev/rd/c8d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 137 block Mylex DAC960 PCI RAID controller; tenth controller + 0 = /dev/rd/c9d0 First disk, whole disk + 8 = /dev/rd/c9d1 Second disk, whole disk + ... + 248 = /dev/rd/c9d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 138 block Mylex DAC960 PCI RAID controller; eleventh controller + 0 = /dev/rd/c10d0 First disk, whole disk + 8 = /dev/rd/c10d1 Second disk, whole disk + ... + 248 = /dev/rd/c10d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 139 block Mylex DAC960 PCI RAID controller; twelfth controller + 0 = /dev/rd/c11d0 First disk, whole disk + 8 = /dev/rd/c11d1 Second disk, whole disk + ... + 248 = /dev/rd/c11d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 140 block Mylex DAC960 PCI RAID controller; thirteenth controller + 0 = /dev/rd/c12d0 First disk, whole disk + 8 = /dev/rd/c12d1 Second disk, whole disk + ... + 248 = /dev/rd/c12d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 141 block Mylex DAC960 PCI RAID controller; fourteenth controller + 0 = /dev/rd/c13d0 First disk, whole disk + 8 = /dev/rd/c13d1 Second disk, whole disk + ... + 248 = /dev/rd/c13d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 142 block Mylex DAC960 PCI RAID controller; fifteenth controller + 0 = /dev/rd/c14d0 First disk, whole disk + 8 = /dev/rd/c14d1 Second disk, whole disk + ... + 248 = /dev/rd/c14d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 143 block Mylex DAC960 PCI RAID controller; sixteenth controller + 0 = /dev/rd/c15d0 First disk, whole disk + 8 = /dev/rd/c15d1 Second disk, whole disk + ... + 248 = /dev/rd/c15d31 32nd disk, whole disk + + Partitions are handled as for major 48. + + 144 char Encapsulated PPP + 0 = /dev/pppox0 First PPP over Ethernet + ... + 63 = /dev/pppox63 64th PPP over Ethernet + + This is primarily used for ADSL. + + The SST 5136-DN DeviceNet interface driver has been + relocated to major 183 due to an unfortunate conflict. + + 144 block Expansion Area #1 for more non-device (e.g. NFS) mounts + 0 = mounted device 256 + 255 = mounted device 511 + + 145 char SAM9407-based soundcard + 0 = /dev/sam0_mixer + 1 = /dev/sam0_sequencer + 2 = /dev/sam0_midi00 + 3 = /dev/sam0_dsp + 4 = /dev/sam0_audio + 6 = /dev/sam0_sndstat + 18 = /dev/sam0_midi01 + 34 = /dev/sam0_midi02 + 50 = /dev/sam0_midi03 + 64 = /dev/sam1_mixer + ... + 128 = /dev/sam2_mixer + ... + 192 = /dev/sam3_mixer + ... + + Device functions match OSS, but offer a number of + addons, which are sam9407 specific. OSS can be + operated simultaneously, taking care of the codec. + + 145 block Expansion Area #2 for more non-device (e.g. NFS) mounts + 0 = mounted device 512 + 255 = mounted device 767 + + 146 char SYSTRAM SCRAMNet mirrored-memory network + 0 = /dev/scramnet0 First SCRAMNet device + 1 = /dev/scramnet1 Second SCRAMNet device + ... + + 146 block Expansion Area #3 for more non-device (e.g. NFS) mounts + 0 = mounted device 768 + 255 = mounted device 1023 + + 147 char Aureal Semiconductor Vortex Audio device + 0 = /dev/aureal0 First Aureal Vortex + 1 = /dev/aureal1 Second Aureal Vortex + ... + + 147 block Distributed Replicated Block Device (DRBD) + 0 = /dev/drbd0 First DRBD device + 1 = /dev/drbd1 Second DRBD device + ... + + 148 char Technology Concepts serial card + 0 = /dev/ttyT0 First TCL port + 1 = /dev/ttyT1 Second TCL port + ... + + 149 char Technology Concepts serial card - alternate devices + 0 = /dev/cut0 Callout device for ttyT0 + 1 = /dev/cut0 Callout device for ttyT1 + ... + + 150 char Real-Time Linux FIFOs + 0 = /dev/rtf0 First RTLinux FIFO + 1 = /dev/rtf1 Second RTLinux FIFO + ... + + 151 char DPT I2O SmartRaid V controller + 0 = /dev/dpti0 First DPT I2O adapter + 1 = /dev/dpti1 Second DPT I2O adapter + ... + + 152 char EtherDrive Control Device + 0 = /dev/etherd/ctl Connect/Disconnect an EtherDrive + 1 = /dev/etherd/err Monitor errors + 2 = /dev/etherd/raw Raw AoE packet monitor + + 152 block EtherDrive Block Devices + 0 = /dev/etherd/0 EtherDrive 0 + ... + 255 = /dev/etherd/255 EtherDrive 255 + + 153 char SPI Bus Interface (sometimes referred to as MicroWire) + 0 = /dev/spi0 First SPI device on the bus + 1 = /dev/spi1 Second SPI device on the bus + ... + 15 = /dev/spi15 Sixteenth SPI device on the bus + + 153 block Enhanced Metadisk RAID (EMD) storage units + 0 = /dev/emd/0 First unit + 1 = /dev/emd/0p1 Partition 1 on First unit + 2 = /dev/emd/0p2 Partition 2 on First unit + ... + 15 = /dev/emd/0p15 Partition 15 on First unit + + 16 = /dev/emd/1 Second unit + 32 = /dev/emd/2 Third unit + ... + 240 = /dev/emd/15 Sixteenth unit + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 154 char Specialix RIO serial card + 0 = /dev/ttySR0 First RIO port + ... + 255 = /dev/ttySR255 256th RIO port + + 155 char Specialix RIO serial card - alternate devices + 0 = /dev/cusr0 Callout device for ttySR0 + ... + 255 = /dev/cusr255 Callout device for ttySR255 + + 156 char Specialix RIO serial card + 0 = /dev/ttySR256 257th RIO port + ... + 255 = /dev/ttySR511 512th RIO port + + 157 char Specialix RIO serial card - alternate devices + 0 = /dev/cusr256 Callout device for ttySR256 + ... + 255 = /dev/cusr511 Callout device for ttySR511 + + 158 char Dialogic GammaLink fax driver + 0 = /dev/gfax0 GammaLink channel 0 + 1 = /dev/gfax1 GammaLink channel 1 + ... + + 159 char RESERVED + + 159 block RESERVED + + 160 char General Purpose Instrument Bus (GPIB) + 0 = /dev/gpib0 First GPIB bus + 1 = /dev/gpib1 Second GPIB bus + ... + + 160 block Carmel 8-port SATA Disks on First Controller + 0 = /dev/carmel/0 SATA disk 0 whole disk + 1 = /dev/carmel/0p1 SATA disk 0 partition 1 + ... + 31 = /dev/carmel/0p31 SATA disk 0 partition 31 + + 32 = /dev/carmel/1 SATA disk 1 whole disk + 64 = /dev/carmel/2 SATA disk 2 whole disk + ... + 224 = /dev/carmel/7 SATA disk 7 whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 31. + + 161 char IrCOMM devices (IrDA serial/parallel emulation) + 0 = /dev/ircomm0 First IrCOMM device + 1 = /dev/ircomm1 Second IrCOMM device + ... + 16 = /dev/irlpt0 First IrLPT device + 17 = /dev/irlpt1 Second IrLPT device + ... + + 161 block Carmel 8-port SATA Disks on Second Controller + 0 = /dev/carmel/8 SATA disk 8 whole disk + 1 = /dev/carmel/8p1 SATA disk 8 partition 1 + ... + 31 = /dev/carmel/8p31 SATA disk 8 partition 31 + + 32 = /dev/carmel/9 SATA disk 9 whole disk + 64 = /dev/carmel/10 SATA disk 10 whole disk + ... + 224 = /dev/carmel/15 SATA disk 15 whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 31. + + 162 char Raw block device interface + 0 = /dev/rawctl Raw I/O control device + 1 = /dev/raw/raw1 First raw I/O device + 2 = /dev/raw/raw2 Second raw I/O device + ... + max minor number of raw device is set by kernel config + MAX_RAW_DEVS or raw module parameter 'max_raw_devs' + + 163 char + + 164 char Chase Research AT/PCI-Fast serial card + 0 = /dev/ttyCH0 AT/PCI-Fast board 0, port 0 + ... + 15 = /dev/ttyCH15 AT/PCI-Fast board 0, port 15 + 16 = /dev/ttyCH16 AT/PCI-Fast board 1, port 0 + ... + 31 = /dev/ttyCH31 AT/PCI-Fast board 1, port 15 + 32 = /dev/ttyCH32 AT/PCI-Fast board 2, port 0 + ... + 47 = /dev/ttyCH47 AT/PCI-Fast board 2, port 15 + 48 = /dev/ttyCH48 AT/PCI-Fast board 3, port 0 + ... + 63 = /dev/ttyCH63 AT/PCI-Fast board 3, port 15 + + 165 char Chase Research AT/PCI-Fast serial card - alternate devices + 0 = /dev/cuch0 Callout device for ttyCH0 + ... + 63 = /dev/cuch63 Callout device for ttyCH63 + + 166 char ACM USB modems + 0 = /dev/ttyACM0 First ACM modem + 1 = /dev/ttyACM1 Second ACM modem + ... + + 167 char ACM USB modems - alternate devices + 0 = /dev/cuacm0 Callout device for ttyACM0 + 1 = /dev/cuacm1 Callout device for ttyACM1 + ... + + 168 char Eracom CSA7000 PCI encryption adaptor + 0 = /dev/ecsa0 First CSA7000 + 1 = /dev/ecsa1 Second CSA7000 + ... + + 169 char Eracom CSA8000 PCI encryption adaptor + 0 = /dev/ecsa8-0 First CSA8000 + 1 = /dev/ecsa8-1 Second CSA8000 + ... + + 170 char AMI MegaRAC remote access controller + 0 = /dev/megarac0 First MegaRAC card + 1 = /dev/megarac1 Second MegaRAC card + ... + + 171 char Reserved for IEEE 1394 (Firewire) + + 172 char Moxa Intellio serial card + 0 = /dev/ttyMX0 First Moxa port + 1 = /dev/ttyMX1 Second Moxa port + ... + 127 = /dev/ttyMX127 128th Moxa port + 128 = /dev/moxactl Moxa control port + + 173 char Moxa Intellio serial card - alternate devices + 0 = /dev/cumx0 Callout device for ttyMX0 + 1 = /dev/cumx1 Callout device for ttyMX1 + ... + 127 = /dev/cumx127 Callout device for ttyMX127 + + 174 char SmartIO serial card + 0 = /dev/ttySI0 First SmartIO port + 1 = /dev/ttySI1 Second SmartIO port + ... + + 175 char SmartIO serial card - alternate devices + 0 = /dev/cusi0 Callout device for ttySI0 + 1 = /dev/cusi1 Callout device for ttySI1 + ... + + 176 char nCipher nFast PCI crypto accelerator + 0 = /dev/nfastpci0 First nFast PCI device + 1 = /dev/nfastpci1 First nFast PCI device + ... + + 177 char TI PCILynx memory spaces + 0 = /dev/pcilynx/aux0 AUX space of first PCILynx card + ... + 15 = /dev/pcilynx/aux15 AUX space of 16th PCILynx card + 16 = /dev/pcilynx/rom0 ROM space of first PCILynx card + ... + 31 = /dev/pcilynx/rom15 ROM space of 16th PCILynx card + 32 = /dev/pcilynx/ram0 RAM space of first PCILynx card + ... + 47 = /dev/pcilynx/ram15 RAM space of 16th PCILynx card + + 178 char Giganet cLAN1xxx virtual interface adapter + 0 = /dev/clanvi0 First cLAN adapter + 1 = /dev/clanvi1 Second cLAN adapter + ... + + 179 block MMC block devices + 0 = /dev/mmcblk0 First SD/MMC card + 1 = /dev/mmcblk0p1 First partition on first MMC card + 8 = /dev/mmcblk1 Second SD/MMC card + ... + + The start of next SD/MMC card can be configured with + CONFIG_MMC_BLOCK_MINORS, or overridden at boot/modprobe + time using the mmcblk.perdev_minors option. That would + bump the offset between each card to be the configured + value instead of the default 8. + + 179 char CCube DVXChip-based PCI products + 0 = /dev/dvxirq0 First DVX device + 1 = /dev/dvxirq1 Second DVX device + ... + + 180 char USB devices + 0 = /dev/usb/lp0 First USB printer + ... + 15 = /dev/usb/lp15 16th USB printer + 48 = /dev/usb/scanner0 First USB scanner + ... + 63 = /dev/usb/scanner15 16th USB scanner + 64 = /dev/usb/rio500 Diamond Rio 500 + 65 = /dev/usb/usblcd USBLCD Interface (info@usblcd.de) + 66 = /dev/usb/cpad0 Synaptics cPad (mouse/LCD) + 96 = /dev/usb/hiddev0 1st USB HID device + ... + 111 = /dev/usb/hiddev15 16th USB HID device + 112 = /dev/usb/auer0 1st auerswald ISDN device + ... + 127 = /dev/usb/auer15 16th auerswald ISDN device + 128 = /dev/usb/brlvgr0 First Braille Voyager device + ... + 131 = /dev/usb/brlvgr3 Fourth Braille Voyager device + 132 = /dev/usb/idmouse ID Mouse (fingerprint scanner) device + 133 = /dev/usb/sisusbvga1 First SiSUSB VGA device + ... + 140 = /dev/usb/sisusbvga8 Eighth SISUSB VGA device + 144 = /dev/usb/lcd USB LCD device + 160 = /dev/usb/legousbtower0 1st USB Legotower device + ... + 175 = /dev/usb/legousbtower15 16th USB Legotower device + 176 = /dev/usb/usbtmc1 First USB TMC device + ... + 191 = /dev/usb/usbtmc16 16th USB TMC device + 192 = /dev/usb/yurex1 First USB Yurex device + ... + 209 = /dev/usb/yurex16 16th USB Yurex device + + 180 block USB block devices + 0 = /dev/uba First USB block device + 8 = /dev/ubb Second USB block device + 16 = /dev/ubc Third USB block device + ... + + 181 char Conrad Electronic parallel port radio clocks + 0 = /dev/pcfclock0 First Conrad radio clock + 1 = /dev/pcfclock1 Second Conrad radio clock + ... + + 182 char Picture Elements THR2 binarizer + 0 = /dev/pethr0 First THR2 board + 1 = /dev/pethr1 Second THR2 board + ... + + 183 char SST 5136-DN DeviceNet interface + 0 = /dev/ss5136dn0 First DeviceNet interface + 1 = /dev/ss5136dn1 Second DeviceNet interface + ... + + This device used to be assigned to major number 144. + It had to be moved due to an unfortunate conflict. + + 184 char Picture Elements' video simulator/sender + 0 = /dev/pevss0 First sender board + 1 = /dev/pevss1 Second sender board + ... + + 185 char InterMezzo high availability file system + 0 = /dev/intermezzo0 First cache manager + 1 = /dev/intermezzo1 Second cache manager + ... + + See http://web.archive.org/web/20080115195241/ + http://inter-mezzo.org/index.html + + 186 char Object-based storage control device + 0 = /dev/obd0 First obd control device + 1 = /dev/obd1 Second obd control device + ... + + See ftp://ftp.lustre.org/pub/obd for code and information. + + 187 char DESkey hardware encryption device + 0 = /dev/deskey0 First DES key + 1 = /dev/deskey1 Second DES key + ... + + 188 char USB serial converters + 0 = /dev/ttyUSB0 First USB serial converter + 1 = /dev/ttyUSB1 Second USB serial converter + ... + + 189 char USB serial converters - alternate devices + 0 = /dev/cuusb0 Callout device for ttyUSB0 + 1 = /dev/cuusb1 Callout device for ttyUSB1 + ... + + 190 char Kansas City tracker/tuner card + 0 = /dev/kctt0 First KCT/T card + 1 = /dev/kctt1 Second KCT/T card + ... + + 191 char Reserved for PCMCIA + + 192 char Kernel profiling interface + 0 = /dev/profile Profiling control device + 1 = /dev/profile0 Profiling device for CPU 0 + 2 = /dev/profile1 Profiling device for CPU 1 + ... + + 193 char Kernel event-tracing interface + 0 = /dev/trace Tracing control device + 1 = /dev/trace0 Tracing device for CPU 0 + 2 = /dev/trace1 Tracing device for CPU 1 + ... + + 194 char linVideoStreams (LINVS) + 0 = /dev/mvideo/status0 Video compression status + 1 = /dev/mvideo/stream0 Video stream + 2 = /dev/mvideo/frame0 Single compressed frame + 3 = /dev/mvideo/rawframe0 Raw uncompressed frame + 4 = /dev/mvideo/codec0 Direct codec access + 5 = /dev/mvideo/video4linux0 Video4Linux compatibility + + 16 = /dev/mvideo/status1 Second device + ... + 32 = /dev/mvideo/status2 Third device + ... + ... + 240 = /dev/mvideo/status15 16th device + ... + + 195 char Nvidia graphics devices + 0 = /dev/nvidia0 First Nvidia card + 1 = /dev/nvidia1 Second Nvidia card + ... + 255 = /dev/nvidiactl Nvidia card control device + + 196 char Tormenta T1 card + 0 = /dev/tor/0 Master control channel for all cards + 1 = /dev/tor/1 First DS0 + 2 = /dev/tor/2 Second DS0 + ... + 48 = /dev/tor/48 48th DS0 + 49 = /dev/tor/49 First pseudo-channel + 50 = /dev/tor/50 Second pseudo-channel + ... + + 197 char OpenTNF tracing facility + 0 = /dev/tnf/t0 Trace 0 data extraction + 1 = /dev/tnf/t1 Trace 1 data extraction + ... + 128 = /dev/tnf/status Tracing facility status + 130 = /dev/tnf/trace Tracing device + + 198 char Total Impact TPMP2 quad coprocessor PCI card + 0 = /dev/tpmp2/0 First card + 1 = /dev/tpmp2/1 Second card + ... + + 199 char Veritas volume manager (VxVM) volumes + 0 = /dev/vx/rdsk/*/* First volume + 1 = /dev/vx/rdsk/*/* Second volume + ... + + 199 block Veritas volume manager (VxVM) volumes + 0 = /dev/vx/dsk/*/* First volume + 1 = /dev/vx/dsk/*/* Second volume + ... + + The namespace in these directories is maintained by + the user space VxVM software. + + 200 char Veritas VxVM configuration interface + 0 = /dev/vx/config Configuration access node + 1 = /dev/vx/trace Volume i/o trace access node + 2 = /dev/vx/iod Volume i/o daemon access node + 3 = /dev/vx/info Volume information access node + 4 = /dev/vx/task Volume tasks access node + 5 = /dev/vx/taskmon Volume tasks monitor daemon + + 201 char Veritas VxVM dynamic multipathing driver + 0 = /dev/vx/rdmp/* First multipath device + 1 = /dev/vx/rdmp/* Second multipath device + ... + 201 block Veritas VxVM dynamic multipathing driver + 0 = /dev/vx/dmp/* First multipath device + 1 = /dev/vx/dmp/* Second multipath device + ... + + The namespace in these directories is maintained by + the user space VxVM software. + + 202 char CPU model-specific registers + 0 = /dev/cpu/0/msr MSRs on CPU 0 + 1 = /dev/cpu/1/msr MSRs on CPU 1 + ... + + 202 block Xen Virtual Block Device + 0 = /dev/xvda First Xen VBD whole disk + 16 = /dev/xvdb Second Xen VBD whole disk + 32 = /dev/xvdc Third Xen VBD whole disk + ... + 240 = /dev/xvdp Sixteenth Xen VBD whole disk + + Partitions are handled in the same way as for IDE + disks (see major number 3) except that the limit on + partitions is 15. + + 203 char CPU CPUID information + 0 = /dev/cpu/0/cpuid CPUID on CPU 0 + 1 = /dev/cpu/1/cpuid CPUID on CPU 1 + ... + + 204 char Low-density serial ports + 0 = /dev/ttyLU0 LinkUp Systems L72xx UART - port 0 + 1 = /dev/ttyLU1 LinkUp Systems L72xx UART - port 1 + 2 = /dev/ttyLU2 LinkUp Systems L72xx UART - port 2 + 3 = /dev/ttyLU3 LinkUp Systems L72xx UART - port 3 + 4 = /dev/ttyFB0 Intel Footbridge (ARM) + 5 = /dev/ttySA0 StrongARM builtin serial port 0 + 6 = /dev/ttySA1 StrongARM builtin serial port 1 + 7 = /dev/ttySA2 StrongARM builtin serial port 2 + 8 = /dev/ttySC0 SCI serial port (SuperH) - port 0 + 9 = /dev/ttySC1 SCI serial port (SuperH) - port 1 + 10 = /dev/ttySC2 SCI serial port (SuperH) - port 2 + 11 = /dev/ttySC3 SCI serial port (SuperH) - port 3 + 12 = /dev/ttyFW0 Firmware console - port 0 + 13 = /dev/ttyFW1 Firmware console - port 1 + 14 = /dev/ttyFW2 Firmware console - port 2 + 15 = /dev/ttyFW3 Firmware console - port 3 + 16 = /dev/ttyAM0 ARM "AMBA" serial port 0 + ... + 31 = /dev/ttyAM15 ARM "AMBA" serial port 15 + 32 = /dev/ttyDB0 DataBooster serial port 0 + ... + 39 = /dev/ttyDB7 DataBooster serial port 7 + 40 = /dev/ttySG0 SGI Altix console port + 41 = /dev/ttySMX0 Motorola i.MX - port 0 + 42 = /dev/ttySMX1 Motorola i.MX - port 1 + 43 = /dev/ttySMX2 Motorola i.MX - port 2 + 44 = /dev/ttyMM0 Marvell MPSC - port 0 + 45 = /dev/ttyMM1 Marvell MPSC - port 1 + 46 = /dev/ttyCPM0 PPC CPM (SCC or SMC) - port 0 + ... + 47 = /dev/ttyCPM5 PPC CPM (SCC or SMC) - port 5 + 50 = /dev/ttyIOC0 Altix serial card + ... + 81 = /dev/ttyIOC31 Altix serial card + 82 = /dev/ttyVR0 NEC VR4100 series SIU + 83 = /dev/ttyVR1 NEC VR4100 series DSIU + 84 = /dev/ttyIOC84 Altix ioc4 serial card + ... + 115 = /dev/ttyIOC115 Altix ioc4 serial card + 116 = /dev/ttySIOC0 Altix ioc3 serial card + ... + 147 = /dev/ttySIOC31 Altix ioc3 serial card + 148 = /dev/ttyPSC0 PPC PSC - port 0 + ... + 153 = /dev/ttyPSC5 PPC PSC - port 5 + 154 = /dev/ttyAT0 ATMEL serial port 0 + ... + 169 = /dev/ttyAT15 ATMEL serial port 15 + 170 = /dev/ttyNX0 Hilscher netX serial port 0 + ... + 185 = /dev/ttyNX15 Hilscher netX serial port 15 + 186 = /dev/ttyJ0 JTAG1 DCC protocol based serial port emulation + 187 = /dev/ttyUL0 Xilinx uartlite - port 0 + ... + 190 = /dev/ttyUL3 Xilinx uartlite - port 3 + 191 = /dev/xvc0 Xen virtual console - port 0 + 192 = /dev/ttyPZ0 pmac_zilog - port 0 + ... + 195 = /dev/ttyPZ3 pmac_zilog - port 3 + 196 = /dev/ttyTX0 TX39/49 serial port 0 + ... + 204 = /dev/ttyTX7 TX39/49 serial port 7 + 205 = /dev/ttySC0 SC26xx serial port 0 + 206 = /dev/ttySC1 SC26xx serial port 1 + 207 = /dev/ttySC2 SC26xx serial port 2 + 208 = /dev/ttySC3 SC26xx serial port 3 + 209 = /dev/ttyMAX0 MAX3100 serial port 0 + 210 = /dev/ttyMAX1 MAX3100 serial port 1 + 211 = /dev/ttyMAX2 MAX3100 serial port 2 + 212 = /dev/ttyMAX3 MAX3100 serial port 3 + + 205 char Low-density serial ports (alternate device) + 0 = /dev/culu0 Callout device for ttyLU0 + 1 = /dev/culu1 Callout device for ttyLU1 + 2 = /dev/culu2 Callout device for ttyLU2 + 3 = /dev/culu3 Callout device for ttyLU3 + 4 = /dev/cufb0 Callout device for ttyFB0 + 5 = /dev/cusa0 Callout device for ttySA0 + 6 = /dev/cusa1 Callout device for ttySA1 + 7 = /dev/cusa2 Callout device for ttySA2 + 8 = /dev/cusc0 Callout device for ttySC0 + 9 = /dev/cusc1 Callout device for ttySC1 + 10 = /dev/cusc2 Callout device for ttySC2 + 11 = /dev/cusc3 Callout device for ttySC3 + 12 = /dev/cufw0 Callout device for ttyFW0 + 13 = /dev/cufw1 Callout device for ttyFW1 + 14 = /dev/cufw2 Callout device for ttyFW2 + 15 = /dev/cufw3 Callout device for ttyFW3 + 16 = /dev/cuam0 Callout device for ttyAM0 + ... + 31 = /dev/cuam15 Callout device for ttyAM15 + 32 = /dev/cudb0 Callout device for ttyDB0 + ... + 39 = /dev/cudb7 Callout device for ttyDB7 + 40 = /dev/cusg0 Callout device for ttySG0 + 41 = /dev/ttycusmx0 Callout device for ttySMX0 + 42 = /dev/ttycusmx1 Callout device for ttySMX1 + 43 = /dev/ttycusmx2 Callout device for ttySMX2 + 46 = /dev/cucpm0 Callout device for ttyCPM0 + ... + 49 = /dev/cucpm5 Callout device for ttyCPM5 + 50 = /dev/cuioc40 Callout device for ttyIOC40 + ... + 81 = /dev/cuioc431 Callout device for ttyIOC431 + 82 = /dev/cuvr0 Callout device for ttyVR0 + 83 = /dev/cuvr1 Callout device for ttyVR1 + + 206 char OnStream SC-x0 tape devices + 0 = /dev/osst0 First OnStream SCSI tape, mode 0 + 1 = /dev/osst1 Second OnStream SCSI tape, mode 0 + ... + 32 = /dev/osst0l First OnStream SCSI tape, mode 1 + 33 = /dev/osst1l Second OnStream SCSI tape, mode 1 + ... + 64 = /dev/osst0m First OnStream SCSI tape, mode 2 + 65 = /dev/osst1m Second OnStream SCSI tape, mode 2 + ... + 96 = /dev/osst0a First OnStream SCSI tape, mode 3 + 97 = /dev/osst1a Second OnStream SCSI tape, mode 3 + ... + 128 = /dev/nosst0 No rewind version of /dev/osst0 + 129 = /dev/nosst1 No rewind version of /dev/osst1 + ... + 160 = /dev/nosst0l No rewind version of /dev/osst0l + 161 = /dev/nosst1l No rewind version of /dev/osst1l + ... + 192 = /dev/nosst0m No rewind version of /dev/osst0m + 193 = /dev/nosst1m No rewind version of /dev/osst1m + ... + 224 = /dev/nosst0a No rewind version of /dev/osst0a + 225 = /dev/nosst1a No rewind version of /dev/osst1a + ... + + The OnStream SC-x0 SCSI tapes do not support the + standard SCSI SASD command set and therefore need + their own driver "osst". Note that the IDE, USB (and + maybe ParPort) versions may be driven via ide-scsi or + usb-storage SCSI emulation and this osst device and + driver as well. The ADR-x0 drives are QIC-157 + compliant and don't need osst. + + 207 char Compaq ProLiant health feature indicate + 0 = /dev/cpqhealth/cpqw Redirector interface + 1 = /dev/cpqhealth/crom EISA CROM + 2 = /dev/cpqhealth/cdt Data Table + 3 = /dev/cpqhealth/cevt Event Log + 4 = /dev/cpqhealth/casr Automatic Server Recovery + 5 = /dev/cpqhealth/cecc ECC Memory + 6 = /dev/cpqhealth/cmca Machine Check Architecture + 7 = /dev/cpqhealth/ccsm Deprecated CDT + 8 = /dev/cpqhealth/cnmi NMI Handling + 9 = /dev/cpqhealth/css Sideshow Management + 10 = /dev/cpqhealth/cram CMOS interface + 11 = /dev/cpqhealth/cpci PCI IRQ interface + + 208 char User space serial ports + 0 = /dev/ttyU0 First user space serial port + 1 = /dev/ttyU1 Second user space serial port + ... + + 209 char User space serial ports (alternate devices) + 0 = /dev/cuu0 Callout device for ttyU0 + 1 = /dev/cuu1 Callout device for ttyU1 + ... + + 210 char SBE, Inc. sync/async serial card + 0 = /dev/sbei/wxcfg0 Configuration device for board 0 + 1 = /dev/sbei/dld0 Download device for board 0 + 2 = /dev/sbei/wan00 WAN device, port 0, board 0 + 3 = /dev/sbei/wan01 WAN device, port 1, board 0 + 4 = /dev/sbei/wan02 WAN device, port 2, board 0 + 5 = /dev/sbei/wan03 WAN device, port 3, board 0 + 6 = /dev/sbei/wanc00 WAN clone device, port 0, board 0 + 7 = /dev/sbei/wanc01 WAN clone device, port 1, board 0 + 8 = /dev/sbei/wanc02 WAN clone device, port 2, board 0 + 9 = /dev/sbei/wanc03 WAN clone device, port 3, board 0 + 10 = /dev/sbei/wxcfg1 Configuration device for board 1 + 11 = /dev/sbei/dld1 Download device for board 1 + 12 = /dev/sbei/wan10 WAN device, port 0, board 1 + 13 = /dev/sbei/wan11 WAN device, port 1, board 1 + 14 = /dev/sbei/wan12 WAN device, port 2, board 1 + 15 = /dev/sbei/wan13 WAN device, port 3, board 1 + 16 = /dev/sbei/wanc10 WAN clone device, port 0, board 1 + 17 = /dev/sbei/wanc11 WAN clone device, port 1, board 1 + 18 = /dev/sbei/wanc12 WAN clone device, port 2, board 1 + 19 = /dev/sbei/wanc13 WAN clone device, port 3, board 1 + ... + + Yes, each board is really spaced 10 (decimal) apart. + + 211 char Addinum CPCI1500 digital I/O card + 0 = /dev/addinum/cpci1500/0 First CPCI1500 card + 1 = /dev/addinum/cpci1500/1 Second CPCI1500 card + ... + + 212 char LinuxTV.org DVB driver subsystem + 0 = /dev/dvb/adapter0/video0 first video decoder of first card + 1 = /dev/dvb/adapter0/audio0 first audio decoder of first card + 2 = /dev/dvb/adapter0/sec0 (obsolete/unused) + 3 = /dev/dvb/adapter0/frontend0 first frontend device of first card + 4 = /dev/dvb/adapter0/demux0 first demux device of first card + 5 = /dev/dvb/adapter0/dvr0 first digital video recoder device of first card + 6 = /dev/dvb/adapter0/ca0 first common access port of first card + 7 = /dev/dvb/adapter0/net0 first network device of first card + 8 = /dev/dvb/adapter0/osd0 first on-screen-display device of first card + 9 = /dev/dvb/adapter0/video1 second video decoder of first card + ... + 64 = /dev/dvb/adapter1/video0 first video decoder of second card + ... + 128 = /dev/dvb/adapter2/video0 first video decoder of third card + ... + 196 = /dev/dvb/adapter3/video0 first video decoder of fourth card + + 216 char Bluetooth RFCOMM TTY devices + 0 = /dev/rfcomm0 First Bluetooth RFCOMM TTY device + 1 = /dev/rfcomm1 Second Bluetooth RFCOMM TTY device + ... + + 217 char Bluetooth RFCOMM TTY devices (alternate devices) + 0 = /dev/curf0 Callout device for rfcomm0 + 1 = /dev/curf1 Callout device for rfcomm1 + ... + + 218 char The Logical Company bus Unibus/Qbus adapters + 0 = /dev/logicalco/bci/0 First bus adapter + 1 = /dev/logicalco/bci/1 First bus adapter + ... + + 219 char The Logical Company DCI-1300 digital I/O card + 0 = /dev/logicalco/dci1300/0 First DCI-1300 card + 1 = /dev/logicalco/dci1300/1 Second DCI-1300 card + ... + + 220 char Myricom Myrinet "GM" board + 0 = /dev/myricom/gm0 First Myrinet GM board + 1 = /dev/myricom/gmp0 First board "root access" + 2 = /dev/myricom/gm1 Second Myrinet GM board + 3 = /dev/myricom/gmp1 Second board "root access" + ... + + 221 char VME bus + 0 = /dev/bus/vme/m0 First master image + 1 = /dev/bus/vme/m1 Second master image + 2 = /dev/bus/vme/m2 Third master image + 3 = /dev/bus/vme/m3 Fourth master image + 4 = /dev/bus/vme/s0 First slave image + 5 = /dev/bus/vme/s1 Second slave image + 6 = /dev/bus/vme/s2 Third slave image + 7 = /dev/bus/vme/s3 Fourth slave image + 8 = /dev/bus/vme/ctl Control + + It is expected that all VME bus drivers will use the + same interface. For interface documentation see + http://www.vmelinux.org/. + + 224 char A2232 serial card + 0 = /dev/ttyY0 First A2232 port + 1 = /dev/ttyY1 Second A2232 port + ... + + 225 char A2232 serial card (alternate devices) + 0 = /dev/cuy0 Callout device for ttyY0 + 1 = /dev/cuy1 Callout device for ttyY1 + ... + + 226 char Direct Rendering Infrastructure (DRI) + 0 = /dev/dri/card0 First graphics card + 1 = /dev/dri/card1 Second graphics card + ... + + 227 char IBM 3270 terminal Unix tty access + 1 = /dev/3270/tty1 First 3270 terminal + 2 = /dev/3270/tty2 Seconds 3270 terminal + ... + + 228 char IBM 3270 terminal block-mode access + 0 = /dev/3270/tub Controlling interface + 1 = /dev/3270/tub1 First 3270 terminal + 2 = /dev/3270/tub2 Second 3270 terminal + ... + + 229 char IBM iSeries/pSeries virtual console + 0 = /dev/hvc0 First console port + 1 = /dev/hvc1 Second console port + ... + + 230 char IBM iSeries virtual tape + 0 = /dev/iseries/vt0 First virtual tape, mode 0 + 1 = /dev/iseries/vt1 Second virtual tape, mode 0 + ... + 32 = /dev/iseries/vt0l First virtual tape, mode 1 + 33 = /dev/iseries/vt1l Second virtual tape, mode 1 + ... + 64 = /dev/iseries/vt0m First virtual tape, mode 2 + 65 = /dev/iseries/vt1m Second virtual tape, mode 2 + ... + 96 = /dev/iseries/vt0a First virtual tape, mode 3 + 97 = /dev/iseries/vt1a Second virtual tape, mode 3 + ... + 128 = /dev/iseries/nvt0 First virtual tape, mode 0, no rewind + 129 = /dev/iseries/nvt1 Second virtual tape, mode 0, no rewind + ... + 160 = /dev/iseries/nvt0l First virtual tape, mode 1, no rewind + 161 = /dev/iseries/nvt1l Second virtual tape, mode 1, no rewind + ... + 192 = /dev/iseries/nvt0m First virtual tape, mode 2, no rewind + 193 = /dev/iseries/nvt1m Second virtual tape, mode 2, no rewind + ... + 224 = /dev/iseries/nvt0a First virtual tape, mode 3, no rewind + 225 = /dev/iseries/nvt1a Second virtual tape, mode 3, no rewind + ... + + "No rewind" refers to the omission of the default + automatic rewind on device close. The MTREW or MTOFFL + ioctl()'s can be used to rewind the tape regardless of + the device used to access it. + + 231 char InfiniBand + 0 = /dev/infiniband/umad0 + 1 = /dev/infiniband/umad1 + ... + 63 = /dev/infiniband/umad63 63rd InfiniBandMad device + 64 = /dev/infiniband/issm0 First InfiniBand IsSM device + 65 = /dev/infiniband/issm1 Second InfiniBand IsSM device + ... + 127 = /dev/infiniband/issm63 63rd InfiniBand IsSM device + 128 = /dev/infiniband/uverbs0 First InfiniBand verbs device + 129 = /dev/infiniband/uverbs1 Second InfiniBand verbs device + ... + 159 = /dev/infiniband/uverbs31 31st InfiniBand verbs device + + 232 char Biometric Devices + 0 = /dev/biometric/sensor0/fingerprint first fingerprint sensor on first device + 1 = /dev/biometric/sensor0/iris first iris sensor on first device + 2 = /dev/biometric/sensor0/retina first retina sensor on first device + 3 = /dev/biometric/sensor0/voiceprint first voiceprint sensor on first device + 4 = /dev/biometric/sensor0/facial first facial sensor on first device + 5 = /dev/biometric/sensor0/hand first hand sensor on first device + ... + 10 = /dev/biometric/sensor1/fingerprint first fingerprint sensor on second device + ... + 20 = /dev/biometric/sensor2/fingerprint first fingerprint sensor on third device + ... + + 233 char PathScale InfiniPath interconnect + 0 = /dev/ipath Primary device for programs (any unit) + 1 = /dev/ipath0 Access specifically to unit 0 + 2 = /dev/ipath1 Access specifically to unit 1 + ... + 4 = /dev/ipath3 Access specifically to unit 3 + 129 = /dev/ipath_sma Device used by Subnet Management Agent + 130 = /dev/ipath_diag Device used by diagnostics programs + + 234-254 char RESERVED FOR DYNAMIC ASSIGNMENT + Character devices that request a dynamic allocation of major number will + take numbers starting from 254 and downward. + + 240-254 block LOCAL/EXPERIMENTAL USE + Allocated for local/experimental use. For devices not + assigned official numbers, these ranges should be + used in order to avoid conflicting with future assignments. + + 255 char RESERVED + + 255 block RESERVED + + This major is reserved to assist the expansion to a + larger number space. No device nodes with this major + should ever be created on the filesystem. + (This is probably not true anymore, but I'll leave it + for now /Torben) + + ---LARGE MAJORS!!!!!--- + + 256 char Equinox SST multi-port serial boards + 0 = /dev/ttyEQ0 First serial port on first Equinox SST board + 127 = /dev/ttyEQ127 Last serial port on first Equinox SST board + 128 = /dev/ttyEQ128 First serial port on second Equinox SST board + ... + 1027 = /dev/ttyEQ1027 Last serial port on eighth Equinox SST board + + 256 block Resident Flash Disk Flash Translation Layer + 0 = /dev/rfda First RFD FTL layer + 16 = /dev/rfdb Second RFD FTL layer + ... + 240 = /dev/rfdp 16th RFD FTL layer + + 257 char Phoenix Technologies Cryptographic Services Driver + 0 = /dev/ptlsec Crypto Services Driver + + 257 block SSFDC Flash Translation Layer filesystem + 0 = /dev/ssfdca First SSFDC layer + 8 = /dev/ssfdcb Second SSFDC layer + 16 = /dev/ssfdcc Third SSFDC layer + 24 = /dev/ssfdcd 4th SSFDC layer + 32 = /dev/ssfdce 5th SSFDC layer + 40 = /dev/ssfdcf 6th SSFDC layer + 48 = /dev/ssfdcg 7th SSFDC layer + 56 = /dev/ssfdch 8th SSFDC layer + + 258 block ROM/Flash read-only translation layer + 0 = /dev/blockrom0 First ROM card's translation layer interface + 1 = /dev/blockrom1 Second ROM card's translation layer interface + ... + + 259 block Block Extended Major + Used dynamically to hold additional partition minor + numbers and allow large numbers of partitions per device + + 259 char FPGA configuration interfaces + 0 = /dev/icap0 First Xilinx internal configuration + 1 = /dev/icap1 Second Xilinx internal configuration + + 260 char OSD (Object-based-device) SCSI Device + 0 = /dev/osd0 First OSD Device + 1 = /dev/osd1 Second OSD Device + ... + 255 = /dev/osd255 256th OSD Device diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst new file mode 100644 index 000000000000..88adcfdf5b2b --- /dev/null +++ b/Documentation/admin-guide/dynamic-debug-howto.rst @@ -0,0 +1,353 @@ +Dynamic debug ++++++++++++++ + + +Introduction +============ + +This document describes how to use the dynamic debug (dyndbg) feature. + +Dynamic debug is designed to allow you to dynamically enable/disable +kernel code to obtain additional kernel information. Currently, if +``CONFIG_DYNAMIC_DEBUG`` is set, then all ``pr_debug()``/``dev_dbg()`` and +``print_hex_dump_debug()``/``print_hex_dump_bytes()`` calls can be dynamically +enabled per-callsite. + +If ``CONFIG_DYNAMIC_DEBUG`` is not set, ``print_hex_dump_debug()`` is just +shortcut for ``print_hex_dump(KERN_DEBUG)``. + +For ``print_hex_dump_debug()``/``print_hex_dump_bytes()``, format string is +its ``prefix_str`` argument, if it is constant string; or ``hexdump`` +in case ``prefix_str`` is build dynamically. + +Dynamic debug has even more useful features: + + * Simple query language allows turning on and off debugging + statements by matching any combination of 0 or 1 of: + + - source filename + - function name + - line number (including ranges of line numbers) + - module name + - format string + + * Provides a debugfs control file: ``<debugfs>/dynamic_debug/control`` + which can be read to display the complete list of known debug + statements, to help guide you + +Controlling dynamic debug Behaviour +=================================== + +The behaviour of ``pr_debug()``/``dev_dbg()`` are controlled via writing to a +control file in the 'debugfs' filesystem. Thus, you must first mount +the debugfs filesystem, in order to make use of this feature. +Subsequently, we refer to the control file as: +``<debugfs>/dynamic_debug/control``. For example, if you want to enable +printing from source file ``svcsock.c``, line 1603 you simply do:: + + nullarbor:~ # echo 'file svcsock.c line 1603 +p' > + <debugfs>/dynamic_debug/control + +If you make a mistake with the syntax, the write will fail thus:: + + nullarbor:~ # echo 'file svcsock.c wtf 1 +p' > + <debugfs>/dynamic_debug/control + -bash: echo: write error: Invalid argument + +Viewing Dynamic Debug Behaviour +=============================== + +You can view the currently configured behaviour of all the debug +statements via:: + + nullarbor:~ # cat <debugfs>/dynamic_debug/control + # filename:lineno [module]function flags format + /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:323 [svcxprt_rdma]svc_rdma_cleanup =_ "SVCRDMA Module Removed, deregister RPC RDMA transport\012" + /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:341 [svcxprt_rdma]svc_rdma_init =_ "\011max_inline : %d\012" + /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:340 [svcxprt_rdma]svc_rdma_init =_ "\011sq_depth : %d\012" + /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:338 [svcxprt_rdma]svc_rdma_init =_ "\011max_requests : %d\012" + ... + + +You can also apply standard Unix text manipulation filters to this +data, e.g.:: + + nullarbor:~ # grep -i rdma <debugfs>/dynamic_debug/control | wc -l + 62 + + nullarbor:~ # grep -i tcp <debugfs>/dynamic_debug/control | wc -l + 42 + +The third column shows the currently enabled flags for each debug +statement callsite (see below for definitions of the flags). The +default value, with no flags enabled, is ``=_``. So you can view all +the debug statement callsites with any non-default flags:: + + nullarbor:~ # awk '$3 != "=_"' <debugfs>/dynamic_debug/control + # filename:lineno [module]function flags format + /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svcsock.c:1603 [sunrpc]svc_send p "svc_process: st_sendto returned %d\012" + +Command Language Reference +========================== + +At the lexical level, a command comprises a sequence of words separated +by spaces or tabs. So these are all equivalent:: + + nullarbor:~ # echo -c 'file svcsock.c line 1603 +p' > + <debugfs>/dynamic_debug/control + nullarbor:~ # echo -c ' file svcsock.c line 1603 +p ' > + <debugfs>/dynamic_debug/control + nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > + <debugfs>/dynamic_debug/control + +Command submissions are bounded by a write() system call. +Multiple commands can be written together, separated by ``;`` or ``\n``:: + + ~# echo "func pnpacpi_get_resources +p; func pnp_assign_mem +p" \ + > <debugfs>/dynamic_debug/control + +If your query set is big, you can batch them too:: + + ~# cat query-batch-file > <debugfs>/dynamic_debug/control + +A another way is to use wildcard. The match rule support ``*`` (matches +zero or more characters) and ``?`` (matches exactly one character).For +example, you can match all usb drivers:: + + ~# echo "file drivers/usb/* +p" > <debugfs>/dynamic_debug/control + +At the syntactical level, a command comprises a sequence of match +specifications, followed by a flags change specification:: + + command ::= match-spec* flags-spec + +The match-spec's are used to choose a subset of the known pr_debug() +callsites to which to apply the flags-spec. Think of them as a query +with implicit ANDs between each pair. Note that an empty list of +match-specs will select all debug statement callsites. + +A match specification comprises a keyword, which controls the +attribute of the callsite to be compared, and a value to compare +against. Possible keywords are::: + + match-spec ::= 'func' string | + 'file' string | + 'module' string | + 'format' string | + 'line' line-range + + line-range ::= lineno | + '-'lineno | + lineno'-' | + lineno'-'lineno + + lineno ::= unsigned-int + +.. note:: + + ``line-range`` cannot contain space, e.g. + "1-30" is valid range but "1 - 30" is not. + + +The meanings of each keyword are: + +func + The given string is compared against the function name + of each callsite. Example:: + + func svc_tcp_accept + +file + The given string is compared against either the full pathname, the + src-root relative pathname, or the basename of the source file of + each callsite. Examples:: + + file svcsock.c + file kernel/freezer.c + file /usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svcsock.c + +module + The given string is compared against the module name + of each callsite. The module name is the string as + seen in ``lsmod``, i.e. without the directory or the ``.ko`` + suffix and with ``-`` changed to ``_``. Examples:: + + module sunrpc + module nfsd + +format + The given string is searched for in the dynamic debug format + string. Note that the string does not need to match the + entire format, only some part. Whitespace and other + special characters can be escaped using C octal character + escape ``\ooo`` notation, e.g. the space character is ``\040``. + Alternatively, the string can be enclosed in double quote + characters (``"``) or single quote characters (``'``). + Examples:: + + format svcrdma: // many of the NFS/RDMA server pr_debugs + format readahead // some pr_debugs in the readahead cache + format nfsd:\040SETATTR // one way to match a format with whitespace + format "nfsd: SETATTR" // a neater way to match a format with whitespace + format 'nfsd: SETATTR' // yet another way to match a format with whitespace + +line + The given line number or range of line numbers is compared + against the line number of each ``pr_debug()`` callsite. A single + line number matches the callsite line number exactly. A + range of line numbers matches any callsite between the first + and last line number inclusive. An empty first number means + the first line in the file, an empty line number means the + last number in the file. Examples:: + + line 1603 // exactly line 1603 + line 1600-1605 // the six lines from line 1600 to line 1605 + line -1605 // the 1605 lines from line 1 to line 1605 + line 1600- // all lines from line 1600 to the end of the file + +The flags specification comprises a change operation followed +by one or more flag characters. The change operation is one +of the characters:: + + - remove the given flags + + add the given flags + = set the flags to the given flags + +The flags are:: + + p enables the pr_debug() callsite. + f Include the function name in the printed message + l Include line number in the printed message + m Include module name in the printed message + t Include thread ID in messages not generated from interrupt context + _ No flags are set. (Or'd with others on input) + +For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only ``p`` flag +have meaning, other flags ignored. + +For display, the flags are preceded by ``=`` +(mnemonic: what the flags are currently equal to). + +Note the regexp ``^[-+=][flmpt_]+$`` matches a flags specification. +To clear all flags at once, use ``=_`` or ``-flmpt``. + + +Debug messages during Boot Process +================================== + +To activate debug messages for core code and built-in modules during +the boot process, even before userspace and debugfs exists, use +``dyndbg="QUERY"``, ``module.dyndbg="QUERY"``, or ``ddebug_query="QUERY"`` +(``ddebug_query`` is obsoleted by ``dyndbg``, and deprecated). QUERY follows +the syntax described above, but must not exceed 1023 characters. Your +bootloader may impose lower limits. + +These ``dyndbg`` params are processed just after the ddebug tables are +processed, as part of the arch_initcall. Thus you can enable debug +messages in all code run after this arch_initcall via this boot +parameter. + +On an x86 system for example ACPI enablement is a subsys_initcall and:: + + dyndbg="file ec.c +p" + +will show early Embedded Controller transactions during ACPI setup if +your machine (typically a laptop) has an Embedded Controller. +PCI (or other devices) initialization also is a hot candidate for using +this boot parameter for debugging purposes. + +If ``foo`` module is not built-in, ``foo.dyndbg`` will still be processed at +boot time, without effect, but will be reprocessed when module is +loaded later. ``dyndbg_query=`` and bare ``dyndbg=`` are only processed at +boot. + + +Debug Messages at Module Initialization Time +============================================ + +When ``modprobe foo`` is called, modprobe scans ``/proc/cmdline`` for +``foo.params``, strips ``foo.``, and passes them to the kernel along with +params given in modprobe args or ``/etc/modprob.d/*.conf`` files, +in the following order: + +1. parameters given via ``/etc/modprobe.d/*.conf``:: + + options foo dyndbg=+pt + options foo dyndbg # defaults to +p + +2. ``foo.dyndbg`` as given in boot args, ``foo.`` is stripped and passed:: + + foo.dyndbg=" func bar +p; func buz +mp" + +3. args to modprobe:: + + modprobe foo dyndbg==pmf # override previous settings + +These ``dyndbg`` queries are applied in order, with last having final say. +This allows boot args to override or modify those from ``/etc/modprobe.d`` +(sensible, since 1 is system wide, 2 is kernel or boot specific), and +modprobe args to override both. + +In the ``foo.dyndbg="QUERY"`` form, the query must exclude ``module foo``. +``foo`` is extracted from the param-name, and applied to each query in +``QUERY``, and only 1 match-spec of each type is allowed. + +The ``dyndbg`` option is a "fake" module parameter, which means: + +- modules do not need to define it explicitly +- every module gets it tacitly, whether they use pr_debug or not +- it doesn't appear in ``/sys/module/$module/parameters/`` + To see it, grep the control file, or inspect ``/proc/cmdline.`` + +For ``CONFIG_DYNAMIC_DEBUG`` kernels, any settings given at boot-time (or +enabled by ``-DDEBUG`` flag during compilation) can be disabled later via +the sysfs interface if the debug messages are no longer needed:: + + echo "module module_name -p" > <debugfs>/dynamic_debug/control + +Examples +======== + +:: + + // enable the message at line 1603 of file svcsock.c + nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' > + <debugfs>/dynamic_debug/control + + // enable all the messages in file svcsock.c + nullarbor:~ # echo -n 'file svcsock.c +p' > + <debugfs>/dynamic_debug/control + + // enable all the messages in the NFS server module + nullarbor:~ # echo -n 'module nfsd +p' > + <debugfs>/dynamic_debug/control + + // enable all 12 messages in the function svc_process() + nullarbor:~ # echo -n 'func svc_process +p' > + <debugfs>/dynamic_debug/control + + // disable all 12 messages in the function svc_process() + nullarbor:~ # echo -n 'func svc_process -p' > + <debugfs>/dynamic_debug/control + + // enable messages for NFS calls READ, READLINK, READDIR and READDIR+. + nullarbor:~ # echo -n 'format "nfsd: READ" +p' > + <debugfs>/dynamic_debug/control + + // enable messages in files of which the paths include string "usb" + nullarbor:~ # echo -n '*usb* +p' > <debugfs>/dynamic_debug/control + + // enable all messages + nullarbor:~ # echo -n '+p' > <debugfs>/dynamic_debug/control + + // add module, function to all enabled messages + nullarbor:~ # echo -n '+mf' > <debugfs>/dynamic_debug/control + + // boot-args example, with newlines and comments for readability + Kernel command line: ... + // see whats going on in dyndbg=value processing + dynamic_debug.verbose=1 + // enable pr_debugs in 2 builtins, #cmt is stripped + dyndbg="module params +p #cmt ; module sys +p" + // enable pr_debugs in 2 functions in a module loaded later + pc87360.dyndbg="func pc87360_init_device +p; func pc87360_find +p" diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst new file mode 100644 index 000000000000..8ddae4e4299a --- /dev/null +++ b/Documentation/admin-guide/index.rst @@ -0,0 +1,69 @@ +The Linux kernel user's and administrator's guide +================================================= + +The following is a collection of user-oriented documents that have been +added to the kernel over time. There is, as yet, little overall order or +organization here — this material was not written to be a single, coherent +document! With luck things will improve quickly over time. + +This initial section contains overall information, including the README +file describing the kernel as a whole, documentation on kernel parameters, +etc. + +.. toctree:: + :maxdepth: 1 + + README + kernel-parameters + devices + +Here is a set of documents aimed at users who are trying to track down +problems and bugs in particular. + +.. toctree:: + :maxdepth: 1 + + reporting-bugs + security-bugs + bug-hunting + bug-bisect + tainted-kernels + ramoops + dynamic-debug-howto + init + +This is the beginning of a section with information of interest to +application developers. Documents covering various aspects of the kernel +ABI will be found here. + +.. toctree:: + :maxdepth: 1 + + sysfs-rules + +The rest of this manual consists of various unordered guides on how to +configure specific aspects of kernel behavior to your liking. + +.. toctree:: + :maxdepth: 1 + + initrd + serial-console + braille-console + parport + md + module-signing + sysrq + unicode + vga-softcursor + binfmt-misc + mono + java + ras + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/admin-guide/init.rst b/Documentation/admin-guide/init.rst new file mode 100644 index 000000000000..e89d97f31eaf --- /dev/null +++ b/Documentation/admin-guide/init.rst @@ -0,0 +1,52 @@ +Explaining the dreaded "No init found." boot hang message +========================================================= + +OK, so you've got this pretty unintuitive message (currently located +in init/main.c) and are wondering what the H*** went wrong. +Some high-level reasons for failure (listed roughly in order of execution) +to load the init binary are: + +A) Unable to mount root FS +B) init binary doesn't exist on rootfs +C) broken console device +D) binary exists but dependencies not available +E) binary cannot be loaded + +Detailed explanations: + +A) Set "debug" kernel parameter (in bootloader config file or CONFIG_CMDLINE) + to get more detailed kernel messages. +B) make sure you have the correct root FS type + (and ``root=`` kernel parameter points to the correct partition), + required drivers such as storage hardware (such as SCSI or USB!) + and filesystem (ext3, jffs2 etc.) are builtin (alternatively as modules, + to be pre-loaded by an initrd) +C) Possibly a conflict in ``console= setup`` --> initial console unavailable. + E.g. some serial consoles are unreliable due to serial IRQ issues (e.g. + missing interrupt-based configuration). + Try using a different ``console= device`` or e.g. ``netconsole=``. +D) e.g. required library dependencies of the init binary such as + ``/lib/ld-linux.so.2`` missing or broken. Use + ``readelf -d <INIT>|grep NEEDED`` to find out which libraries are required. +E) make sure the binary's architecture matches your hardware. + E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM hardware. + In case you tried loading a non-binary file here (shell script?), + you should make sure that the script specifies an interpreter in its shebang + header line (``#!/...``) that is fully working (including its library + dependencies). And before tackling scripts, better first test a simple + non-script binary such as ``/bin/sh`` and confirm its successful execution. + To find out more, add code ``to init/main.c`` to display kernel_execve()s + return values. + +Please extend this explanation whenever you find new failure causes +(after all loading the init binary is a CRITICAL and hard transition step +which needs to be made as painless as possible), then submit patch to LKML. +Further TODOs: + +- Implement the various ``run_init_process()`` invocations via a struct array + which can then store the ``kernel_execve()`` result value and on failure + log it all by iterating over **all** results (very important usability fix). +- try to make the implementation itself more helpful in general, + e.g. by providing additional error messages at affected places. + +Andreas Mohr <andi at lisas period de> diff --git a/Documentation/admin-guide/initrd.rst b/Documentation/admin-guide/initrd.rst new file mode 100644 index 000000000000..a03dabaaf3a3 --- /dev/null +++ b/Documentation/admin-guide/initrd.rst @@ -0,0 +1,383 @@ +Using the initial RAM disk (initrd) +=================================== + +Written 1996,2000 by Werner Almesberger <werner.almesberger@epfl.ch> and +Hans Lermen <lermen@fgan.de> + + +initrd provides the capability to load a RAM disk by the boot loader. +This RAM disk can then be mounted as the root file system and programs +can be run from it. Afterwards, a new root file system can be mounted +from a different device. The previous root (from initrd) is then moved +to a directory and can be subsequently unmounted. + +initrd is mainly designed to allow system startup to occur in two phases, +where the kernel comes up with a minimum set of compiled-in drivers, and +where additional modules are loaded from initrd. + +This document gives a brief overview of the use of initrd. A more detailed +discussion of the boot process can be found in [#f1]_. + + +Operation +--------- + +When using initrd, the system typically boots as follows: + + 1) the boot loader loads the kernel and the initial RAM disk + 2) the kernel converts initrd into a "normal" RAM disk and + frees the memory used by initrd + 3) if the root device is not ``/dev/ram0``, the old (deprecated) + change_root procedure is followed. see the "Obsolete root change + mechanism" section below. + 4) root device is mounted. if it is ``/dev/ram0``, the initrd image is + then mounted as root + 5) /sbin/init is executed (this can be any valid executable, including + shell scripts; it is run with uid 0 and can do basically everything + init can do). + 6) init mounts the "real" root file system + 7) init places the root file system at the root directory using the + pivot_root system call + 8) init execs the ``/sbin/init`` on the new root filesystem, performing + the usual boot sequence + 9) the initrd file system is removed + +Note that changing the root directory does not involve unmounting it. +It is therefore possible to leave processes running on initrd during that +procedure. Also note that file systems mounted under initrd continue to +be accessible. + + +Boot command-line options +------------------------- + +initrd adds the following new options:: + + initrd=<path> (e.g. LOADLIN) + + Loads the specified file as the initial RAM disk. When using LILO, you + have to specify the RAM disk image file in /etc/lilo.conf, using the + INITRD configuration variable. + + noinitrd + + initrd data is preserved but it is not converted to a RAM disk and + the "normal" root file system is mounted. initrd data can be read + from /dev/initrd. Note that the data in initrd can have any structure + in this case and doesn't necessarily have to be a file system image. + This option is used mainly for debugging. + + Note: /dev/initrd is read-only and it can only be used once. As soon + as the last process has closed it, all data is freed and /dev/initrd + can't be opened anymore. + + root=/dev/ram0 + + initrd is mounted as root, and the normal boot procedure is followed, + with the RAM disk mounted as root. + +Compressed cpio images +---------------------- + +Recent kernels have support for populating a ramdisk from a compressed cpio +archive. On such systems, the creation of a ramdisk image doesn't need to +involve special block devices or loopbacks; you merely create a directory on +disk with the desired initrd content, cd to that directory, and run (as an +example):: + + find . | cpio --quiet -H newc -o | gzip -9 -n > /boot/imagefile.img + +Examining the contents of an existing image file is just as simple:: + + mkdir /tmp/imagefile + cd /tmp/imagefile + gzip -cd /boot/imagefile.img | cpio -imd --quiet + +Installation +------------ + +First, a directory for the initrd file system has to be created on the +"normal" root file system, e.g.:: + + # mkdir /initrd + +The name is not relevant. More details can be found on the +:manpage:`pivot_root(2)` man page. + +If the root file system is created during the boot procedure (i.e. if +you're building an install floppy), the root file system creation +procedure should create the ``/initrd`` directory. + +If initrd will not be mounted in some cases, its content is still +accessible if the following device has been created:: + + # mknod /dev/initrd b 1 250 + # chmod 400 /dev/initrd + +Second, the kernel has to be compiled with RAM disk support and with +support for the initial RAM disk enabled. Also, at least all components +needed to execute programs from initrd (e.g. executable format and file +system) must be compiled into the kernel. + +Third, you have to create the RAM disk image. This is done by creating a +file system on a block device, copying files to it as needed, and then +copying the content of the block device to the initrd file. With recent +kernels, at least three types of devices are suitable for that: + + - a floppy disk (works everywhere but it's painfully slow) + - a RAM disk (fast, but allocates physical memory) + - a loopback device (the most elegant solution) + +We'll describe the loopback device method: + + 1) make sure loopback block devices are configured into the kernel + 2) create an empty file system of the appropriate size, e.g.:: + + # dd if=/dev/zero of=initrd bs=300k count=1 + # mke2fs -F -m0 initrd + + (if space is critical, you may want to use the Minix FS instead of Ext2) + 3) mount the file system, e.g.:: + + # mount -t ext2 -o loop initrd /mnt + + 4) create the console device:: + + # mkdir /mnt/dev + # mknod /mnt/dev/console c 5 1 + + 5) copy all the files that are needed to properly use the initrd + environment. Don't forget the most important file, ``/sbin/init`` + + .. note:: ``/sbin/init`` permissions must include "x" (execute). + + 6) correct operation the initrd environment can frequently be tested + even without rebooting with the command:: + + # chroot /mnt /sbin/init + + This is of course limited to initrds that do not interfere with the + general system state (e.g. by reconfiguring network interfaces, + overwriting mounted devices, trying to start already running demons, + etc. Note however that it is usually possible to use pivot_root in + such a chroot'ed initrd environment.) + 7) unmount the file system:: + + # umount /mnt + + 8) the initrd is now in the file "initrd". Optionally, it can now be + compressed:: + + # gzip -9 initrd + +For experimenting with initrd, you may want to take a rescue floppy and +only add a symbolic link from ``/sbin/init`` to ``/bin/sh``. Alternatively, you +can try the experimental newlib environment [#f2]_ to create a small +initrd. + +Finally, you have to boot the kernel and load initrd. Almost all Linux +boot loaders support initrd. Since the boot process is still compatible +with an older mechanism, the following boot command line parameters +have to be given:: + + root=/dev/ram0 rw + +(rw is only necessary if writing to the initrd file system.) + +With LOADLIN, you simply execute:: + + LOADLIN <kernel> initrd=<disk_image> + +e.g.:: + + LOADLIN C:\LINUX\BZIMAGE initrd=C:\LINUX\INITRD.GZ root=/dev/ram0 rw + +With LILO, you add the option ``INITRD=<path>`` to either the global section +or to the section of the respective kernel in ``/etc/lilo.conf``, and pass +the options using APPEND, e.g.:: + + image = /bzImage + initrd = /boot/initrd.gz + append = "root=/dev/ram0 rw" + +and run ``/sbin/lilo`` + +For other boot loaders, please refer to the respective documentation. + +Now you can boot and enjoy using initrd. + + +Changing the root device +------------------------ + +When finished with its duties, init typically changes the root device +and proceeds with starting the Linux system on the "real" root device. + +The procedure involves the following steps: + - mounting the new root file system + - turning it into the root file system + - removing all accesses to the old (initrd) root file system + - unmounting the initrd file system and de-allocating the RAM disk + +Mounting the new root file system is easy: it just needs to be mounted on +a directory under the current root. Example:: + + # mkdir /new-root + # mount -o ro /dev/hda1 /new-root + +The root change is accomplished with the pivot_root system call, which +is also available via the ``pivot_root`` utility (see :manpage:`pivot_root(8)` +man page; ``pivot_root`` is distributed with util-linux version 2.10h or higher +[#f3]_). ``pivot_root`` moves the current root to a directory under the new +root, and puts the new root at its place. The directory for the old root +must exist before calling ``pivot_root``. Example:: + + # cd /new-root + # mkdir initrd + # pivot_root . initrd + +Now, the init process may still access the old root via its +executable, shared libraries, standard input/output/error, and its +current root directory. All these references are dropped by the +following command:: + + # exec chroot . what-follows <dev/console >dev/console 2>&1 + +Where what-follows is a program under the new root, e.g. ``/sbin/init`` +If the new root file system will be used with udev and has no valid +``/dev`` directory, udev must be initialized before invoking chroot in order +to provide ``/dev/console``. + +Note: implementation details of pivot_root may change with time. In order +to ensure compatibility, the following points should be observed: + + - before calling pivot_root, the current directory of the invoking + process should point to the new root directory + - use . as the first argument, and the _relative_ path of the directory + for the old root as the second argument + - a chroot program must be available under the old and the new root + - chroot to the new root afterwards + - use relative paths for dev/console in the exec command + +Now, the initrd can be unmounted and the memory allocated by the RAM +disk can be freed:: + + # umount /initrd + # blockdev --flushbufs /dev/ram0 + +It is also possible to use initrd with an NFS-mounted root, see the +:manpage:`pivot_root(8)` man page for details. + + +Usage scenarios +--------------- + +The main motivation for implementing initrd was to allow for modular +kernel configuration at system installation. The procedure would work +as follows: + + 1) system boots from floppy or other media with a minimal kernel + (e.g. support for RAM disks, initrd, a.out, and the Ext2 FS) and + loads initrd + 2) ``/sbin/init`` determines what is needed to (1) mount the "real" root FS + (i.e. device type, device drivers, file system) and (2) the + distribution media (e.g. CD-ROM, network, tape, ...). This can be + done by asking the user, by auto-probing, or by using a hybrid + approach. + 3) ``/sbin/init`` loads the necessary kernel modules + 4) ``/sbin/init`` creates and populates the root file system (this doesn't + have to be a very usable system yet) + 5) ``/sbin/init`` invokes ``pivot_root`` to change the root file system and + execs - via chroot - a program that continues the installation + 6) the boot loader is installed + 7) the boot loader is configured to load an initrd with the set of + modules that was used to bring up the system (e.g. ``/initrd`` can be + modified, then unmounted, and finally, the image is written from + ``/dev/ram0`` or ``/dev/rd/0`` to a file) + 8) now the system is bootable and additional installation tasks can be + performed + +The key role of initrd here is to re-use the configuration data during +normal system operation without requiring the use of a bloated "generic" +kernel or re-compiling or re-linking the kernel. + +A second scenario is for installations where Linux runs on systems with +different hardware configurations in a single administrative domain. In +such cases, it is desirable to generate only a small set of kernels +(ideally only one) and to keep the system-specific part of configuration +information as small as possible. In this case, a common initrd could be +generated with all the necessary modules. Then, only ``/sbin/init`` or a file +read by it would have to be different. + +A third scenario is more convenient recovery disks, because information +like the location of the root FS partition doesn't have to be provided at +boot time, but the system loaded from initrd can invoke a user-friendly +dialog and it can also perform some sanity checks (or even some form of +auto-detection). + +Last not least, CD-ROM distributors may use it for better installation +from CD, e.g. by using a boot floppy and bootstrapping a bigger RAM disk +via initrd from CD; or by booting via a loader like ``LOADLIN`` or directly +from the CD-ROM, and loading the RAM disk from CD without need of +floppies. + + +Obsolete root change mechanism +------------------------------ + +The following mechanism was used before the introduction of pivot_root. +Current kernels still support it, but you should _not_ rely on its +continued availability. + +It works by mounting the "real" root device (i.e. the one set with rdev +in the kernel image or with root=... at the boot command line) as the +root file system when linuxrc exits. The initrd file system is then +unmounted, or, if it is still busy, moved to a directory ``/initrd``, if +such a directory exists on the new root file system. + +In order to use this mechanism, you do not have to specify the boot +command options root, init, or rw. (If specified, they will affect +the real root file system, not the initrd environment.) + +If /proc is mounted, the "real" root device can be changed from within +linuxrc by writing the number of the new root FS device to the special +file /proc/sys/kernel/real-root-dev, e.g.:: + + # echo 0x301 >/proc/sys/kernel/real-root-dev + +Note that the mechanism is incompatible with NFS and similar file +systems. + +This old, deprecated mechanism is commonly called ``change_root``, while +the new, supported mechanism is called ``pivot_root``. + + +Mixed change_root and pivot_root mechanism +------------------------------------------ + +In case you did not want to use ``root=/dev/ram0`` to trigger the pivot_root +mechanism, you may create both ``/linuxrc`` and ``/sbin/init`` in your initrd +image. + +``/linuxrc`` would contain only the following:: + + #! /bin/sh + mount -n -t proc proc /proc + echo 0x0100 >/proc/sys/kernel/real-root-dev + umount -n /proc + +Once linuxrc exited, the kernel would mount again your initrd as root, +this time executing ``/sbin/init``. Again, it would be the duty of this init +to build the right environment (maybe using the ``root= device`` passed on +the cmdline) before the final execution of the real ``/sbin/init``. + + +Resources +--------- + +.. [#f1] Almesberger, Werner; "Booting Linux: The History and the Future" + http://www.almesberger.net/cv/papers/ols2k-9.ps.gz +.. [#f2] newlib package (experimental), with initrd example + https://www.sourceware.org/newlib/ +.. [#f3] util-linux: Miscellaneous utilities for Linux + https://www.kernel.org/pub/linux/utils/util-linux/ diff --git a/Documentation/admin-guide/java.rst b/Documentation/admin-guide/java.rst new file mode 100644 index 000000000000..8744e272e6f8 --- /dev/null +++ b/Documentation/admin-guide/java.rst @@ -0,0 +1,423 @@ +Java(tm) Binary Kernel Support for Linux v1.03 +---------------------------------------------- + +Linux beats them ALL! While all other OS's are TALKING about direct +support of Java Binaries in the OS, Linux is doing it! + +You can execute Java applications and Java Applets just like any +other program after you have done the following: + +1) You MUST FIRST install the Java Developers Kit for Linux. + The Java on Linux HOWTO gives the details on getting and + installing this. This HOWTO can be found at: + + ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Java-HOWTO + + You should also set up a reasonable CLASSPATH environment + variable to use Java applications that make use of any + nonstandard classes (not included in the same directory + as the application itself). + +2) You have to compile BINFMT_MISC either as a module or into + the kernel (``CONFIG_BINFMT_MISC``) and set it up properly. + If you choose to compile it as a module, you will have + to insert it manually with modprobe/insmod, as kmod + cannot easily be supported with binfmt_misc. + Read the file 'binfmt_misc.txt' in this directory to know + more about the configuration process. + +3) Add the following configuration items to binfmt_misc + (you should really have read ``binfmt_misc.txt`` now): + support for Java applications:: + + ':Java:M::\xca\xfe\xba\xbe::/usr/local/bin/javawrapper:' + + support for executable Jar files:: + + ':ExecutableJAR:E::jar::/usr/local/bin/jarwrapper:' + + support for Java Applets:: + + ':Applet:E::html::/usr/bin/appletviewer:' + + or the following, if you want to be more selective:: + + ':Applet:M::<!--applet::/usr/bin/appletviewer:' + + Of course you have to fix the path names. The path/file names given in this + document match the Debian 2.1 system. (i.e. jdk installed in ``/usr``, + custom wrappers from this document in ``/usr/local``) + + Note, that for the more selective applet support you have to modify + existing html-files to contain ``<!--applet-->`` in the first line + (``<`` has to be the first character!) to let this work! + + For the compiled Java programs you need a wrapper script like the + following (this is because Java is broken in case of the filename + handling), again fix the path names, both in the script and in the + above given configuration string. + + You, too, need the little program after the script. Compile like:: + + gcc -O2 -o javaclassname javaclassname.c + + and stick it to ``/usr/local/bin``. + + Both the javawrapper shellscript and the javaclassname program + were supplied by Colin J. Watson <cjw44@cam.ac.uk>. + +Javawrapper shell script: + +.. code-block:: sh + + #!/bin/bash + # /usr/local/bin/javawrapper - the wrapper for binfmt_misc/java + + if [ -z "$1" ]; then + exec 1>&2 + echo Usage: $0 class-file + exit 1 + fi + + CLASS=$1 + FQCLASS=`/usr/local/bin/javaclassname $1` + FQCLASSN=`echo $FQCLASS | sed -e 's/^.*\.\([^.]*\)$/\1/'` + FQCLASSP=`echo $FQCLASS | sed -e 's-\.-/-g' -e 's-^[^/]*$--' -e 's-/[^/]*$--'` + + # for example: + # CLASS=Test.class + # FQCLASS=foo.bar.Test + # FQCLASSN=Test + # FQCLASSP=foo/bar + + unset CLASSBASE + + declare -i LINKLEVEL=0 + + while :; do + if [ "`basename $CLASS .class`" == "$FQCLASSN" ]; then + # See if this directory works straight off + cd -L `dirname $CLASS` + CLASSDIR=$PWD + cd $OLDPWD + if echo $CLASSDIR | grep -q "$FQCLASSP$"; then + CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."` + break; + fi + # Try dereferencing the directory name + cd -P `dirname $CLASS` + CLASSDIR=$PWD + cd $OLDPWD + if echo $CLASSDIR | grep -q "$FQCLASSP$"; then + CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."` + break; + fi + # If no other possible filename exists + if [ ! -L $CLASS ]; then + exec 1>&2 + echo $0: + echo " $CLASS should be in a" \ + "directory tree called $FQCLASSP" + exit 1 + fi + fi + if [ ! -L $CLASS ]; then break; fi + # Go down one more level of symbolic links + let LINKLEVEL+=1 + if [ $LINKLEVEL -gt 5 ]; then + exec 1>&2 + echo $0: + echo " Too many symbolic links encountered" + exit 1 + fi + CLASS=`ls --color=no -l $CLASS | sed -e 's/^.* \([^ ]*\)$/\1/'` + done + + if [ -z "$CLASSBASE" ]; then + if [ -z "$FQCLASSP" ]; then + GOODNAME=$FQCLASSN.class + else + GOODNAME=$FQCLASSP/$FQCLASSN.class + fi + exec 1>&2 + echo $0: + echo " $FQCLASS should be in a file called $GOODNAME" + exit 1 + fi + + if ! echo $CLASSPATH | grep -q "^\(.*:\)*$CLASSBASE\(:.*\)*"; then + # class is not in CLASSPATH, so prepend dir of class to CLASSPATH + if [ -z "${CLASSPATH}" ] ; then + export CLASSPATH=$CLASSBASE + else + export CLASSPATH=$CLASSBASE:$CLASSPATH + fi + fi + + shift + /usr/bin/java $FQCLASS "$@" + +javaclassname.c: + +.. code-block:: c + + /* javaclassname.c + * + * Extracts the class name from a Java class file; intended for use in a Java + * wrapper of the type supported by the binfmt_misc option in the Linux kernel. + * + * Copyright (C) 1999 Colin J. Watson <cjw44@cam.ac.uk>. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + + #include <stdlib.h> + #include <stdio.h> + #include <stdarg.h> + #include <sys/types.h> + + /* From Sun's Java VM Specification, as tag entries in the constant pool. */ + + #define CP_UTF8 1 + #define CP_INTEGER 3 + #define CP_FLOAT 4 + #define CP_LONG 5 + #define CP_DOUBLE 6 + #define CP_CLASS 7 + #define CP_STRING 8 + #define CP_FIELDREF 9 + #define CP_METHODREF 10 + #define CP_INTERFACEMETHODREF 11 + #define CP_NAMEANDTYPE 12 + #define CP_METHODHANDLE 15 + #define CP_METHODTYPE 16 + #define CP_INVOKEDYNAMIC 18 + + /* Define some commonly used error messages */ + + #define seek_error() error("%s: Cannot seek\n", program) + #define corrupt_error() error("%s: Class file corrupt\n", program) + #define eof_error() error("%s: Unexpected end of file\n", program) + #define utf8_error() error("%s: Only ASCII 1-255 supported\n", program); + + char *program; + + long *pool; + + u_int8_t read_8(FILE *classfile); + u_int16_t read_16(FILE *classfile); + void skip_constant(FILE *classfile, u_int16_t *cur); + void error(const char *format, ...); + int main(int argc, char **argv); + + /* Reads in an unsigned 8-bit integer. */ + u_int8_t read_8(FILE *classfile) + { + int b = fgetc(classfile); + if(b == EOF) + eof_error(); + return (u_int8_t)b; + } + + /* Reads in an unsigned 16-bit integer. */ + u_int16_t read_16(FILE *classfile) + { + int b1, b2; + b1 = fgetc(classfile); + if(b1 == EOF) + eof_error(); + b2 = fgetc(classfile); + if(b2 == EOF) + eof_error(); + return (u_int16_t)((b1 << 8) | b2); + } + + /* Reads in a value from the constant pool. */ + void skip_constant(FILE *classfile, u_int16_t *cur) + { + u_int16_t len; + int seekerr = 1; + pool[*cur] = ftell(classfile); + switch(read_8(classfile)) + { + case CP_UTF8: + len = read_16(classfile); + seekerr = fseek(classfile, len, SEEK_CUR); + break; + case CP_CLASS: + case CP_STRING: + case CP_METHODTYPE: + seekerr = fseek(classfile, 2, SEEK_CUR); + break; + case CP_METHODHANDLE: + seekerr = fseek(classfile, 3, SEEK_CUR); + break; + case CP_INTEGER: + case CP_FLOAT: + case CP_FIELDREF: + case CP_METHODREF: + case CP_INTERFACEMETHODREF: + case CP_NAMEANDTYPE: + case CP_INVOKEDYNAMIC: + seekerr = fseek(classfile, 4, SEEK_CUR); + break; + case CP_LONG: + case CP_DOUBLE: + seekerr = fseek(classfile, 8, SEEK_CUR); + ++(*cur); + break; + default: + corrupt_error(); + } + if(seekerr) + seek_error(); + } + + void error(const char *format, ...) + { + va_list ap; + va_start(ap, format); + vfprintf(stderr, format, ap); + va_end(ap); + exit(1); + } + + int main(int argc, char **argv) + { + FILE *classfile; + u_int16_t cp_count, i, this_class, classinfo_ptr; + u_int8_t length; + + program = argv[0]; + + if(!argv[1]) + error("%s: Missing input file\n", program); + classfile = fopen(argv[1], "rb"); + if(!classfile) + error("%s: Error opening %s\n", program, argv[1]); + + if(fseek(classfile, 8, SEEK_SET)) /* skip magic and version numbers */ + seek_error(); + cp_count = read_16(classfile); + pool = calloc(cp_count, sizeof(long)); + if(!pool) + error("%s: Out of memory for constant pool\n", program); + + for(i = 1; i < cp_count; ++i) + skip_constant(classfile, &i); + if(fseek(classfile, 2, SEEK_CUR)) /* skip access flags */ + seek_error(); + + this_class = read_16(classfile); + if(this_class < 1 || this_class >= cp_count) + corrupt_error(); + if(!pool[this_class] || pool[this_class] == -1) + corrupt_error(); + if(fseek(classfile, pool[this_class] + 1, SEEK_SET)) + seek_error(); + + classinfo_ptr = read_16(classfile); + if(classinfo_ptr < 1 || classinfo_ptr >= cp_count) + corrupt_error(); + if(!pool[classinfo_ptr] || pool[classinfo_ptr] == -1) + corrupt_error(); + if(fseek(classfile, pool[classinfo_ptr] + 1, SEEK_SET)) + seek_error(); + + length = read_16(classfile); + for(i = 0; i < length; ++i) + { + u_int8_t x = read_8(classfile); + if((x & 0x80) || !x) + { + if((x & 0xE0) == 0xC0) + { + u_int8_t y = read_8(classfile); + if((y & 0xC0) == 0x80) + { + int c = ((x & 0x1f) << 6) + (y & 0x3f); + if(c) putchar(c); + else utf8_error(); + } + else utf8_error(); + } + else utf8_error(); + } + else if(x == '/') putchar('.'); + else putchar(x); + } + putchar('\n'); + free(pool); + fclose(classfile); + return 0; + } + +jarwrapper:: + + #!/bin/bash + # /usr/local/java/bin/jarwrapper - the wrapper for binfmt_misc/jar + + java -jar $1 + + +Now simply ``chmod +x`` the ``.class``, ``.jar`` and/or ``.html`` files you +want to execute. + +To add a Java program to your path best put a symbolic link to the main +.class file into /usr/bin (or another place you like) omitting the .class +extension. The directory containing the original .class file will be +added to your CLASSPATH during execution. + + +To test your new setup, enter in the following simple Java app, and name +it "HelloWorld.java": + +.. code-block:: java + + class HelloWorld { + public static void main(String args[]) { + System.out.println("Hello World!"); + } + } + +Now compile the application with:: + + javac HelloWorld.java + +Set the executable permissions of the binary file, with:: + + chmod 755 HelloWorld.class + +And then execute it:: + + ./HelloWorld.class + + +To execute Java Jar files, simple chmod the ``*.jar`` files to include +the execution bit, then just do:: + + ./Application.jar + + +To execute Java Applets, simple chmod the ``*.html`` files to include +the execution bit, then just do:: + + ./Applet.html + + +originally by Brian A. Lantz, brian@lantz.com +heavily edited for binfmt_misc by Richard Günther +new scripts by Colin J. Watson <cjw44@cam.ac.uk> +added executable Jar file support by Kurt Huwig <kurt@iku-netz.de> diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst new file mode 100644 index 000000000000..b516164999a8 --- /dev/null +++ b/Documentation/admin-guide/kernel-parameters.rst @@ -0,0 +1,209 @@ +The kernel's command-line parameters +==================================== + +The following is a consolidated list of the kernel parameters as +implemented by the __setup(), core_param() and module_param() macros +and sorted into English Dictionary order (defined as ignoring all +punctuation and sorting digits before letters in a case insensitive +manner), and with descriptions where known. + +The kernel parses parameters from the kernel command line up to "--"; +if it doesn't recognize a parameter and it doesn't contain a '.', the +parameter gets passed to init: parameters with '=' go into init's +environment, others are passed as command line arguments to init. +Everything after "--" is passed as an argument to init. + +Module parameters can be specified in two ways: via the kernel command +line with a module name prefix, or via modprobe, e.g.:: + + (kernel command line) usbcore.blinkenlights=1 + (modprobe command line) modprobe usbcore blinkenlights=1 + +Parameters for modules which are built into the kernel need to be +specified on the kernel command line. modprobe looks through the +kernel command line (/proc/cmdline) and collects module parameters +when it loads a module, so the kernel command line can be used for +loadable modules too. + +Hyphens (dashes) and underscores are equivalent in parameter names, so:: + + log_buf_len=1M print-fatal-signals=1 + +can also be entered as:: + + log-buf-len=1M print_fatal_signals=1 + +Double-quotes can be used to protect spaces in values, e.g.:: + + param="spaces in here" + +cpu lists: +---------- + +Some kernel parameters take a list of CPUs as a value, e.g. isolcpus, +nohz_full, irqaffinity, rcu_nocbs. The format of this list is: + + <cpu number>,...,<cpu number> + +or + + <cpu number>-<cpu number> + (must be a positive range in ascending order) + +or a mixture + +<cpu number>,...,<cpu number>-<cpu number> + +Note that for the special case of a range one can split the range into equal +sized groups and for each group use some amount from the beginning of that +group: + + <cpu number>-cpu number>:<used size>/<group size> + +For example one can add to the command line following parameter: + + isolcpus=1,2,10-20,100-2000:2/25 + +where the final item represents CPUs 100,101,125,126,150,151,... + + + +This document may not be entirely up to date and comprehensive. The command +"modinfo -p ${modulename}" shows a current list of all parameters of a loadable +module. Loadable modules, after being loaded into the running kernel, also +reveal their parameters in /sys/module/${modulename}/parameters/. Some of these +parameters may be changed at runtime by the command +``echo -n ${value} > /sys/module/${modulename}/parameters/${parm}``. + +The parameters listed below are only valid if certain kernel build options were +enabled and if respective hardware is present. The text in square brackets at +the beginning of each description states the restrictions within which a +parameter is applicable:: + + ACPI ACPI support is enabled. + AGP AGP (Accelerated Graphics Port) is enabled. + ALSA ALSA sound support is enabled. + APIC APIC support is enabled. + APM Advanced Power Management support is enabled. + ARM ARM architecture is enabled. + AVR32 AVR32 architecture is enabled. + AX25 Appropriate AX.25 support is enabled. + BLACKFIN Blackfin architecture is enabled. + CLK Common clock infrastructure is enabled. + CMA Contiguous Memory Area support is enabled. + DRM Direct Rendering Management support is enabled. + DYNAMIC_DEBUG Build in debug messages and enable them at runtime + EDD BIOS Enhanced Disk Drive Services (EDD) is enabled + EFI EFI Partitioning (GPT) is enabled + EIDE EIDE/ATAPI support is enabled. + EVM Extended Verification Module + FB The frame buffer device is enabled. + FTRACE Function tracing enabled. + GCOV GCOV profiling is enabled. + HW Appropriate hardware is enabled. + IA-64 IA-64 architecture is enabled. + IMA Integrity measurement architecture is enabled. + IOSCHED More than one I/O scheduler is enabled. + IP_PNP IP DHCP, BOOTP, or RARP is enabled. + IPV6 IPv6 support is enabled. + ISAPNP ISA PnP code is enabled. + ISDN Appropriate ISDN support is enabled. + JOY Appropriate joystick support is enabled. + KGDB Kernel debugger support is enabled. + KVM Kernel Virtual Machine support is enabled. + LIBATA Libata driver is enabled + LP Printer support is enabled. + LOOP Loopback device support is enabled. + M68k M68k architecture is enabled. + These options have more detailed description inside of + Documentation/m68k/kernel-options.txt. + MDA MDA console support is enabled. + MIPS MIPS architecture is enabled. + MOUSE Appropriate mouse support is enabled. + MSI Message Signaled Interrupts (PCI). + MTD MTD (Memory Technology Device) support is enabled. + NET Appropriate network support is enabled. + NUMA NUMA support is enabled. + NFS Appropriate NFS support is enabled. + OSS OSS sound support is enabled. + PV_OPS A paravirtualized kernel is enabled. + PARIDE The ParIDE (parallel port IDE) subsystem is enabled. + PARISC The PA-RISC architecture is enabled. + PCI PCI bus support is enabled. + PCIE PCI Express support is enabled. + PCMCIA The PCMCIA subsystem is enabled. + PNP Plug & Play support is enabled. + PPC PowerPC architecture is enabled. + PPT Parallel port support is enabled. + PS2 Appropriate PS/2 support is enabled. + RAM RAM disk support is enabled. + S390 S390 architecture is enabled. + SCSI Appropriate SCSI support is enabled. + A lot of drivers have their options described inside + the Documentation/scsi/ sub-directory. + SECURITY Different security models are enabled. + SELINUX SELinux support is enabled. + APPARMOR AppArmor support is enabled. + SERIAL Serial support is enabled. + SH SuperH architecture is enabled. + SMP The kernel is an SMP kernel. + SPARC Sparc architecture is enabled. + SWSUSP Software suspend (hibernation) is enabled. + SUSPEND System suspend states are enabled. + TPM TPM drivers are enabled. + TS Appropriate touchscreen support is enabled. + UMS USB Mass Storage support is enabled. + USB USB support is enabled. + USBHID USB Human Interface Device support is enabled. + V4L Video For Linux support is enabled. + VMMIO Driver for memory mapped virtio devices is enabled. + VGA The VGA console has been enabled. + VT Virtual terminal support is enabled. + WDT Watchdog support is enabled. + XT IBM PC/XT MFM hard disk support is enabled. + X86-32 X86-32, aka i386 architecture is enabled. + X86-64 X86-64 architecture is enabled. + More X86-64 boot options can be found in + Documentation/x86/x86_64/boot-options.txt . + X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64) + X86_UV SGI UV support is enabled. + XEN Xen support is enabled + +In addition, the following text indicates that the option:: + + BUGS= Relates to possible processor bugs on the said processor. + KNL Is a kernel start-up parameter. + BOOT Is a boot loader parameter. + +Parameters denoted with BOOT are actually interpreted by the boot +loader, and have no meaning to the kernel directly. +Do not modify the syntax of boot loader parameters without extreme +need or coordination with <Documentation/x86/boot.txt>. + +There are also arch-specific kernel-parameters not documented here. +See for example <Documentation/x86/x86_64/boot-options.txt>. + +Note that ALL kernel parameters listed below are CASE SENSITIVE, and that +a trailing = on the name of any parameter states that that parameter will +be entered as an environment variable, whereas its absence indicates that +it will appear as a kernel argument readable via /proc/cmdline by programs +running once the system is up. + +The number of kernel parameters is not limited, but the length of the +complete command line (parameters including spaces etc.) is limited to +a fixed number of characters. This limit depends on the architecture +and is between 256 and 4096 characters. It is defined in the file +./include/asm/setup.h as COMMAND_LINE_SIZE. + +Finally, the [KMG] suffix is commonly described after a number of kernel +parameter values. These 'K', 'M', and 'G' letters represent the _binary_ +multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30 +bytes respectively. Such letter suffixes can also be entirely omitted: + +.. include:: kernel-parameters.txt + :literal: + +Todo +---- + + Add more DRM drivers. diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt new file mode 100644 index 000000000000..21e2d8863705 --- /dev/null +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -0,0 +1,4379 @@ + acpi= [HW,ACPI,X86,ARM64] + Advanced Configuration and Power Interface + Format: { force | on | off | strict | noirq | rsdt | + copy_dsdt } + force -- enable ACPI if default was off + on -- enable ACPI but allow fallback to DT [arm64] + off -- disable ACPI if default was on + noirq -- do not use ACPI for IRQ routing + strict -- Be less tolerant of platforms that are not + strictly ACPI specification compliant. + rsdt -- prefer RSDT over (default) XSDT + copy_dsdt -- copy DSDT to memory + For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force" + are available + + See also Documentation/power/runtime_pm.txt, pci=noacpi + + acpi_apic_instance= [ACPI, IOAPIC] + Format: <int> + 2: use 2nd APIC table, if available + 1,0: use 1st APIC table + default: 0 + + acpi_backlight= [HW,ACPI] + acpi_backlight=vendor + acpi_backlight=video + If set to vendor, prefer vendor specific driver + (e.g. thinkpad_acpi, sony_acpi, etc.) instead + of the ACPI video.ko driver. + + acpi_force_32bit_fadt_addr + force FADT to use 32 bit addresses rather than the + 64 bit X_* addresses. Some firmware have broken 64 + bit addresses for force ACPI ignore these and use + the older legacy 32 bit addresses. + + acpica_no_return_repair [HW, ACPI] + Disable AML predefined validation mechanism + This mechanism can repair the evaluation result to make + the return objects more ACPI specification compliant. + This option is useful for developers to identify the + root cause of an AML interpreter issue when the issue + has something to do with the repair mechanism. + + acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] + acpi.debug_level= [HW,ACPI,ACPI_DEBUG] + Format: <int> + CONFIG_ACPI_DEBUG must be enabled to produce any ACPI + debug output. Bits in debug_layer correspond to a + _COMPONENT in an ACPI source file, e.g., + #define _COMPONENT ACPI_PCI_COMPONENT + Bits in debug_level correspond to a level in + ACPI_DEBUG_PRINT statements, e.g., + ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... + The debug_level mask defaults to "info". See + Documentation/acpi/debug.txt for more information about + debug layers and levels. + + Enable processor driver info messages: + acpi.debug_layer=0x20000000 + Enable PCI/PCI interrupt routing info messages: + acpi.debug_layer=0x400000 + Enable AML "Debug" output, i.e., stores to the Debug + object while interpreting AML: + acpi.debug_layer=0xffffffff acpi.debug_level=0x2 + Enable all messages related to ACPI hardware: + acpi.debug_layer=0x2 acpi.debug_level=0xffffffff + + Some values produce so much output that the system is + unusable. The "log_buf_len" parameter may be useful + if you need to capture more output. + + acpi_enforce_resources= [ACPI] + { strict | lax | no } + Check for resource conflicts between native drivers + and ACPI OperationRegions (SystemIO and SystemMemory + only). IO ports and memory declared in ACPI might be + used by the ACPI subsystem in arbitrary AML code and + can interfere with legacy drivers. + strict (default): access to resources claimed by ACPI + is denied; legacy drivers trying to access reserved + resources will fail to bind to device using them. + lax: access to resources claimed by ACPI is allowed; + legacy drivers trying to access reserved resources + will bind successfully but a warning message is logged. + no: ACPI OperationRegions are not marked as reserved, + no further checks are performed. + + acpi_force_table_verification [HW,ACPI] + Enable table checksum verification during early stage. + By default, this is disabled due to x86 early mapping + size limitation. + + acpi_irq_balance [HW,ACPI] + ACPI will balance active IRQs + default in APIC mode + + acpi_irq_nobalance [HW,ACPI] + ACPI will not move active IRQs (default) + default in PIC mode + + acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA + Format: <irq>,<irq>... + + acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for + use by PCI + Format: <irq>,<irq>... + + acpi_no_auto_serialize [HW,ACPI] + Disable auto-serialization of AML methods + AML control methods that contain the opcodes to create + named objects will be marked as "Serialized" by the + auto-serialization feature. + This feature is enabled by default. + This option allows to turn off the feature. + + acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump + kernels. + + acpi_no_static_ssdt [HW,ACPI] + Disable installation of static SSDTs at early boot time + By default, SSDTs contained in the RSDT/XSDT will be + installed automatically and they will appear under + /sys/firmware/acpi/tables. + This option turns off this feature. + Note that specifying this option does not affect + dynamic table installation which will install SSDT + tables to /sys/firmware/acpi/tables/dynamic. + + acpi_rsdp= [ACPI,EFI,KEXEC] + Pass the RSDP address to the kernel, mostly used + on machines running EFI runtime service to boot the + second kernel for kdump. + + acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS + Format: To spoof as Windows 98: ="Microsoft Windows" + + acpi_rev_override [ACPI] Override the _REV object to return 5 (instead + of 2 which is mandated by ACPI 6) as the supported ACPI + specification revision (when using this switch, it may + be necessary to carry out a cold reboot _twice_ in a + row to make it take effect on the platform firmware). + + acpi_osi= [HW,ACPI] Modify list of supported OS interface strings + acpi_osi="string1" # add string1 + acpi_osi="!string2" # remove string2 + acpi_osi=!* # remove all strings + acpi_osi=! # disable all built-in OS vendor + strings + acpi_osi=!! # enable all built-in OS vendor + strings + acpi_osi= # disable all strings + + 'acpi_osi=!' can be used in combination with single or + multiple 'acpi_osi="string1"' to support specific OS + vendor string(s). Note that such command can only + affect the default state of the OS vendor strings, thus + it cannot affect the default state of the feature group + strings and the current state of the OS vendor strings, + specifying it multiple times through kernel command line + is meaningless. This command is useful when one do not + care about the state of the feature group strings which + should be controlled by the OSPM. + Examples: + 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent + to 'acpi_osi="Windows 2000" acpi_osi=!', they all + can make '_OSI("Windows 2000")' TRUE. + + 'acpi_osi=' cannot be used in combination with other + 'acpi_osi=' command lines, the _OSI method will not + exist in the ACPI namespace. NOTE that such command can + only affect the _OSI support state, thus specifying it + multiple times through kernel command line is also + meaningless. + Examples: + 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' + FALSE. + + 'acpi_osi=!*' can be used in combination with single or + multiple 'acpi_osi="string1"' to support specific + string(s). Note that such command can affect the + current state of both the OS vendor strings and the + feature group strings, thus specifying it multiple times + through kernel command line is meaningful. But it may + still not able to affect the final state of a string if + there are quirks related to this string. This command + is useful when one want to control the state of the + feature group strings to debug BIOS issues related to + the OSPM features. + Examples: + 1. 'acpi_osi="Module Device" acpi_osi=!*' can make + '_OSI("Module Device")' FALSE. + 2. 'acpi_osi=!* acpi_osi="Module Device"' can make + '_OSI("Module Device")' TRUE. + 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is + equivalent to + 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' + and + 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', + they all will make '_OSI("Windows 2000")' TRUE. + + acpi_pm_good [X86] + Override the pmtimer bug detection: force the kernel + to assume that this machine's pmtimer latches its value + and always returns good values. + + acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode + Format: { level | edge | high | low } + + acpi_skip_timer_override [HW,ACPI] + Recognize and ignore IRQ0/pin2 Interrupt Override. + For broken nForce2 BIOS resulting in XT-PIC timer. + + acpi_sleep= [HW,ACPI] Sleep options + Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, + old_ordering, nonvs, sci_force_enable } + See Documentation/power/video.txt for information on + s3_bios and s3_mode. + s3_beep is for debugging; it makes the PC's speaker beep + as soon as the kernel's real-mode entry point is called. + s4_nohwsig prevents ACPI hardware signature from being + used during resume from hibernation. + old_ordering causes the ACPI 1.0 ordering of the _PTS + control method, with respect to putting devices into + low power states, to be enforced (the ACPI 2.0 ordering + of _PTS is used by default). + nonvs prevents the kernel from saving/restoring the + ACPI NVS memory during suspend/hibernation and resume. + sci_force_enable causes the kernel to set SCI_EN directly + on resume from S1/S3 (which is against the ACPI spec, + but some broken systems don't work without it). + + acpi_use_timer_override [HW,ACPI] + Use timer override. For some broken Nvidia NF5 boards + that require a timer override, but don't have HPET + + add_efi_memmap [EFI; X86] Include EFI memory map in + kernel's map of available physical RAM. + + agp= [AGP] + { off | try_unsupported } + off: disable AGP support + try_unsupported: try to drive unsupported chipsets + (may crash computer or cause data corruption) + + ALSA [HW,ALSA] + See Documentation/sound/alsa/alsa-parameters.txt + + alignment= [KNL,ARM] + Allow the default userspace alignment fault handler + behaviour to be specified. Bit 0 enables warnings, + bit 1 enables fixups, and bit 2 sends a segfault. + + align_va_addr= [X86-64] + Align virtual addresses by clearing slice [14:12] when + allocating a VMA at process creation time. This option + gives you up to 3% performance improvement on AMD F15h + machines (where it is enabled by default) for a + CPU-intensive style benchmark, and it can vary highly in + a microbenchmark depending on workload and compiler. + + 32: only for 32-bit processes + 64: only for 64-bit processes + on: enable for both 32- and 64-bit processes + off: disable for both 32- and 64-bit processes + + alloc_snapshot [FTRACE] + Allocate the ftrace snapshot buffer on boot up when the + main buffer is allocated. This is handy if debugging + and you need to use tracing_snapshot() on boot up, and + do not want to use tracing_snapshot_alloc() as it needs + to be done where GFP_KERNEL allocations are allowed. + + amd_iommu= [HW,X86-64] + Pass parameters to the AMD IOMMU driver in the system. + Possible values are: + fullflush - enable flushing of IO/TLB entries when + they are unmapped. Otherwise they are + flushed before they will be reused, which + is a lot of faster + off - do not initialize any AMD IOMMU found in + the system + force_isolation - Force device isolation for all + devices. The IOMMU driver is not + allowed anymore to lift isolation + requirements as needed. This option + does not override iommu=pt + + amd_iommu_dump= [HW,X86-64] + Enable AMD IOMMU driver option to dump the ACPI table + for AMD IOMMU. With this option enabled, AMD IOMMU + driver will print ACPI tables for AMD IOMMU during + IOMMU initialization. + + amd_iommu_intr= [HW,X86-64] + Specifies one of the following AMD IOMMU interrupt + remapping modes: + legacy - Use legacy interrupt remapping mode. + vapic - Use virtual APIC mode, which allows IOMMU + to inject interrupts directly into guest. + This mode requires kvm-amd.avic=1. + (Default when IOMMU HW support is present.) + + amijoy.map= [HW,JOY] Amiga joystick support + Map of devices attached to JOY0DAT and JOY1DAT + Format: <a>,<b> + See also Documentation/input/joystick.txt + + analog.map= [HW,JOY] Analog joystick and gamepad support + Specifies type or capabilities of an analog joystick + connected to one of 16 gameports + Format: <type1>,<type2>,..<type16> + + apc= [HW,SPARC] + Power management functions (SPARCstation-4/5 + deriv.) + Format: noidle + Disable APC CPU standby support. SPARCstation-Fox does + not play well with APC CPU idle - disable it if you have + APC and your system crashes randomly. + + apic= [APIC,X86-32] Advanced Programmable Interrupt Controller + Change the output verbosity whilst booting + Format: { quiet (default) | verbose | debug } + Change the amount of debugging information output + when initialising the APIC and IO-APIC components. + + apic_extnmi= [APIC,X86] External NMI delivery setting + Format: { bsp (default) | all | none } + bsp: External NMI is delivered only to CPU 0 + all: External NMIs are broadcast to all CPUs as a + backup of CPU 0 + none: External NMI is masked for all CPUs. This is + useful so that a dump capture kernel won't be + shot down by NMI + + autoconf= [IPV6] + See Documentation/networking/ipv6.txt. + + show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller + Limit apic dumping. The parameter defines the maximal + number of local apics being dumped. Also it is possible + to set it to "all" by meaning -- no limit here. + Format: { 1 (default) | 2 | ... | all }. + The parameter valid if only apic=debug or + apic=verbose is specified. + Example: apic=debug show_lapic=all + + apm= [APM] Advanced Power Management + See header of arch/x86/kernel/apm_32.c. + + arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards + Format: <io>,<irq>,<nodeID> + + ataflop= [HW,M68k] + + atarimouse= [HW,MOUSE] Atari Mouse + + atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, + EzKey and similar keyboards + + atkbd.reset= [HW] Reset keyboard during initialization + + atkbd.set= [HW] Select keyboard code set + Format: <int> (2 = AT (default), 3 = PS/2) + + atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar + keyboards + + atkbd.softraw= [HW] Choose between synthetic and real raw mode + Format: <bool> (0 = real, 1 = synthetic (default)) + + atkbd.softrepeat= [HW] + Use software keyboard repeat + + audit= [KNL] Enable the audit sub-system + Format: { "0" | "1" } (0 = disabled, 1 = enabled) + 0 - kernel audit is disabled and can not be enabled + until the next reboot + unset - kernel audit is initialized but disabled and + will be fully enabled by the userspace auditd. + 1 - kernel audit is initialized and partially enabled, + storing at most audit_backlog_limit messages in + RAM until it is fully enabled by the userspace + auditd. + Default: unset + + audit_backlog_limit= [KNL] Set the audit queue size limit. + Format: <int> (must be >=0) + Default: 64 + + bau= [X86_UV] Enable the BAU on SGI UV. The default + behavior is to disable the BAU (i.e. bau=0). + Format: { "0" | "1" } + 0 - Disable the BAU. + 1 - Enable the BAU. + unset - Disable the BAU. + + baycom_epp= [HW,AX25] + Format: <io>,<mode> + + baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem + Format: <io>,<mode> + See header of drivers/net/hamradio/baycom_par.c. + + baycom_ser_fdx= [HW,AX25] + BayCom Serial Port AX.25 Modem (Full Duplex Mode) + Format: <io>,<irq>,<mode>[,<baud>] + See header of drivers/net/hamradio/baycom_ser_fdx.c. + + baycom_ser_hdx= [HW,AX25] + BayCom Serial Port AX.25 Modem (Half Duplex Mode) + Format: <io>,<irq>,<mode> + See header of drivers/net/hamradio/baycom_ser_hdx.c. + + blkdevparts= Manual partition parsing of block device(s) for + embedded devices based on command line input. + See Documentation/block/cmdline-partition.txt + + boot_delay= Milliseconds to delay each printk during boot. + Values larger than 10 seconds (10000) are changed to + no delay (0). + Format: integer + + bootmem_debug [KNL] Enable bootmem allocator debug messages. + + bert_disable [ACPI] + Disable BERT OS support on buggy BIOSes. + + bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) + bttv.radio= Most important insmod options are available as + kernel args too. + bttv.pll= See Documentation/video4linux/bttv/Insmod-options + bttv.tuner= + + bulk_remove=off [PPC] This parameter disables the use of the pSeries + firmware feature for flushing multiple hpte entries + at a time. + + c101= [NET] Moxa C101 synchronous serial card + + cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. + Sometimes CPU hardware bugs make them report the cache + size incorrectly. The kernel will attempt work arounds + to fix known problems, but for some CPUs it is not + possible to determine what the correct size should be. + This option provides an override for these situations. + + ca_keys= [KEYS] This parameter identifies a specific key(s) on + the system trusted keyring to be used for certificate + trust validation. + format: { id:<keyid> | builtin } + + cca= [MIPS] Override the kernel pages' cache coherency + algorithm. Accepted values range from 0 to 7 + inclusive. See arch/mips/include/asm/pgtable-bits.h + for platform specific values (SB1, Loongson3 and + others). + + ccw_timeout_log [S390] + See Documentation/s390/CommonIO for details. + + cgroup_disable= [KNL] Disable a particular controller + Format: {name of the controller(s) to disable} + The effects of cgroup_disable=foo are: + - foo isn't auto-mounted if you mount all cgroups in + a single hierarchy + - foo isn't visible as an individually mountable + subsystem + {Currently only "memory" controller deal with this and + cut the overhead, others just disable the usage. So + only cgroup_disable=memory is actually worthy} + + cgroup_no_v1= [KNL] Disable one, multiple, all cgroup controllers in v1 + Format: { controller[,controller...] | "all" } + Like cgroup_disable, but only applies to cgroup v1; + the blacklisted controllers remain available in cgroup2. + + cgroup.memory= [KNL] Pass options to the cgroup memory controller. + Format: <string> + nosocket -- Disable socket memory accounting. + nokmem -- Disable kernel memory accounting. + + checkreqprot [SELINUX] Set initial checkreqprot flag value. + Format: { "0" | "1" } + See security/selinux/Kconfig help text. + 0 -- check protection applied by kernel (includes + any implied execute protection). + 1 -- check protection requested by application. + Default value is set via a kernel config option. + Value can be changed at runtime via + /selinux/checkreqprot. + + cio_ignore= [S390] + See Documentation/s390/CommonIO for details. + clk_ignore_unused + [CLK] + Prevents the clock framework from automatically gating + clocks that have not been explicitly enabled by a Linux + device driver but are enabled in hardware at reset or + by the bootloader/firmware. Note that this does not + force such clocks to be always-on nor does it reserve + those clocks in any way. This parameter is useful for + debug and development, but should not be needed on a + platform with proper driver support. For more + information, see Documentation/clk.txt. + + clock= [BUGS=X86-32, HW] gettimeofday clocksource override. + [Deprecated] + Forces specified clocksource (if available) to be used + when calculating gettimeofday(). If specified + clocksource is not available, it defaults to PIT. + Format: { pit | tsc | cyclone | pmtmr } + + clocksource= Override the default clocksource + Format: <string> + Override the default clocksource and use the clocksource + with the name specified. + Some clocksource names to choose from, depending on + the platform: + [all] jiffies (this is the base, fallback clocksource) + [ACPI] acpi_pm + [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, + pxa_timer,timer3,32k_counter,timer0_1 + [AVR32] avr32 + [X86-32] pit,hpet,tsc; + scx200_hrt on Geode; cyclone on IBM x440 + [MIPS] MIPS + [PARISC] cr16 + [S390] tod + [SH] SuperH + [SPARC64] tick + [X86-64] hpet,tsc + + clocksource.arm_arch_timer.evtstrm= + [ARM,ARM64] + Format: <bool> + Enable/disable the eventstream feature of the ARM + architected timer so that code using WFE-based polling + loops can be debugged more effectively on production + systems. + + clocksource.arm_arch_timer.fsl-a008585= + [ARM64] + Format: <bool> + Enable/disable the workaround of Freescale/NXP + erratum A-008585. This can be useful for KVM + guests, if the guest device tree doesn't show the + erratum. If unspecified, the workaround is + enabled based on the device tree. + + clearcpuid=BITNUM [X86] + Disable CPUID feature X for the kernel. See + arch/x86/include/asm/cpufeatures.h for the valid bit + numbers. Note the Linux specific bits are not necessarily + stable over kernel options, but the vendor specific + ones should be. + Also note that user programs calling CPUID directly + or using the feature without checking anything + will still see it. This just prevents it from + being used by the kernel or shown in /proc/cpuinfo. + Also note the kernel might malfunction if you disable + some critical bits. + + cma=nn[MG]@[start[MG][-end[MG]]] + [ARM,X86,KNL] + Sets the size of kernel global memory area for + contiguous memory allocations and optionally the + placement constraint by the physical address range of + memory allocations. A value of 0 disables CMA + altogether. For more information, see + include/linux/dma-contiguous.h + + cmo_free_hint= [PPC] Format: { yes | no } + Specify whether pages are marked as being inactive + when they are freed. This is used in CMO environments + to determine OS memory pressure for page stealing by + a hypervisor. + Default: yes + + coherent_pool=nn[KMG] [ARM,KNL] + Sets the size of memory pool for coherent, atomic dma + allocations, by default set to 256K. + + code_bytes [X86] How many bytes of object code to print + in an oops report. + Range: 0 - 8192 + Default: 64 + + com20020= [HW,NET] ARCnet - COM20020 chipset + Format: + <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] + + com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) + Format: <io>[,<irq>] + + com90xx= [HW,NET] + ARCnet - COM90xx chipset (memory-mapped buffers) + Format: <io>[,<irq>[,<memstart>]] + + condev= [HW,S390] console device + conmode= + + console= [KNL] Output console device and options. + + tty<n> Use the virtual console device <n>. + + ttyS<n>[,options] + ttyUSB0[,options] + Use the specified serial port. The options are of + the form "bbbbpnf", where "bbbb" is the baud rate, + "p" is parity ("n", "o", or "e"), "n" is number of + bits, and "f" is flow control ("r" for RTS or + omit it). Default is "9600n8". + + See Documentation/admin-guide/serial-console.rst for more + information. See + Documentation/networking/netconsole.txt for an + alternative. + + uart[8250],io,<addr>[,options] + uart[8250],mmio,<addr>[,options] + uart[8250],mmio16,<addr>[,options] + uart[8250],mmio32,<addr>[,options] + uart[8250],0x<addr>[,options] + Start an early, polled-mode console on the 8250/16550 + UART at the specified I/O port or MMIO address, + switching to the matching ttyS device later. + MMIO inter-register address stride is either 8-bit + (mmio), 16-bit (mmio16), or 32-bit (mmio32). + If none of [io|mmio|mmio16|mmio32], <addr> is assumed + to be equivalent to 'mmio'. 'options' are specified in + the same format described for ttyS above; if unspecified, + the h/w is not re-initialized. + + hvc<n> Use the hypervisor console device <n>. This is for + both Xen and PowerPC hypervisors. + + If the device connected to the port is not a TTY but a braille + device, prepend "brl," before the device type, for instance + console=brl,ttyS0 + For now, only VisioBraille is supported. + + consoleblank= [KNL] The console blank (screen saver) timeout in + seconds. Defaults to 10*60 = 10mins. A value of 0 + disables the blank timer. + + coredump_filter= + [KNL] Change the default value for + /proc/<pid>/coredump_filter. + See also Documentation/filesystems/proc.txt. + + cpuidle.off=1 [CPU_IDLE] + disable the cpuidle sub-system + + cpu_init_udelay=N + [X86] Delay for N microsec between assert and de-assert + of APIC INIT to start processors. This delay occurs + on every CPU online, such as boot, and resume from suspend. + Default: 10000 + + cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver + Format: + <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] + + crashkernel=size[KMG][@offset[KMG]] + [KNL] Using kexec, Linux can switch to a 'crash kernel' + upon panic. This parameter reserves the physical + memory region [offset, offset + size] for that kernel + image. If '@offset' is omitted, then a suitable offset + is selected automatically. Check + Documentation/kdump/kdump.txt for further details. + + crashkernel=range1:size1[,range2:size2,...][@offset] + [KNL] Same as above, but depends on the memory + in the running system. The syntax of range is + start-[end] where start and end are both + a memory unit (amount[KMG]). See also + Documentation/kdump/kdump.txt for an example. + + crashkernel=size[KMG],high + [KNL, x86_64] range could be above 4G. Allow kernel + to allocate physical memory region from top, so could + be above 4G if system have more than 4G ram installed. + Otherwise memory region will be allocated below 4G, if + available. + It will be ignored if crashkernel=X is specified. + crashkernel=size[KMG],low + [KNL, x86_64] range under 4G. When crashkernel=X,high + is passed, kernel could allocate physical memory region + above 4G, that cause second kernel crash on system + that require some amount of low memory, e.g. swiotlb + requires at least 64M+32K low memory, also enough extra + low memory is needed to make sure DMA buffers for 32-bit + devices won't run out. Kernel would try to allocate at + at least 256M below 4G automatically. + This one let user to specify own low range under 4G + for second kernel instead. + 0: to disable low allocation. + It will be ignored when crashkernel=X,high is not used + or memory reserved is below 4G. + + cryptomgr.notests + [KNL] Disable crypto self-tests + + cs89x0_dma= [HW,NET] + Format: <dma> + + cs89x0_media= [HW,NET] + Format: { rj45 | aui | bnc } + + dasd= [HW,NET] + See header of drivers/s390/block/dasd_devmap.c. + + db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port + (one device per port) + Format: <port#>,<type> + See also Documentation/input/joystick-parport.txt + + ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot + time. See Documentation/dynamic-debug-howto.txt for + details. Deprecated, see dyndbg. + + debug [KNL] Enable kernel debugging (events log level). + + debug_locks_verbose= + [KNL] verbose self-tests + Format=<0|1> + Print debugging info while doing the locking API + self-tests. + We default to 0 (no extra messages), setting it to + 1 will print _a lot_ more information - normally + only useful to kernel developers. + + debug_objects [KNL] Enable object debugging + + no_debug_objects + [KNL] Disable object debugging + + debug_guardpage_minorder= + [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this + parameter allows control of the order of pages that will + be intentionally kept free (and hence protected) by the + buddy allocator. Bigger value increase the probability + of catching random memory corruption, but reduce the + amount of memory for normal system use. The maximum + possible value is MAX_ORDER/2. Setting this parameter + to 1 or 2 should be enough to identify most random + memory corruption problems caused by bugs in kernel or + driver code when a CPU writes to (or reads from) a + random memory location. Note that there exists a class + of memory corruptions problems caused by buggy H/W or + F/W or by drivers badly programing DMA (basically when + memory is written at bus level and the CPU MMU is + bypassed) which are not detectable by + CONFIG_DEBUG_PAGEALLOC, hence this option will not help + tracking down these problems. + + debug_pagealloc= + [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this + parameter enables the feature at boot time. In + default, it is disabled. We can avoid allocating huge + chunk of memory for debug pagealloc if we don't enable + it at boot time and the system will work mostly same + with the kernel built without CONFIG_DEBUG_PAGEALLOC. + on: enable the feature + + debugpat [X86] Enable PAT debugging + + decnet.addr= [HW,NET] + Format: <area>[,<node>] + See also Documentation/networking/decnet.txt. + + default_hugepagesz= + [same as hugepagesz=] The size of the default + HugeTLB page size. This is the size represented by + the legacy /proc/ hugepages APIs, used for SHM, and + default size when mounting hugetlbfs filesystems. + Defaults to the default architecture's huge page size + if not specified. + + dhash_entries= [KNL] + Set number of hash buckets for dentry cache. + + disable_1tb_segments [PPC] + Disables the use of 1TB hash page table segments. This + causes the kernel to fall back to 256MB segments which + can be useful when debugging issues that require an SLB + miss to occur. + + disable= [IPV6] + See Documentation/networking/ipv6.txt. + + disable_radix [PPC] + Disable RADIX MMU mode on POWER9 + + disable_cpu_apicid= [X86,APIC,SMP] + Format: <int> + The number of initial APIC ID for the + corresponding CPU to be disabled at boot, + mostly used for the kdump 2nd kernel to + disable BSP to wake up multiple CPUs without + causing system reset or hang due to sending + INIT from AP to BSP. + + disable_ddw [PPC/PSERIES] + Disable Dynamic DMA Window support. Use this if + to workaround buggy firmware. + + disable_ipv6= [IPV6] + See Documentation/networking/ipv6.txt. + + disable_mtrr_cleanup [X86] + The kernel tries to adjust MTRR layout from continuous + to discrete, to make X server driver able to add WB + entry later. This parameter disables that. + + disable_mtrr_trim [X86, Intel and AMD only] + By default the kernel will trim any uncacheable + memory out of your available memory pool based on + MTRR settings. This parameter disables that behavior, + possibly causing your machine to run very slowly. + + disable_timer_pin_1 [X86] + Disable PIN 1 of APIC timer + Can be useful to work around chipset bugs. + + dis_ucode_ldr [X86] Disable the microcode loader. + + dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, + this option disables the debugging code at boot. + + dma_debug_entries=<number> + This option allows to tune the number of preallocated + entries for DMA-API debugging code. One entry is + required per DMA-API allocation. Use this if the + DMA-API debugging code disables itself because the + architectural default is too low. + + dma_debug_driver=<driver_name> + With this option the DMA-API debugging driver + filter feature can be enabled at boot time. Just + pass the driver to filter for as the parameter. + The filter can be disabled or changed to another + driver later using sysfs. + + drm_kms_helper.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] + Broken monitors, graphic adapters, KVMs and EDIDless + panels may send no or incorrect EDID data sets. + This parameter allows to specify an EDID data sets + in the /lib/firmware directory that are used instead. + Generic built-in EDID data sets are used, if one of + edid/1024x768.bin, edid/1280x1024.bin, + edid/1680x1050.bin, or edid/1920x1080.bin is given + and no file with the same name exists. Details and + instructions how to build your own EDID data are + available in Documentation/EDID/HOWTO.txt. An EDID + data set will only be used for a particular connector, + if its name and a colon are prepended to the EDID + name. Each connector may use a unique EDID data + set by separating the files with a comma. An EDID + data set with no connector name will be used for + any connectors not explicitly specified. + + dscc4.setup= [NET] + + dump_apple_properties [X86] + Dump name and content of EFI device properties on + x86 Macs. Useful for driver authors to determine + what data is available or for reverse-engineering. + + dyndbg[="val"] [KNL,DYNAMIC_DEBUG] + module.dyndbg[="val"] + Enable debug messages at boot time. See + Documentation/dynamic-debug-howto.txt for details. + + nompx [X86] Disables Intel Memory Protection Extensions. + See Documentation/x86/intel_mpx.txt for more + information about the feature. + + nopku [X86] Disable Memory Protection Keys CPU feature found + in some Intel CPUs. + + module.async_probe [KNL] + Enable asynchronous probe on this module. + + early_ioremap_debug [KNL] + Enable debug messages in early_ioremap support. This + is useful for tracking down temporary early mappings + which are not unmapped. + + earlycon= [KNL] Output early console device and options. + + When used with no options, the early console is + determined by the stdout-path property in device + tree's chosen node. + + cdns,<addr>[,options] + Start an early, polled-mode console on a Cadence + (xuartps) serial port at the specified address. Only + supported option is baud rate. If baud rate is not + specified, the serial port must already be setup and + configured. + + uart[8250],io,<addr>[,options] + uart[8250],mmio,<addr>[,options] + uart[8250],mmio32,<addr>[,options] + uart[8250],mmio32be,<addr>[,options] + uart[8250],0x<addr>[,options] + Start an early, polled-mode console on the 8250/16550 + UART at the specified I/O port or MMIO address. + MMIO inter-register address stride is either 8-bit + (mmio) or 32-bit (mmio32 or mmio32be). + If none of [io|mmio|mmio32|mmio32be], <addr> is assumed + to be equivalent to 'mmio'. 'options' are specified + in the same format described for "console=ttyS<n>"; if + unspecified, the h/w is not initialized. + + pl011,<addr> + pl011,mmio32,<addr> + Start an early, polled-mode console on a pl011 serial + port at the specified address. The pl011 serial port + must already be setup and configured. Options are not + yet supported. If 'mmio32' is specified, then only + the driver will use only 32-bit accessors to read/write + the device registers. + + meson,<addr> + Start an early, polled-mode console on a meson serial + port at the specified address. The serial port must + already be setup and configured. Options are not yet + supported. + + msm_serial,<addr> + Start an early, polled-mode console on an msm serial + port at the specified address. The serial port + must already be setup and configured. Options are not + yet supported. + + msm_serial_dm,<addr> + Start an early, polled-mode console on an msm serial + dm port at the specified address. The serial port + must already be setup and configured. Options are not + yet supported. + + smh Use ARM semihosting calls for early console. + + s3c2410,<addr> + s3c2412,<addr> + s3c2440,<addr> + s3c6400,<addr> + s5pv210,<addr> + exynos4210,<addr> + Use early console provided by serial driver available + on Samsung SoCs, requires selecting proper type and + a correct base address of the selected UART port. The + serial port must already be setup and configured. + Options are not yet supported. + + lpuart,<addr> + lpuart32,<addr> + Use early console provided by Freescale LP UART driver + found on Freescale Vybrid and QorIQ LS1021A processors. + A valid base address must be provided, and the serial + port must already be setup and configured. + + armada3700_uart,<addr> + Start an early, polled-mode console on the + Armada 3700 serial port at the specified + address. The serial port must already be setup + and configured. Options are not yet supported. + + earlyprintk= [X86,SH,BLACKFIN,ARM,M68k] + earlyprintk=vga + earlyprintk=efi + earlyprintk=xen + earlyprintk=serial[,ttySn[,baudrate]] + earlyprintk=serial[,0x...[,baudrate]] + earlyprintk=ttySn[,baudrate] + earlyprintk=dbgp[debugController#] + earlyprintk=pciserial,bus:device.function[,baudrate] + + earlyprintk is useful when the kernel crashes before + the normal console is initialized. It is not enabled by + default because it has some cosmetic problems. + + Append ",keep" to not disable it when the real console + takes over. + + Only one of vga, efi, serial, or usb debug port can + be used at a time. + + Currently only ttyS0 and ttyS1 may be specified by + name. Other I/O ports may be explicitly specified + on some architectures (x86 and arm at least) by + replacing ttySn with an I/O port address, like this: + earlyprintk=serial,0x1008,115200 + You can find the port for a given device in + /proc/tty/driver/serial: + 2: uart:ST16650V2 port:00001008 irq:18 ... + + Interaction with the standard serial driver is not + very good. + + The VGA and EFI output is eventually overwritten by + the real console. + + The xen output can only be used by Xen PV guests. + + edac_report= [HW,EDAC] Control how to report EDAC event + Format: {"on" | "off" | "force"} + on: enable EDAC to report H/W event. May be overridden + by other higher priority error reporting module. + off: disable H/W event reporting through EDAC. + force: enforce the use of EDAC to report H/W event. + default: on. + + ekgdboc= [X86,KGDB] Allow early kernel console debugging + ekgdboc=kbd + + This is designed to be used in conjunction with + the boot argument: earlyprintk=vga + + edd= [EDD] + Format: {"off" | "on" | "skip[mbr]"} + + efi= [EFI] + Format: { "old_map", "nochunk", "noruntime", "debug" } + old_map [X86-64]: switch to the old ioremap-based EFI + runtime services mapping. 32-bit still uses this one by + default. + nochunk: disable reading files in "chunks" in the EFI + boot stub, as chunking can cause problems with some + firmware implementations. + noruntime : disable EFI runtime services support + debug: enable misc debug output + + efi_no_storage_paranoia [EFI; X86] + Using this parameter you can use more than 50% of + your efi variable storage. Use this parameter only if + you are really sure that your UEFI does sane gc and + fulfills the spec otherwise your board may brick. + + efi_fake_mem= nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86] + Add arbitrary attribute to specific memory range by + updating original EFI memory map. + Region of memory which aa attribute is added to is + from ss to ss+nn. + If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000 + is specified, EFI_MEMORY_MORE_RELIABLE(0x10000) + attribute is added to range 0x100000000-0x180000000 and + 0x10a0000000-0x1120000000. + + Using this parameter you can do debugging of EFI memmap + related feature. For example, you can do debugging of + Address Range Mirroring feature even if your box + doesn't support it. + + efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT + that is to be dynamically loaded by Linux. If there are + multiple variables with the same name but with different + vendor GUIDs, all of them will be loaded. See + Documentation/acpi/ssdt-overlays.txt for details. + + + eisa_irq_edge= [PARISC,HW] + See header of drivers/parisc/eisa.c. + + elanfreq= [X86-32] + See comment before function elanfreq_setup() in + arch/x86/kernel/cpu/cpufreq/elanfreq.c. + + elevator= [IOSCHED] + Format: {"cfq" | "deadline" | "noop"} + See Documentation/block/cfq-iosched.txt and + Documentation/block/deadline-iosched.txt for details. + + elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390] + Specifies physical address of start of kernel core + image elf header and optionally the size. Generally + kexec loader will pass this option to capture kernel. + See Documentation/kdump/kdump.txt for details. + + enable_mtrr_cleanup [X86] + The kernel tries to adjust MTRR layout from continuous + to discrete, to make X server driver able to add WB + entry later. This parameter enables that. + + enable_timer_pin_1 [X86] + Enable PIN 1 of APIC timer + Can be useful to work around chipset bugs + (in particular on some ATI chipsets). + The kernel tries to set a reasonable default. + + enforcing [SELINUX] Set initial enforcing status. + Format: {"0" | "1"} + See security/selinux/Kconfig help text. + 0 -- permissive (log only, no denials). + 1 -- enforcing (deny and log). + Default value is 0. + Value can be changed at runtime via /selinux/enforce. + + erst_disable [ACPI] + Disable Error Record Serialization Table (ERST) + support. + + ether= [HW,NET] Ethernet cards parameters + This option is obsoleted by the "netdev=" option, which + has equivalent usage. See its documentation for details. + + evm= [EVM] + Format: { "fix" } + Permit 'security.evm' to be updated regardless of + current integrity status. + + failslab= + fail_page_alloc= + fail_make_request=[KNL] + General fault injection mechanism. + Format: <interval>,<probability>,<space>,<times> + See also Documentation/fault-injection/. + + floppy= [HW] + See Documentation/blockdev/floppy.txt. + + force_pal_cache_flush + [IA-64] Avoid check_sal_cache_flush which may hang on + buggy SAL_CACHE_FLUSH implementations. Using this + parameter will force ia64_sal_cache_flush to call + ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. + + forcepae [X86-32] + Forcefully enable Physical Address Extension (PAE). + Many Pentium M systems disable PAE but may have a + functionally usable PAE implementation. + Warning: use of this parameter will taint the kernel + and may cause unknown problems. + + ftrace=[tracer] + [FTRACE] will set and start the specified tracer + as early as possible in order to facilitate early + boot debugging. + + ftrace_dump_on_oops[=orig_cpu] + [FTRACE] will dump the trace buffers on oops. + If no parameter is passed, ftrace will dump + buffers of all CPUs, but if you pass orig_cpu, it will + dump only the buffer of the CPU that triggered the + oops. + + ftrace_filter=[function-list] + [FTRACE] Limit the functions traced by the function + tracer at boot up. function-list is a comma separated + list of functions. This list can be changed at run + time by the set_ftrace_filter file in the debugfs + tracing directory. + + ftrace_notrace=[function-list] + [FTRACE] Do not trace the functions specified in + function-list. This list can be changed at run time + by the set_ftrace_notrace file in the debugfs + tracing directory. + + ftrace_graph_filter=[function-list] + [FTRACE] Limit the top level callers functions traced + by the function graph tracer at boot up. + function-list is a comma separated list of functions + that can be changed at run time by the + set_graph_function file in the debugfs tracing directory. + + ftrace_graph_notrace=[function-list] + [FTRACE] Do not trace from the functions specified in + function-list. This list is a comma separated list of + functions that can be changed at run time by the + set_graph_notrace file in the debugfs tracing directory. + + gamecon.map[2|3]= + [HW,JOY] Multisystem joystick and NES/SNES/PSX pad + support via parallel port (up to 5 devices per port) + Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> + See also Documentation/input/joystick-parport.txt + + gamma= [HW,DRM] + + gart_fix_e820= [X86_64] disable the fix e820 for K8 GART + Format: off | on + default: on + + gcov_persist= [GCOV] When non-zero (default), profiling data for + kernel modules is saved and remains accessible via + debugfs, even when the module is unloaded/reloaded. + When zero, profiling data is discarded and associated + debugfs files are removed at module unload time. + + gpt [EFI] Forces disk with valid GPT signature but + invalid Protective MBR to be treated as GPT. If the + primary GPT is corrupted, it enables the backup/alternate + GPT to be used instead. + + grcan.enable0= [HW] Configuration of physical interface 0. Determines + the "Enable 0" bit of the configuration register. + Format: 0 | 1 + Default: 0 + grcan.enable1= [HW] Configuration of physical interface 1. Determines + the "Enable 0" bit of the configuration register. + Format: 0 | 1 + Default: 0 + grcan.select= [HW] Select which physical interface to use. + Format: 0 | 1 + Default: 0 + grcan.txsize= [HW] Sets the size of the tx buffer. + Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0. + Default: 1024 + grcan.rxsize= [HW] Sets the size of the rx buffer. + Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. + Default: 1024 + + gpio-mockup.gpio_mockup_ranges + [HW] Sets the ranges of gpiochip of for this device. + Format: <start1>,<end1>,<start2>,<end2>... + + hardlockup_all_cpu_backtrace= + [KNL] Should the hard-lockup detector generate + backtraces on all cpus. + Format: <integer> + + hashdist= [KNL,NUMA] Large hashes allocated during boot + are distributed across NUMA nodes. Defaults on + for 64-bit NUMA, off otherwise. + Format: 0 | 1 (for off | on) + + hcl= [IA-64] SGI's Hardware Graph compatibility layer + + hd= [EIDE] (E)IDE hard drive subsystem geometry + Format: <cyl>,<head>,<sect> + + hest_disable [ACPI] + Disable Hardware Error Source Table (HEST) support; + corresponding firmware-first mode error processing + logic will be disabled. + + highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact + size of <nn>. This works even on boxes that have no + highmem otherwise. This also works to reduce highmem + size on bigger boxes. + + highres= [KNL] Enable/disable high resolution timer mode. + Valid parameters: "on", "off" + Default: "on" + + hisax= [HW,ISDN] + See Documentation/isdn/README.HiSax. + + hlt [BUGS=ARM,SH] + + hpet= [X86-32,HPET] option to control HPET usage + Format: { enable (default) | disable | force | + verbose } + disable: disable HPET and use PIT instead + force: allow force enabled of undocumented chips (ICH4, + VIA, nVidia) + verbose: show contents of HPET registers during setup + + hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET + registers. Default set by CONFIG_HPET_MMAP_DEFAULT. + + hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. + hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. + On x86-64 and powerpc, this option can be specified + multiple times interleaved with hugepages= to reserve + huge pages of different sizes. Valid pages sizes on + x86-64 are 2M (when the CPU supports "pse") and 1G + (when the CPU supports the "pdpe1gb" cpuinfo flag). + + hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) + terminal devices. Valid values: 0..8 + hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. + If specified, z/VM IUCV HVC accepts connections + from listed z/VM user IDs only. + + hwthread_map= [METAG] Comma-separated list of Linux cpu id to + hardware thread id mappings. + Format: <cpu>:<hwthread> + + keep_bootcon [KNL] + Do not unregister boot console at start. This is only + useful for debugging when something happens in the window + between unregistering the boot console and initializing + the real console. + + i2c_bus= [HW] Override the default board specific I2C bus speed + or register an additional I2C bus that is not + registered from board initialization code. + Format: + <bus_id>,<clkrate> + + i8042.debug [HW] Toggle i8042 debug mode + i8042.unmask_kbd_data + [HW] Enable printing of interrupt data from the KBD port + (disabled by default, and as a pre-condition + requires that i8042.debug=1 be enabled) + i8042.direct [HW] Put keyboard port into non-translated mode + i8042.dumbkbd [HW] Pretend that controller can only read data from + keyboard and cannot control its state + (Don't attempt to blink the leds) + i8042.noaux [HW] Don't check for auxiliary (== mouse) port + i8042.nokbd [HW] Don't check/create keyboard port + i8042.noloop [HW] Disable the AUX Loopback command while probing + for the AUX port + i8042.nomux [HW] Don't check presence of an active multiplexing + controller + i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX + controllers + i8042.notimeout [HW] Ignore timeout condition signalled by controller + i8042.reset [HW] Reset the controller during init, cleanup and + suspend-to-ram transitions, only during s2r + transitions, or never reset + Format: { 1 | Y | y | 0 | N | n } + 1, Y, y: always reset controller + 0, N, n: don't ever reset controller + Default: only on s2r transitions on x86; most other + architectures force reset to be always executed + i8042.unlock [HW] Unlock (ignore) the keylock + i8042.kbdreset [HW] Reset device connected to KBD port + + i810= [HW,DRM] + + i8k.ignore_dmi [HW] Continue probing hardware even if DMI data + indicates that the driver is running on unsupported + hardware. + i8k.force [HW] Activate i8k driver even if SMM BIOS signature + does not match list of supported models. + i8k.power_status + [HW] Report power status in /proc/i8k + (disabled by default) + i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN + capability is set. + + i915.invert_brightness= + [DRM] Invert the sense of the variable that is used to + set the brightness of the panel backlight. Normally a + brightness value of 0 indicates backlight switched off, + and the maximum of the brightness value sets the backlight + to maximum brightness. If this parameter is set to 0 + (default) and the machine requires it, or this parameter + is set to 1, a brightness value of 0 sets the backlight + to maximum brightness, and the maximum of the brightness + value switches the backlight off. + -1 -- never invert brightness + 0 -- machine default + 1 -- force brightness inversion + + icn= [HW,ISDN] + Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] + + ide-core.nodma= [HW] (E)IDE subsystem + Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc + .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr + .cdrom .chs .ignore_cable are additional options + See Documentation/ide/ide.txt. + + ide-generic.probe-mask= [HW] (E)IDE subsystem + Format: <int> + Probe mask for legacy ISA IDE ports. Depending on + platform up to 6 ports are supported, enabled by + setting corresponding bits in the mask to 1. The + default value is 0x0, which has a special meaning. + On systems that have PCI, it triggers scanning the + PCI bus for the first and the second port, which + are then probed. On systems without PCI the value + of 0x0 enables probing the two first ports as if it + was 0x3. + + ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem + Claim all unknown PCI IDE storage controllers. + + idle= [X86] + Format: idle=poll, idle=halt, idle=nomwait + Poll forces a polling idle loop that can slightly + improve the performance of waking up a idle CPU, but + will use a lot of power and make the system run hot. + Not recommended. + idle=halt: Halt is forced to be used for CPU idle. + In such case C2/C3 won't be used again. + idle=nomwait: Disable mwait for CPU C-states + + ieee754= [MIPS] Select IEEE Std 754 conformance mode + Format: { strict | legacy | 2008 | relaxed } + Default: strict + + Choose which programs will be accepted for execution + based on the IEEE 754 NaN encoding(s) supported by + the FPU and the NaN encoding requested with the value + of an ELF file header flag individually set by each + binary. Hardware implementations are permitted to + support either or both of the legacy and the 2008 NaN + encoding mode. + + Available settings are as follows: + strict accept binaries that request a NaN encoding + supported by the FPU + legacy only accept legacy-NaN binaries, if supported + by the FPU + 2008 only accept 2008-NaN binaries, if supported + by the FPU + relaxed accept any binaries regardless of whether + supported by the FPU + + The FPU emulator is always able to support both NaN + encodings, so if no FPU hardware is present or it has + been disabled with 'nofpu', then the settings of + 'legacy' and '2008' strap the emulator accordingly, + 'relaxed' straps the emulator for both legacy-NaN and + 2008-NaN, whereas 'strict' enables legacy-NaN only on + legacy processors and both NaN encodings on MIPS32 or + MIPS64 CPUs. + + The setting for ABS.fmt/NEG.fmt instruction execution + mode generally follows that for the NaN encoding, + except where unsupported by hardware. + + ignore_loglevel [KNL] + Ignore loglevel setting - this will print /all/ + kernel messages to the console. Useful for debugging. + We also add it as printk module parameter, so users + could change it dynamically, usually by + /sys/module/printk/parameters/ignore_loglevel. + + ignore_rlimit_data + Ignore RLIMIT_DATA setting for data mappings, + print warning at first misuse. Can be changed via + /sys/module/kernel/parameters/ignore_rlimit_data. + + ihash_entries= [KNL] + Set number of hash buckets for inode cache. + + ima_appraise= [IMA] appraise integrity measurements + Format: { "off" | "enforce" | "fix" | "log" } + default: "enforce" + + ima_appraise_tcb [IMA] + The builtin appraise policy appraises all files + owned by uid=0. + + ima_canonical_fmt [IMA] + Use the canonical format for the binary runtime + measurements, instead of host native format. + + ima_hash= [IMA] + Format: { md5 | sha1 | rmd160 | sha256 | sha384 + | sha512 | ... } + default: "sha1" + + The list of supported hash algorithms is defined + in crypto/hash_info.h. + + ima_policy= [IMA] + The builtin measurement policy to load during IMA + setup. Specyfing "tcb" as the value, measures all + programs exec'd, files mmap'd for exec, and all files + opened with the read mode bit set by either the + effective uid (euid=0) or uid=0. + Format: "tcb" + + ima_tcb [IMA] Deprecated. Use ima_policy= instead. + Load a policy which meets the needs of the Trusted + Computing Base. This means IMA will measure all + programs exec'd, files mmap'd for exec, and all files + opened for read by uid=0. + + ima_template= [IMA] + Select one of defined IMA measurements template formats. + Formats: { "ima" | "ima-ng" | "ima-sig" } + Default: "ima-ng" + + ima_template_fmt= + [IMA] Define a custom template format. + Format: { "field1|...|fieldN" } + + ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage + Format: <min_file_size> + Set the minimal file size for using asynchronous hash. + If left unspecified, ahash usage is disabled. + + ahash performance varies for different data sizes on + different crypto accelerators. This option can be used + to achieve the best performance for a particular HW. + + ima.ahash_bufsize= [IMA] Asynchronous hash buffer size + Format: <bufsize> + Set hashing buffer size. Default: 4k. + + ahash performance varies for different chunk sizes on + different crypto accelerators. This option can be used + to achieve best performance for particular HW. + + init= [KNL] + Format: <full_path> + Run specified binary instead of /sbin/init as init + process. + + initcall_debug [KNL] Trace initcalls as they are executed. Useful + for working out where the kernel is dying during + startup. + + initcall_blacklist= [KNL] Do not execute a comma-separated list of + initcall functions. Useful for debugging built-in + modules and initcalls. + + initrd= [BOOT] Specify the location of the initial ramdisk + + init_pkru= [x86] Specify the default memory protection keys rights + register contents for all processes. 0x55555554 by + default (disallow access to all but pkey 0). Can + override in debugfs after boot. + + inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver + Format: <irq> + + int_pln_enable [x86] Enable power limit notification interrupt + + integrity_audit=[IMA] + Format: { "0" | "1" } + 0 -- basic integrity auditing messages. (Default) + 1 -- additional integrity auditing messages. + + intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option + on + Enable intel iommu driver. + off + Disable intel iommu driver. + igfx_off [Default Off] + By default, gfx is mapped as normal device. If a gfx + device has a dedicated DMAR unit, the DMAR unit is + bypassed by not enabling DMAR with this option. In + this case, gfx device will use physical address for + DMA. + forcedac [x86_64] + With this option iommu will not optimize to look + for io virtual address below 32-bit forcing dual + address cycle on pci bus for cards supporting greater + than 32-bit addressing. The default is to look + for translation below 32-bit and if not available + then look in the higher range. + strict [Default Off] + With this option on every unmap_single operation will + result in a hardware IOTLB flush operation as opposed + to batching them for performance. + sp_off [Default Off] + By default, super page will be supported if Intel IOMMU + has the capability. With this option, super page will + not be supported. + ecs_off [Default Off] + By default, extended context tables will be supported if + the hardware advertises that it has support both for the + extended tables themselves, and also PASID support. With + this option set, extended tables will not be used even + on hardware which claims to support them. + + intel_idle.max_cstate= [KNL,HW,ACPI,X86] + 0 disables intel_idle and fall back on acpi_idle. + 1 to 9 specify maximum depth of C-state. + + intel_pstate= [X86] + disable + Do not enable intel_pstate as the default + scaling driver for the supported processors + passive + Use intel_pstate as a scaling driver, but configure it + to work with generic cpufreq governors (instead of + enabling its internal governor). This mode cannot be + used along with the hardware-managed P-states (HWP) + feature. + force + Enable intel_pstate on systems that prohibit it by default + in favor of acpi-cpufreq. Forcing the intel_pstate driver + instead of acpi-cpufreq may disable platform features, such + as thermal controls and power capping, that rely on ACPI + P-States information being indicated to OSPM and therefore + should be used with caution. This option does not work with + processors that aren't supported by the intel_pstate driver + or on platforms that use pcc-cpufreq instead of acpi-cpufreq. + no_hwp + Do not enable hardware P state control (HWP) + if available. + hwp_only + Only load intel_pstate on systems which support + hardware P state control (HWP) if available. + support_acpi_ppc + Enforce ACPI _PPC performance limits. If the Fixed ACPI + Description Table, specifies preferred power management + profile as "Enterprise Server" or "Performance Server", + then this feature is turned on by default. + per_cpu_perf_limits + Allow per-logical-CPU P-State performance control limits using + cpufreq sysfs interface + + intremap= [X86-64, Intel-IOMMU] + on enable Interrupt Remapping (default) + off disable Interrupt Remapping + nosid disable Source ID checking + no_x2apic_optout + BIOS x2APIC opt-out request will be ignored + nopost disable Interrupt Posting + + iomem= Disable strict checking of access to MMIO memory + strict regions from userspace. + relaxed + + iommu= [x86] + off + force + noforce + biomerge + panic + nopanic + merge + nomerge + forcesac + soft + pt [x86, IA-64] + nobypass [PPC/POWERNV] + Disable IOMMU bypass, using IOMMU for PCI devices. + + + io7= [HW] IO7 for Marvel based alpha systems + See comment before marvel_specify_io7 in + arch/alpha/kernel/core_marvel.c. + + io_delay= [X86] I/O delay method + 0x80 + Standard port 0x80 based delay + 0xed + Alternate port 0xed based delay (needed on some systems) + udelay + Simple two microseconds delay + none + No delay + + ip= [IP_PNP] + See Documentation/filesystems/nfs/nfsroot.txt. + + irqaffinity= [SMP] Set the default irq affinity mask + The argument is a cpu list, as described above. + + irqfixup [HW] + When an interrupt is not handled search all handlers + for it. Intended to get systems with badly broken + firmware running. + + irqpoll [HW] + When an interrupt is not handled search all handlers + for it. Also check all handlers each timer + interrupt. Intended to get systems with badly broken + firmware running. + + isapnp= [ISAPNP] + Format: <RDP>,<reset>,<pci_scan>,<verbosity> + + isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. + The argument is a cpu list, as described above. + + This option can be used to specify one or more CPUs + to isolate from the general SMP balancing and scheduling + algorithms. You can move a process onto or off an + "isolated" CPU via the CPU affinity syscalls or cpuset. + <cpu number> begins at 0 and the maximum value is + "number of CPUs in system - 1". + + This option is the preferred way to isolate CPUs. The + alternative -- manually setting the CPU mask of all + tasks in the system -- can cause problems and + suboptimal load balancer performance. + + iucv= [HW,NET] + + ivrs_ioapic [HW,X86_64] + Provide an override to the IOAPIC-ID<->DEVICE-ID + mapping provided in the IVRS ACPI table. For + example, to map IOAPIC-ID decimal 10 to + PCI device 00:14.0 write the parameter as: + ivrs_ioapic[10]=00:14.0 + + ivrs_hpet [HW,X86_64] + Provide an override to the HPET-ID<->DEVICE-ID + mapping provided in the IVRS ACPI table. For + example, to map HPET-ID decimal 0 to + PCI device 00:14.0 write the parameter as: + ivrs_hpet[0]=00:14.0 + + ivrs_acpihid [HW,X86_64] + Provide an override to the ACPI-HID:UID<->DEVICE-ID + mapping provided in the IVRS ACPI table. For + example, to map UART-HID:UID AMD0020:0 to + PCI device 00:14.5 write the parameter as: + ivrs_acpihid[00:14.5]=AMD0020:0 + + js= [HW,JOY] Analog joystick + See Documentation/input/joystick.txt. + + nokaslr [KNL] + When CONFIG_RANDOMIZE_BASE is set, this disables + kernel and module base offset ASLR (Address Space + Layout Randomization). + + keepinitrd [HW,ARM] + + kernelcore= [KNL,X86,IA-64,PPC] + Format: nn[KMGTPE] | "mirror" + This parameter + specifies the amount of memory usable by the kernel + for non-movable allocations. The requested amount is + spread evenly throughout all nodes in the system. The + remaining memory in each node is used for Movable + pages. In the event, a node is too small to have both + kernelcore and Movable pages, kernelcore pages will + take priority and other nodes will have a larger number + of Movable pages. The Movable zone is used for the + allocation of pages that may be reclaimed or moved + by the page migration subsystem. This means that + HugeTLB pages may not be allocated from this zone. + Note that allocations like PTEs-from-HighMem still + use the HighMem zone if it exists, and the Normal + zone if it does not. + + Instead of specifying the amount of memory (nn[KMGTPE]), + you can specify "mirror" option. In case "mirror" + option is specified, mirrored (reliable) memory is used + for non-movable allocations and remaining memory is used + for Movable pages. nn[KMGTPE] and "mirror" are exclusive, + so you can NOT specify nn[KMGTPE] and "mirror" at the same + time. + + kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. + Format: <Controller#>[,poll interval] + The controller # is the number of the ehci usb debug + port as it is probed via PCI. The poll interval is + optional and is the number seconds in between + each poll cycle to the debug port in case you need + the functionality for interrupting the kernel with + gdb or control-c on the dbgp connection. When + not using this parameter you use sysrq-g to break into + the kernel debugger. + + kgdboc= [KGDB,HW] kgdb over consoles. + Requires a tty driver that supports console polling, + or a supported polling keyboard driver (non-usb). + Serial only format: <serial_device>[,baud] + keyboard only format: kbd + keyboard and serial format: kbd,<serial_device>[,baud] + Optional Kernel mode setting: + kms, kbd format: kms,kbd + kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] + + kgdbwait [KGDB] Stop kernel execution and enter the + kernel debugger at the earliest opportunity. + + kmac= [MIPS] korina ethernet MAC address. + Configure the RouterBoard 532 series on-chip + Ethernet adapter MAC address. + + kmemleak= [KNL] Boot-time kmemleak enable/disable + Valid arguments: on, off + Default: on + Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, + the default is off. + + kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode + Valid arguments: 0, 1, 2 + kmemcheck=0 (disabled) + kmemcheck=1 (enabled) + kmemcheck=2 (one-shot mode) + Default: 2 (one-shot mode) + + kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. + Default is 0 (don't ignore, but inject #GP) + + kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit + KVM MMU at runtime. + Default is 0 (off) + + kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM. + Default is 1 (enabled) + + kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU) + for all guests. + Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. + + kvm-intel.ept= [KVM,Intel] Disable extended page tables + (virtualized MMU) support on capable Intel chips. + Default is 1 (enabled) + + kvm-intel.emulate_invalid_guest_state= + [KVM,Intel] Enable emulation of invalid guest states + Default is 0 (disabled) + + kvm-intel.flexpriority= + [KVM,Intel] Disable FlexPriority feature (TPR shadow). + Default is 1 (enabled) + + kvm-intel.nested= + [KVM,Intel] Enable VMX nesting (nVMX). + Default is 0 (disabled) + + kvm-intel.unrestricted_guest= + [KVM,Intel] Disable unrestricted guest feature + (virtualized real and unpaged mode) on capable + Intel chips. Default is 1 (enabled) + + kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification + feature (tagged TLBs) on capable Intel chips. + Default is 1 (enabled) + + l2cr= [PPC] + + l3cr= [PPC] + + lapic [X86-32,APIC] Enable the local APIC even if BIOS + disabled it. + + lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline + value for LAPIC timer one-shot implementation. Default + back to the programmable timer unit in the LAPIC. + + lapic_timer_c2_ok [X86,APIC] trust the local apic timer + in C2 power state. + + libata.dma= [LIBATA] DMA control + libata.dma=0 Disable all PATA and SATA DMA + libata.dma=1 PATA and SATA Disk DMA only + libata.dma=2 ATAPI (CDROM) DMA only + libata.dma=4 Compact Flash DMA only + Combinations also work, so libata.dma=3 enables DMA + for disks and CDROMs, but not CFs. + + libata.ignore_hpa= [LIBATA] Ignore HPA limit + libata.ignore_hpa=0 keep BIOS limits (default) + libata.ignore_hpa=1 ignore limits, using full disk + + libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume + when set. + Format: <int> + + libata.force= [LIBATA] Force configurations. The format is comma + separated list of "[ID:]VAL" where ID is + PORT[.DEVICE]. PORT and DEVICE are decimal numbers + matching port, link or device. Basically, it matches + the ATA ID string printed on console by libata. If + the whole ID part is omitted, the last PORT and DEVICE + values are used. If ID hasn't been specified yet, the + configuration applies to all ports, links and devices. + + If only DEVICE is omitted, the parameter applies to + the port and all links and devices behind it. DEVICE + number of 0 either selects the first device or the + first fan-out link behind PMP device. It does not + select the host link. DEVICE number of 15 selects the + host link and device attached to it. + + The VAL specifies the configuration to force. As long + as there's no ambiguity shortcut notation is allowed. + For example, both 1.5 and 1.5G would work for 1.5Gbps. + The following configurations can be forced. + + * Cable type: 40c, 80c, short40c, unk, ign or sata. + Any ID with matching PORT is used. + + * SATA link speed limit: 1.5Gbps or 3.0Gbps. + + * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. + udma[/][16,25,33,44,66,100,133] notation is also + allowed. + + * [no]ncq: Turn on or off NCQ. + + * [no]ncqtrim: Turn off queued DSM TRIM. + + * nohrst, nosrst, norst: suppress hard, soft + and both resets. + + * rstonce: only attempt one reset during + hot-unplug link recovery + + * dump_id: dump IDENTIFY data. + + * atapi_dmadir: Enable ATAPI DMADIR bridge support + + * disable: Disable this device. + + If there are multiple matching configurations changing + the same attribute, the last one is used. + + memblock=debug [KNL] Enable memblock debug messages. + + load_ramdisk= [RAM] List of ramdisks to load from floppy + See Documentation/blockdev/ramdisk.txt. + + lockd.nlm_grace_period=P [NFS] Assign grace period. + Format: <integer> + + lockd.nlm_tcpport=N [NFS] Assign TCP port. + Format: <integer> + + lockd.nlm_timeout=T [NFS] Assign timeout value. + Format: <integer> + + lockd.nlm_udpport=M [NFS] Assign UDP port. + Format: <integer> + + locktorture.nreaders_stress= [KNL] + Set the number of locking read-acquisition kthreads. + Defaults to being automatically set based on the + number of online CPUs. + + locktorture.nwriters_stress= [KNL] + Set the number of locking write-acquisition kthreads. + + locktorture.onoff_holdoff= [KNL] + Set time (s) after boot for CPU-hotplug testing. + + locktorture.onoff_interval= [KNL] + Set time (s) between CPU-hotplug operations, or + zero to disable CPU-hotplug testing. + + locktorture.shuffle_interval= [KNL] + Set task-shuffle interval (jiffies). Shuffling + tasks allows some CPUs to go into dyntick-idle + mode during the locktorture test. + + locktorture.shutdown_secs= [KNL] + Set time (s) after boot system shutdown. This + is useful for hands-off automated testing. + + locktorture.stat_interval= [KNL] + Time (s) between statistics printk()s. + + locktorture.stutter= [KNL] + Time (s) to stutter testing, for example, + specifying five seconds causes the test to run for + five seconds, wait for five seconds, and so on. + This tests the locking primitive's ability to + transition abruptly to and from idle. + + locktorture.torture_runnable= [BOOT] + Start locktorture running at boot time. + + locktorture.torture_type= [KNL] + Specify the locking implementation to test. + + locktorture.verbose= [KNL] + Enable additional printk() statements. + + logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver + Format: <irq> + + loglevel= All Kernel Messages with a loglevel smaller than the + console loglevel will be printed to the console. It can + also be changed with klogd or other programs. The + loglevels are defined as follows: + + 0 (KERN_EMERG) system is unusable + 1 (KERN_ALERT) action must be taken immediately + 2 (KERN_CRIT) critical conditions + 3 (KERN_ERR) error conditions + 4 (KERN_WARNING) warning conditions + 5 (KERN_NOTICE) normal but significant condition + 6 (KERN_INFO) informational + 7 (KERN_DEBUG) debug-level messages + + log_buf_len=n[KMG] Sets the size of the printk ring buffer, + in bytes. n must be a power of two and greater + than the minimal size. The minimal size is defined + by LOG_BUF_SHIFT kernel config parameter. There is + also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter + that allows to increase the default size depending on + the number of CPUs. See init/Kconfig for more details. + + logo.nologo [FB] Disables display of the built-in Linux logo. + This may be used to provide more screen space for + kernel log messages and is useful when debugging + kernel boot problems. + + lp=0 [LP] Specify parallel ports to use, e.g, + lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses + lp=reset first parallel port). 'lp=0' disables the + lp=auto printer driver. 'lp=reset' (which can be + specified in addition to the ports) causes + attached printers to be reset. Using + lp=port1,port2,... specifies the parallel ports + to associate lp devices with, starting with + lp0. A port specification may be 'none' to skip + that lp device, or a parport name such as + 'parport0'. Specifying 'lp=auto' instead of a + port specification list means that device IDs + from each port should be examined, to see if + an IEEE 1284-compliant printer is attached; if + so, the driver will manage that printer. + See also header of drivers/char/lp.c. + + lpj=n [KNL] + Sets loops_per_jiffy to given constant, thus avoiding + time-consuming boot-time autodetection (up to 250 ms per + CPU). 0 enables autodetection (default). To determine + the correct value for your kernel, boot with normal + autodetection and see what value is printed. Note that + on SMP systems the preset will be applied to all CPUs, + which is likely to cause problems if your CPUs need + significantly divergent settings. An incorrect value + will cause delays in the kernel to be wrong, leading to + unpredictable I/O errors and other breakage. Although + unlikely, in the extreme case this might damage your + hardware. + + ltpc= [NET] + Format: <io>,<irq>,<dma> + + machvec= [IA-64] Force the use of a particular machine-vector + (machvec) in a generic kernel. + Example: machvec=hpzx1_swiotlb + + machtype= [Loongson] Share the same kernel image file between different + yeeloong laptop. + Example: machtype=lemote-yeeloong-2f-7inch + + max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater + than or equal to this physical address is ignored. + + maxcpus= [SMP] Maximum number of processors that an SMP kernel + will bring up during bootup. maxcpus=n : n >= 0 limits + the kernel to bring up 'n' processors. Surely after + bootup you can bring up the other plugged cpu by executing + "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus + only takes effect during system bootup. + While n=0 is a special case, it is equivalent to "nosmp", + which also disables the IO APIC. + + max_loop= [LOOP] The number of loop block devices that get + (loop.max_loop) unconditionally pre-created at init time. The default + number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead + of statically allocating a predefined number, loop + devices can be requested on-demand with the + /dev/loop-control interface. + + mce [X86-32] Machine Check Exception + + mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt + + md= [HW] RAID subsystems devices and level + See Documentation/admin-guide/md.rst. + + mdacon= [MDA] + Format: <first>,<last> + Specifies range of consoles to be captured by the MDA. + + mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory + Amount of memory to be used when the kernel is not able + to see the whole system memory or for test. + [X86] Work as limiting max address. Use together + with memmap= to avoid physical address space collisions. + Without memmap= PCI devices could be placed at addresses + belonging to unused RAM. + + mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel + memory. + + memchunk=nn[KMG] + [KNL,SH] Allow user to override the default size for + per-device physically contiguous DMA buffers. + + memhp_default_state=online/offline + [KNL] Set the initial state for the memory hotplug + onlining policy. If not specified, the default value is + set according to the + CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config + option. + See Documentation/memory-hotplug.txt. + + memmap=exactmap [KNL,X86] Enable setting of an exact + E820 memory map, as specified by the user. + Such memmap=exactmap lines can be constructed based on + BIOS output or other requirements. See the memmap=nn@ss + option description. + + memmap=nn[KMG]@ss[KMG] + [KNL] Force usage of a specific region of memory. + Region of memory to be used is from ss to ss+nn. + + memmap=nn[KMG]#ss[KMG] + [KNL,ACPI] Mark specific memory as ACPI data. + Region of memory to be marked is from ss to ss+nn. + + memmap=nn[KMG]$ss[KMG] + [KNL,ACPI] Mark specific memory as reserved. + Region of memory to be reserved is from ss to ss+nn. + Example: Exclude memory from 0x18690000-0x1869ffff + memmap=64K$0x18690000 + or + memmap=0x10000$0x18690000 + + memmap=nn[KMG]!ss[KMG] + [KNL,X86] Mark specific memory as protected. + Region of memory to be used, from ss to ss+nn. + The memory region may be marked as e820 type 12 (0xc) + and is NVDIMM or ADR memory. + + memory_corruption_check=0/1 [X86] + Some BIOSes seem to corrupt the first 64k of + memory when doing things like suspend/resume. + Setting this option will scan the memory + looking for corruption. Enabling this will + both detect corruption and prevent the kernel + from using the memory being corrupted. + However, its intended as a diagnostic tool; if + repeatable BIOS-originated corruption always + affects the same memory, you can use memmap= + to prevent the kernel from using that memory. + + memory_corruption_check_size=size [X86] + By default it checks for corruption in the low + 64k, making this memory unavailable for normal + use. Use this parameter to scan for + corruption in more or less memory. + + memory_corruption_check_period=seconds [X86] + By default it checks for corruption every 60 + seconds. Use this parameter to check at some + other rate. 0 disables periodic checking. + + memtest= [KNL,X86,ARM] Enable memtest + Format: <integer> + default : 0 <disable> + Specifies the number of memtest passes to be + performed. Each pass selects another test + pattern from a given set of patterns. Memtest + fills the memory with this pattern, validates + memory contents and reserves bad memory + regions that are detected. + + mem_sleep_default= [SUSPEND] Default system suspend mode: + s2idle - Suspend-To-Idle + shallow - Power-On Suspend or equivalent (if supported) + deep - Suspend-To-RAM or equivalent (if supported) + See Documentation/power/states.txt. + + meye.*= [HW] Set MotionEye Camera parameters + See Documentation/video4linux/meye.txt. + + mfgpt_irq= [IA-32] Specify the IRQ to use for the + Multi-Function General Purpose Timers on AMD Geode + platforms. + + mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when + the BIOS has incorrectly applied a workaround. TinyBIOS + version 0.98 is known to be affected, 0.99 fixes the + problem by letting the user disable the workaround. + + mga= [HW,DRM] + + min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this + physical address is ignored. + + mini2440= [ARM,HW,KNL] + Format:[0..2][b][c][t] + Default: "0tb" + MINI2440 configuration specification: + 0 - The attached screen is the 3.5" TFT + 1 - The attached screen is the 7" TFT + 2 - The VGA Shield is attached (1024x768) + Leaving out the screen size parameter will not load + the TFT driver, and the framebuffer will be left + unconfigured. + b - Enable backlight. The TFT backlight pin will be + linked to the kernel VESA blanking code and a GPIO + LED. This parameter is not necessary when using the + VGA shield. + c - Enable the s3c camera interface. + t - Reserved for enabling touchscreen support. The + touchscreen support is not enabled in the mainstream + kernel as of 2.6.30, a preliminary port can be found + in the "bleeding edge" mini2440 support kernel at + http://repo.or.cz/w/linux-2.6/mini2440.git + + mminit_loglevel= + [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this + parameter allows control of the logging verbosity for + the additional memory initialisation checks. A value + of 0 disables mminit logging and a level of 4 will + log everything. Information is printed at KERN_DEBUG + so loglevel=8 may also need to be specified. + + module.sig_enforce + [KNL] When CONFIG_MODULE_SIG is set, this means that + modules without (valid) signatures will fail to load. + Note that if CONFIG_MODULE_SIG_FORCE is set, that + is always true, so this option does nothing. + + module_blacklist= [KNL] Do not load a comma-separated list of + modules. Useful for debugging problem modules. + + mousedev.tap_time= + [MOUSE] Maximum time between finger touching and + leaving touchpad surface for touch to be considered + a tap and be reported as a left button click (for + touchpads working in absolute mode only). + Format: <msecs> + mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices + reporting absolute coordinates, such as tablets + mousedev.yres= [MOUSE] Vertical screen resolution, used for devices + reporting absolute coordinates, such as tablets + + movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter + is similar to kernelcore except it specifies the + amount of memory used for migratable allocations. + If both kernelcore and movablecore is specified, + then kernelcore will be at *least* the specified + value but may be more. If movablecore on its own + is specified, the administrator must be careful + that the amount of memory usable for all allocations + is not too small. + + movable_node [KNL] Boot-time switch to enable the effects + of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details. + + MTD_Partition= [MTD] + Format: <name>,<region-number>,<size>,<offset> + + MTD_Region= [MTD] Format: + <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] + + mtdparts= [MTD] + See drivers/mtd/cmdlinepart.c. + + multitce=off [PPC] This parameter disables the use of the pSeries + firmware feature for updating multiple TCE entries + at a time. + + onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration + + Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] + + boundary - index of last SLC block on Flex-OneNAND. + The remaining blocks are configured as MLC blocks. + lock - Configure if Flex-OneNAND boundary should be locked. + Once locked, the boundary cannot be changed. + 1 indicates lock status, 0 indicates unlock status. + + mtdset= [ARM] + ARM/S3C2412 JIVE boot control + + See arch/arm/mach-s3c2412/mach-jive.c + + mtouchusb.raw_coordinates= + [HW] Make the MicroTouch USB driver use raw coordinates + ('y', default) or cooked coordinates ('n') + + mtrr_chunk_size=nn[KMG] [X86] + used for mtrr cleanup. It is largest continuous chunk + that could hold holes aka. UC entries. + + mtrr_gran_size=nn[KMG] [X86] + Used for mtrr cleanup. It is granularity of mtrr block. + Default is 1. + Large value could prevent small alignment from + using up MTRRs. + + mtrr_spare_reg_nr=n [X86] + Format: <integer> + Range: 0,7 : spare reg number + Default : 1 + Used for mtrr cleanup. It is spare mtrr entries number. + Set to 2 or more if your graphical card needs more. + + n2= [NET] SDL Inc. RISCom/N2 synchronous serial card + + netdev= [NET] Network devices parameters + Format: <irq>,<io>,<mem_start>,<mem_end>,<name> + Note that mem_start is often overloaded to mean + something different and driver-specific. + This usage is only documented in each driver source + file if at all. + + nf_conntrack.acct= + [NETFILTER] Enable connection tracking flow accounting + 0 to disable accounting + 1 to enable accounting + Default value is 0. + + nfsaddrs= [NFS] Deprecated. Use ip= instead. + See Documentation/filesystems/nfs/nfsroot.txt. + + nfsroot= [NFS] nfs root filesystem for disk-less boxes. + See Documentation/filesystems/nfs/nfsroot.txt. + + nfsrootdebug [NFS] enable nfsroot debugging messages. + See Documentation/filesystems/nfs/nfsroot.txt. + + nfs.callback_nr_threads= + [NFSv4] set the total number of threads that the + NFS client will assign to service NFSv4 callback + requests. + + nfs.callback_tcpport= + [NFS] set the TCP port on which the NFSv4 callback + channel should listen. + + nfs.cache_getent= + [NFS] sets the pathname to the program which is used + to update the NFS client cache entries. + + nfs.cache_getent_timeout= + [NFS] sets the timeout after which an attempt to + update a cache entry is deemed to have failed. + + nfs.idmap_cache_timeout= + [NFS] set the maximum lifetime for idmapper cache + entries. + + nfs.enable_ino64= + [NFS] enable 64-bit inode numbers. + If zero, the NFS client will fake up a 32-bit inode + number for the readdir() and stat() syscalls instead + of returning the full 64-bit number. + The default is to return 64-bit inode numbers. + + nfs.max_session_cb_slots= + [NFSv4.1] Sets the maximum number of session + slots the client will assign to the callback + channel. This determines the maximum number of + callbacks the client will process in parallel for + a particular server. + + nfs.max_session_slots= + [NFSv4.1] Sets the maximum number of session slots + the client will attempt to negotiate with the server. + This limits the number of simultaneous RPC requests + that the client can send to the NFSv4.1 server. + Note that there is little point in setting this + value higher than the max_tcp_slot_table_limit. + + nfs.nfs4_disable_idmapping= + [NFSv4] When set to the default of '1', this option + ensures that both the RPC level authentication + scheme and the NFS level operations agree to use + numeric uids/gids if the mount is using the + 'sec=sys' security flavour. In effect it is + disabling idmapping, which can make migration from + legacy NFSv2/v3 systems to NFSv4 easier. + Servers that do not support this mode of operation + will be autodetected by the client, and it will fall + back to using the idmapper. + To turn off this behaviour, set the value to '0'. + nfs.nfs4_unique_id= + [NFS4] Specify an additional fixed unique ident- + ification string that NFSv4 clients can insert into + their nfs_client_id4 string. This is typically a + UUID that is generated at system install time. + + nfs.send_implementation_id = + [NFSv4.1] Send client implementation identification + information in exchange_id requests. + If zero, no implementation identification information + will be sent. + The default is to send the implementation identification + information. + + nfs.recover_lost_locks = + [NFSv4] Attempt to recover locks that were lost due + to a lease timeout on the server. Please note that + doing this risks data corruption, since there are + no guarantees that the file will remain unchanged + after the locks are lost. + If you want to enable the kernel legacy behaviour of + attempting to recover these locks, then set this + parameter to '1'. + The default parameter value of '0' causes the kernel + not to attempt recovery of lost locks. + + nfs4.layoutstats_timer = + [NFSv4.2] Change the rate at which the kernel sends + layoutstats to the pNFS metadata server. + + Setting this to value to 0 causes the kernel to use + whatever value is the default set by the layout + driver. A non-zero value sets the minimum interval + in seconds between layoutstats transmissions. + + nfsd.nfs4_disable_idmapping= + [NFSv4] When set to the default of '1', the NFSv4 + server will return only numeric uids and gids to + clients using auth_sys, and will accept numeric uids + and gids from such clients. This is intended to ease + migration from NFSv2/v3. + + objlayoutdriver.osd_login_prog= + [NFS] [OBJLAYOUT] sets the pathname to the program which + is used to automatically discover and login into new + osd-targets. Please see: + Documentation/filesystems/pnfs.txt for more explanations + + nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take + when a NMI is triggered. + Format: [state][,regs][,debounce][,die] + + nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels + Format: [panic,][nopanic,][num] + Valid num: 0 or 1 + 0 - turn hardlockup detector in nmi_watchdog off + 1 - turn hardlockup detector in nmi_watchdog on + When panic is specified, panic when an NMI watchdog + timeout occurs (or 'nopanic' to override the opposite + default). To disable both hard and soft lockup detectors, + please see 'nowatchdog'. + This is useful when you use a panic=... timeout and + need the box quickly up again. + + netpoll.carrier_timeout= + [NET] Specifies amount of time (in seconds) that + netpoll should wait for a carrier. By default netpoll + waits 4 seconds. + + no387 [BUGS=X86-32] Tells the kernel to use the 387 maths + emulation library even if a 387 maths coprocessor + is present. + + no_console_suspend + [HW] Never suspend the console + Disable suspending of consoles during suspend and + hibernate operations. Once disabled, debugging + messages can reach various consoles while the rest + of the system is being put to sleep (ie, while + debugging driver suspend/resume hooks). This may + not work reliably with all consoles, but is known + to work with serial and VGA consoles. + To facilitate more flexible debugging, we also add + console_suspend, a printk module parameter to control + it. Users could use console_suspend (usually + /sys/module/printk/parameters/console_suspend) to + turn on/off it dynamically. + + noaliencache [MM, NUMA, SLAB] Disables the allocation of alien + caches in the slab allocator. Saves per-node memory, + but will impact performance. + + noalign [KNL,ARM] + + noapic [SMP,APIC] Tells the kernel to not make use of any + IOAPICs that may be present in the system. + + noautogroup Disable scheduler automatic task group creation. + + nobats [PPC] Do not use BATs for mapping kernel lowmem + on "Classic" PPC cores. + + nocache [ARM] + + noclflush [BUGS=X86] Don't use the CLFLUSH instruction + + nodelayacct [KNL] Disable per-task delay accounting + + nodsp [SH] Disable hardware DSP at boot time. + + noefi Disable EFI runtime services support. + + noexec [IA-64] + + noexec [X86] + On X86-32 available only on PAE configured kernels. + noexec=on: enable non-executable mappings (default) + noexec=off: disable non-executable mappings + + nosmap [X86] + Disable SMAP (Supervisor Mode Access Prevention) + even if it is supported by processor. + + nosmep [X86] + Disable SMEP (Supervisor Mode Execution Prevention) + even if it is supported by processor. + + noexec32 [X86-64] + This affects only 32-bit executables. + noexec32=on: enable non-executable mappings (default) + read doesn't imply executable mappings + noexec32=off: disable non-executable mappings + read implies executable mappings + + nofpu [MIPS,SH] Disable hardware FPU at boot time. + + nofxsr [BUGS=X86-32] Disables x86 floating point extended + register save and restore. The kernel will only save + legacy floating-point registers on task switch. + + nohugeiomap [KNL,x86] Disable kernel huge I/O mappings. + + nosmt [KNL,S390] Disable symmetric multithreading (SMT). + Equivalent to smt=1. + + noxsave [BUGS=X86] Disables x86 extended register state save + and restore using xsave. The kernel will fallback to + enabling legacy floating-point and sse state. + + noxsaveopt [X86] Disables xsaveopt used in saving x86 extended + register states. The kernel will fall back to use + xsave to save the states. By using this parameter, + performance of saving the states is degraded because + xsave doesn't support modified optimization while + xsaveopt supports it on xsaveopt enabled systems. + + noxsaves [X86] Disables xsaves and xrstors used in saving and + restoring x86 extended register state in compacted + form of xsave area. The kernel will fall back to use + xsaveopt and xrstor to save and restore the states + in standard form of xsave area. By using this + parameter, xsave area per process might occupy more + memory on xsaves enabled systems. + + nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or + wfi(ARM) instruction doesn't work correctly and not to + use it. This is also useful when using JTAG debugger. + + no_file_caps Tells the kernel not to honor file capabilities. The + only way then for a file to be executed with privilege + is to be setuid root or executed by root. + + nohalt [IA-64] Tells the kernel not to use the power saving + function PAL_HALT_LIGHT when idle. This increases + power-consumption. On the positive side, it reduces + interrupt wake-up latency, which may improve performance + in certain environments such as networked servers or + real-time systems. + + nohibernate [HIBERNATION] Disable hibernation and resume. + + nohz= [KNL] Boottime enable/disable dynamic ticks + Valid arguments: on, off + Default: on + + nohz_full= [KNL,BOOT] + The argument is a cpu list, as described above. + In kernels built with CONFIG_NO_HZ_FULL=y, set + the specified list of CPUs whose tick will be stopped + whenever possible. The boot CPU will be forced outside + the range to maintain the timekeeping. + The CPUs in this range must also be included in the + rcu_nocbs= set. + + noiotrap [SH] Disables trapped I/O port accesses. + + noirqdebug [X86-32] Disables the code which attempts to detect and + disable unhandled interrupt sources. + + no_timer_check [X86,APIC] Disables the code which tests for + broken timer IRQ sources. + + noisapnp [ISAPNP] Disables ISA PnP code. + + noinitrd [RAM] Tells the kernel not to load any configured + initial RAM disk. + + nointremap [X86-64, Intel-IOMMU] Do not enable interrupt + remapping. + [Deprecated - use intremap=off] + + nointroute [IA-64] + + noinvpcid [X86] Disable the INVPCID cpu feature. + + nojitter [IA-64] Disables jitter checking for ITC timers. + + no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver + + no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page + fault handling. + + no-vmw-sched-clock + [X86,PV_OPS] Disable paravirtualized VMware scheduler + clock and use the default one. + + no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting. + steal time is computed, but won't influence scheduler + behaviour + + nolapic [X86-32,APIC] Do not enable or use the local APIC. + + nolapic_timer [X86-32,APIC] Do not use the local APIC timer. + + noltlbs [PPC] Do not use large page/tlb entries for kernel + lowmem mapping on PPC40x and PPC8xx + + nomca [IA-64] Disable machine check abort handling + + nomce [X86-32] Disable Machine Check Exception + + nomfgpt [X86-32] Disable Multi-Function General Purpose + Timer usage (for AMD Geode machines). + + nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to + shutdown the other cpus. Instead use the REBOOT_VECTOR + irq. + + nomodule Disable module load + + nopat [X86] Disable PAT (page attribute table extension of + pagetables) support. + + norandmaps Don't use address space randomization. Equivalent to + echo 0 > /proc/sys/kernel/randomize_va_space + + noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops + + noreplace-smp [X86-32,SMP] Don't replace SMP instructions + with UP alternatives + + nordrand [X86] Disable kernel use of the RDRAND and + RDSEED instructions even if they are supported + by the processor. RDRAND and RDSEED are still + available to user space applications. + + noresume [SWSUSP] Disables resume and restores original swap + space. + + no-scroll [VGA] Disables scrollback. + This is required for the Braillex ib80-piezo Braille + reader made by F.H. Papenmeier (Germany). + + nosbagart [IA-64] + + nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. + + nosmp [SMP] Tells an SMP kernel to act as a UP kernel, + and disable the IO APIC. legacy for "maxcpus=0". + + nosoftlockup [KNL] Disable the soft-lockup detector. + + nosync [HW,M68K] Disables sync negotiation for all devices. + + notsc [BUGS=X86-32] Disable Time Stamp Counter + + nowatchdog [KNL] Disable both lockup detectors, i.e. + soft-lockup and NMI watchdog (hard-lockup). + + nowb [ARM] + + nox2apic [X86-64,APIC] Do not enable x2APIC mode. + + cpu0_hotplug [X86] Turn on CPU0 hotplug feature when + CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. + Some features depend on CPU0. Known dependencies are: + 1. Resume from suspend/hibernate depends on CPU0. + Suspend/hibernate will fail if CPU0 is offline and you + need to online CPU0 before suspend/hibernate. + 2. PIC interrupts also depend on CPU0. CPU0 can't be + removed if a PIC interrupt is detected. + It's said poweroff/reboot may depend on CPU0 on some + machines although I haven't seen such issues so far + after CPU0 is offline on a few tested machines. + If the dependencies are under your control, you can + turn on cpu0_hotplug. + + nptcg= [IA-64] Override max number of concurrent global TLB + purges which is reported from either PAL_VM_SUMMARY or + SAL PALO. + + nr_cpus= [SMP] Maximum number of processors that an SMP kernel + could support. nr_cpus=n : n >= 1 limits the kernel to + support 'n' processors. It could be larger than the + number of already plugged CPU during bootup, later in + runtime you can physically add extra cpu until it reaches + n. So during boot up some boot time memory for per-cpu + variables need be pre-allocated for later physical cpu + hot plugging. + + nr_uarts= [SERIAL] maximum number of UARTs to be registered. + + numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing. + Allowed values are enable and disable + + numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. + one of ['zone', 'node', 'default'] can be specified + This can be set from sysctl after boot. + See Documentation/sysctl/vm.txt for details. + + ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. + See Documentation/debugging-via-ohci1394.txt for more + info. + + olpc_ec_timeout= [OLPC] ms delay when issuing EC commands + Rather than timing out after 20 ms if an EC + command is not properly ACKed, override the length + of the timeout. We have interrupts disabled while + waiting for the ACK, so if this is set too high + interrupts *may* be lost! + + omap_mux= [OMAP] Override bootloader pin multiplexing. + Format: <mux_mode0.mode_name=value>... + For example, to override I2C bus2: + omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 + + oprofile.timer= [HW] + Use timer interrupt instead of performance counters + + oprofile.cpu_type= Force an oprofile cpu type + This might be useful if you have an older oprofile + userland or if you want common events. + Format: { arch_perfmon } + arch_perfmon: [X86] Force use of architectural + perfmon on Intel CPUs instead of the + CPU specific event set. + timer: [X86] Force use of architectural NMI + timer mode (see also oprofile.timer + for generic hr timer mode) + + oops=panic Always panic on oopses. Default is to just kill the + process, but there is a small probability of + deadlocking the machine. + This will also cause panics on machine check exceptions. + Useful together with panic=30 to trigger a reboot. + + OSS [HW,OSS] + See Documentation/sound/oss/oss-parameters.txt + + page_owner= [KNL] Boot-time page_owner enabling option. + Storage of the information about who allocated + each page is disabled in default. With this switch, + we can turn it on. + on: enable the feature + + page_poison= [KNL] Boot-time parameter changing the state of + poisoning on the buddy allocator. + off: turn off poisoning + on: turn on poisoning + + panic= [KNL] Kernel behaviour on panic: delay <timeout> + timeout > 0: seconds before rebooting + timeout = 0: wait forever + timeout < 0: reboot immediately + Format: <timeout> + + panic_on_warn panic() instead of WARN(). Useful to cause kdump + on a WARN(). + + crash_kexec_post_notifiers + Run kdump after running panic-notifiers and dumping + kmsg. This only for the users who doubt kdump always + succeeds in any situation. + Note that this also increases risks of kdump failure, + because some panic notifiers can make the crashed + kernel more unstable. + + parkbd.port= [HW] Parallel port number the keyboard adapter is + connected to, default is 0. + Format: <parport#> + parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, + 0 for XT, 1 for AT (default is AT). + Format: <mode> + + parport= [HW,PPT] Specify parallel ports. 0 disables. + Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } + Use 'auto' to force the driver to use any + IRQ/DMA settings detected (the default is to + ignore detected IRQ/DMA settings because of + possible conflicts). You can specify the base + address, IRQ, and DMA settings; IRQ and DMA + should be numbers, or 'auto' (for using detected + settings on that particular port), or 'nofifo' + (to avoid using a FIFO even if it is detected). + Parallel ports are assigned in the order they + are specified on the command line, starting + with parport0. + + parport_init_mode= [HW,PPT] + Configure VIA parallel port to operate in + a specific mode. This is necessary on Pegasos + computer where firmware has no options for setting + up parallel port mode and sets it to spp. + Currently this function knows 686a and 8231 chips. + Format: [spp|ps2|epp|ecp|ecpepp] + + pause_on_oops= + Halt all CPUs after the first oops has been printed for + the specified number of seconds. This is to be used if + your oopses keep scrolling off the screen. + + pcbit= [HW,ISDN] + + pcd. [PARIDE] + See header of drivers/block/paride/pcd.c. + See also Documentation/blockdev/paride.txt. + + pci=option[,option...] [PCI] various PCI subsystem options: + earlydump [X86] dump PCI config space before the kernel + changes anything + off [X86] don't probe for the PCI bus + bios [X86-32] force use of PCI BIOS, don't access + the hardware directly. Use this if your machine + has a non-standard PCI host bridge. + nobios [X86-32] disallow use of PCI BIOS, only direct + hardware access methods are allowed. Use this + if you experience crashes upon bootup and you + suspect they are caused by the BIOS. + conf1 [X86] Force use of PCI Configuration Access + Mechanism 1 (config address in IO port 0xCF8, + data in IO port 0xCFC, both 32-bit). + conf2 [X86] Force use of PCI Configuration Access + Mechanism 2 (IO port 0xCF8 is an 8-bit port for + the function, IO port 0xCFA, also 8-bit, sets + bus number. The config space is then accessed + through ports 0xC000-0xCFFF). + See http://wiki.osdev.org/PCI for more info + on the configuration access mechanisms. + noaer [PCIE] If the PCIEAER kernel config parameter is + enabled, this kernel boot option can be used to + disable the use of PCIE advanced error reporting. + nodomains [PCI] Disable support for multiple PCI + root domains (aka PCI segments, in ACPI-speak). + nommconf [X86] Disable use of MMCONFIG for PCI + Configuration + check_enable_amd_mmconf [X86] check for and enable + properly configured MMIO access to PCI + config space on AMD family 10h CPU + nomsi [MSI] If the PCI_MSI kernel config parameter is + enabled, this kernel boot option can be used to + disable the use of MSI interrupts system-wide. + noioapicquirk [APIC] Disable all boot interrupt quirks. + Safety option to keep boot IRQs enabled. This + should never be necessary. + ioapicreroute [APIC] Enable rerouting of boot IRQs to the + primary IO-APIC for bridges that cannot disable + boot IRQs. This fixes a source of spurious IRQs + when the system masks IRQs. + noioapicreroute [APIC] Disable workaround that uses the + boot IRQ equivalent of an IRQ that connects to + a chipset where boot IRQs cannot be disabled. + The opposite of ioapicreroute. + biosirq [X86-32] Use PCI BIOS calls to get the interrupt + routing table. These calls are known to be buggy + on several machines and they hang the machine + when used, but on other computers it's the only + way to get the interrupt routing table. Try + this option if the kernel is unable to allocate + IRQs or discover secondary PCI buses on your + motherboard. + rom [X86] Assign address space to expansion ROMs. + Use with caution as certain devices share + address decoders between ROMs and other + resources. + norom [X86] Do not assign address space to + expansion ROMs that do not already have + BIOS assigned address ranges. + nobar [X86] Do not assign address space to the + BARs that weren't assigned by the BIOS. + irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be + assigned automatically to PCI devices. You can + make the kernel exclude IRQs of your ISA cards + this way. + pirqaddr=0xAAAAA [X86] Specify the physical address + of the PIRQ table (normally generated + by the BIOS) if it is outside the + F0000h-100000h range. + lastbus=N [X86] Scan all buses thru bus #N. Can be + useful if the kernel is unable to find your + secondary buses and you want to tell it + explicitly which ones they are. + assign-busses [X86] Always assign all PCI bus + numbers ourselves, overriding + whatever the firmware may have done. + usepirqmask [X86] Honor the possible IRQ mask stored + in the BIOS $PIR table. This is needed on + some systems with broken BIOSes, notably + some HP Pavilion N5400 and Omnibook XE3 + notebooks. This will have no effect if ACPI + IRQ routing is enabled. + noacpi [X86] Do not use ACPI for IRQ routing + or for PCI scanning. + use_crs [X86] Use PCI host bridge window information + from ACPI. On BIOSes from 2008 or later, this + is enabled by default. If you need to use this, + please report a bug. + nocrs [X86] Ignore PCI host bridge windows from ACPI. + If you need to use this, please report a bug. + routeirq Do IRQ routing for all PCI devices. + This is normally done in pci_enable_device(), + so this option is a temporary workaround + for broken drivers that don't call it. + skip_isa_align [X86] do not align io start addr, so can + handle more pci cards + noearly [X86] Don't do any early type 1 scanning. + This might help on some broken boards which + machine check when some devices' config space + is read. But various workarounds are disabled + and some IOMMU drivers will not work. + bfsort Sort PCI devices into breadth-first order. + This sorting is done to get a device + order compatible with older (<= 2.4) kernels. + nobfsort Don't sort PCI devices into breadth-first order. + pcie_bus_tune_off Disable PCIe MPS (Max Payload Size) + tuning and use the BIOS-configured MPS defaults. + pcie_bus_safe Set every device's MPS to the largest value + supported by all devices below the root complex. + pcie_bus_perf Set device MPS to the largest allowable MPS + based on its parent bus. Also set MRRS (Max + Read Request Size) to the largest supported + value (no larger than the MPS that the device + or bus can support) for best performance. + pcie_bus_peer2peer Set every device's MPS to 128B, which + every device is guaranteed to support. This + configuration allows peer-to-peer DMA between + any pair of devices, possibly at the cost of + reduced performance. This also guarantees + that hot-added devices will work. + cbiosize=nn[KMG] The fixed amount of bus space which is + reserved for the CardBus bridge's IO window. + The default value is 256 bytes. + cbmemsize=nn[KMG] The fixed amount of bus space which is + reserved for the CardBus bridge's memory + window. The default value is 64 megabytes. + resource_alignment= + Format: + [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] + [<order of align>@]pci:<vendor>:<device>\ + [:<subvendor>:<subdevice>][; ...] + Specifies alignment and device to reassign + aligned memory resources. + If <order of align> is not specified, + PAGE_SIZE is used as alignment. + PCI-PCI bridge can be specified, if resource + windows need to be expanded. + To specify the alignment for several + instances of a device, the PCI vendor, + device, subvendor, and subdevice may be + specified, e.g., 4096@pci:8086:9c22:103c:198f + ecrc= Enable/disable PCIe ECRC (transaction layer + end-to-end CRC checking). + bios: Use BIOS/firmware settings. This is the + the default. + off: Turn ECRC off + on: Turn ECRC on. + hpiosize=nn[KMG] The fixed amount of bus space which is + reserved for hotplug bridge's IO window. + Default size is 256 bytes. + hpmemsize=nn[KMG] The fixed amount of bus space which is + reserved for hotplug bridge's memory window. + Default size is 2 megabytes. + hpbussize=nn The minimum amount of additional bus numbers + reserved for buses below a hotplug bridge. + Default is 1. + realloc= Enable/disable reallocating PCI bridge resources + if allocations done by BIOS are too small to + accommodate resources required by all child + devices. + off: Turn realloc off + on: Turn realloc on + realloc same as realloc=on + noari do not use PCIe ARI. + pcie_scan_all Scan all possible PCIe devices. Otherwise we + only look for one device below a PCIe downstream + port. + + pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power + Management. + off Disable ASPM. + force Enable ASPM even on devices that claim not to support it. + WARNING: Forcing ASPM on may cause system lockups. + + pcie_hp= [PCIE] PCI Express Hotplug driver options: + nomsi Do not use MSI for PCI Express Native Hotplug (this + makes all PCIe ports use INTx for hotplug services). + + pcie_ports= [PCIE] PCIe ports handling: + auto Ask the BIOS whether or not to use native PCIe services + associated with PCIe ports (PME, hot-plug, AER). Use + them only if that is allowed by the BIOS. + native Use native PCIe services associated with PCIe ports + unconditionally. + compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe + ports driver. + + pcie_port_pm= [PCIE] PCIe port power management handling: + off Disable power management of all PCIe ports + force Forcibly enable power management of all PCIe ports + + pcie_pme= [PCIE,PM] Native PCIe PME signaling options: + nomsi Do not use MSI for native PCIe PME signaling (this makes + all PCIe root ports use INTx for all services). + + pcmv= [HW,PCMCIA] BadgePAD 4 + + pd_ignore_unused + [PM] + Keep all power-domains already enabled by bootloader on, + even if no driver has claimed them. This is useful + for debug and development, but should not be + needed on a platform with proper driver support. + + pd. [PARIDE] + See Documentation/blockdev/paride.txt. + + pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at + boot time. + Format: { 0 | 1 } + See arch/parisc/kernel/pdc_chassis.c + + percpu_alloc= Select which percpu first chunk allocator to use. + Currently supported values are "embed" and "page". + Archs may support subset or none of the selections. + See comments in mm/percpu.c for details on each + allocator. This parameter is primarily for debugging + and performance comparison. + + pf. [PARIDE] + See Documentation/blockdev/paride.txt. + + pg. [PARIDE] + See Documentation/blockdev/paride.txt. + + pirq= [SMP,APIC] Manual mp-table setup + See Documentation/x86/i386/IO-APIC.txt. + + plip= [PPT,NET] Parallel port network link + Format: { parport<nr> | timid | 0 } + See also Documentation/parport.txt. + + pmtmr= [X86] Manual setup of pmtmr I/O Port. + Override pmtimer IOPort with a hex value. + e.g. pmtmr=0x508 + + pnp.debug=1 [PNP] + Enable PNP debug messages (depends on the + CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time + via /sys/module/pnp/parameters/debug. We always show + current resource usage; turning this on also shows + possible settings and some assignment information. + + pnpacpi= [ACPI] + { off } + + pnpbios= [ISAPNP] + { on | off | curr | res | no-curr | no-res } + + pnp_reserve_irq= + [ISAPNP] Exclude IRQs for the autoconfiguration + + pnp_reserve_dma= + [ISAPNP] Exclude DMAs for the autoconfiguration + + pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration + Ranges are in pairs (I/O port base and size). + + pnp_reserve_mem= + [ISAPNP] Exclude memory regions for the + autoconfiguration. + Ranges are in pairs (memory base and size). + + ports= [IP_VS_FTP] IPVS ftp helper module + Default is 21. + Up to 8 (IP_VS_APP_MAX_PORTS) ports + may be specified. + Format: <port>,<port>.... + + powersave=off [PPC] This option disables power saving features. + It specifically disables cpuidle and sets the + platform machine description specific power_save + function to NULL. On Idle the CPU just reduces + execution priority. + + ppc_strict_facility_enable + [PPC] This option catches any kernel floating point, + Altivec, VSX and SPE outside of regions specifically + allowed (eg kernel_enable_fpu()/kernel_disable_fpu()). + There is some performance impact when enabling this. + + print-fatal-signals= + [KNL] debug: print fatal signals + + If enabled, warn about various signal handling + related application anomalies: too many signals, + too many POSIX.1 timers, fatal signals causing a + coredump - etc. + + If you hit the warning due to signal overflow, + you might want to try "ulimit -i unlimited". + + default: off. + + printk.always_kmsg_dump= + Trigger kmsg_dump for cases other than kernel oops or + panics + Format: <bool> (1/Y/y=enable, 0/N/n=disable) + default: disabled + + printk.devkmsg={on,off,ratelimit} + Control writing to /dev/kmsg. + on - unlimited logging to /dev/kmsg from userspace + off - logging to /dev/kmsg disabled + ratelimit - ratelimit the logging + Default: ratelimit + + printk.time= Show timing data prefixed to each printk message line + Format: <bool> (1/Y/y=enable, 0/N/n=disable) + + processor.max_cstate= [HW,ACPI] + Limit processor to maximum C-state + max_cstate=9 overrides any DMI blacklist limit. + + processor.nocst [HW,ACPI] + Ignore the _CST method to determine C-states, + instead using the legacy FADT method + + profile= [KNL] Enable kernel profiling via /proc/profile + Format: [schedule,]<number> + Param: "schedule" - profile schedule points. + Param: <number> - step/bucket size as a power of 2 for + statistical time based profiling. + Param: "sleep" - profile D-state sleeping (millisecs). + Requires CONFIG_SCHEDSTATS + Param: "kvm" - profile VM exits. + + prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk + before loading. + See Documentation/blockdev/ramdisk.txt. + + psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to + probe for; one of (bare|imps|exps|lifebook|any). + psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports + per second. + psmouse.resetafter= [HW,MOUSE] + Try to reset the device after so many bad packets + (0 = never). + psmouse.resolution= + [HW,MOUSE] Set desired mouse resolution, in dpi. + psmouse.smartscroll= + [HW,MOUSE] Controls Logitech smartscroll autorepeat. + 0 = disabled, 1 = enabled (default). + + pstore.backend= Specify the name of the pstore backend to use + + pt. [PARIDE] + See Documentation/blockdev/paride.txt. + + pty.legacy_count= + [KNL] Number of legacy pty's. Overwrites compiled-in + default number. + + quiet [KNL] Disable most log messages + + r128= [HW,DRM] + + raid= [HW,RAID] + See Documentation/admin-guide/md.rst. + + ramdisk_size= [RAM] Sizes of RAM disks in kilobytes + See Documentation/blockdev/ramdisk.txt. + + rcu_nocbs= [KNL] + The argument is a cpu list, as described above. + + In kernels built with CONFIG_RCU_NOCB_CPU=y, set + the specified list of CPUs to be no-callback CPUs. + Invocation of these CPUs' RCU callbacks will + be offloaded to "rcuox/N" kthreads created for + that purpose, where "x" is "b" for RCU-bh, "p" + for RCU-preempt, and "s" for RCU-sched, and "N" + is the CPU number. This reduces OS jitter on the + offloaded CPUs, which can be useful for HPC and + real-time workloads. It can also improve energy + efficiency for asymmetric multiprocessors. + + rcu_nocb_poll [KNL] + Rather than requiring that offloaded CPUs + (specified by rcu_nocbs= above) explicitly + awaken the corresponding "rcuoN" kthreads, + make these kthreads poll for callbacks. + This improves the real-time response for the + offloaded CPUs by relieving them of the need to + wake up the corresponding kthread, but degrades + energy efficiency by requiring that the kthreads + periodically wake up to do the polling. + + rcutree.blimit= [KNL] + Set maximum number of finished RCU callbacks to + process in one batch. + + rcutree.dump_tree= [KNL] + Dump the structure of the rcu_node combining tree + out at early boot. This is used for diagnostic + purposes, to verify correct tree setup. + + rcutree.gp_cleanup_delay= [KNL] + Set the number of jiffies to delay each step of + RCU grace-period cleanup. This only has effect + when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set. + + rcutree.gp_init_delay= [KNL] + Set the number of jiffies to delay each step of + RCU grace-period initialization. This only has + effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT + is set. + + rcutree.gp_preinit_delay= [KNL] + Set the number of jiffies to delay each step of + RCU grace-period pre-initialization, that is, + the propagation of recent CPU-hotplug changes up + the rcu_node combining tree. This only has effect + when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set. + + rcutree.rcu_fanout_exact= [KNL] + Disable autobalancing of the rcu_node combining + tree. This is used by rcutorture, and might + possibly be useful for architectures having high + cache-to-cache transfer latencies. + + rcutree.rcu_fanout_leaf= [KNL] + Change the number of CPUs assigned to each + leaf rcu_node structure. Useful for very + large systems, which will choose the value 64, + and for NUMA systems with large remote-access + latencies, which will choose a value aligned + with the appropriate hardware boundaries. + + rcutree.jiffies_till_sched_qs= [KNL] + Set required age in jiffies for a + given grace period before RCU starts + soliciting quiescent-state help from + rcu_note_context_switch(). + + rcutree.jiffies_till_first_fqs= [KNL] + Set delay from grace-period initialization to + first attempt to force quiescent states. + Units are jiffies, minimum value is zero, + and maximum value is HZ. + + rcutree.jiffies_till_next_fqs= [KNL] + Set delay between subsequent attempts to force + quiescent states. Units are jiffies, minimum + value is one, and maximum value is HZ. + + rcutree.kthread_prio= [KNL,BOOT] + Set the SCHED_FIFO priority of the RCU per-CPU + kthreads (rcuc/N). This value is also used for + the priority of the RCU boost threads (rcub/N) + and for the RCU grace-period kthreads (rcu_bh, + rcu_preempt, and rcu_sched). If RCU_BOOST is + set, valid values are 1-99 and the default is 1 + (the least-favored priority). Otherwise, when + RCU_BOOST is not set, valid values are 0-99 and + the default is zero (non-realtime operation). + + rcutree.rcu_nocb_leader_stride= [KNL] + Set the number of NOCB kthread groups, which + defaults to the square root of the number of + CPUs. Larger numbers reduces the wakeup overhead + on the per-CPU grace-period kthreads, but increases + that same overhead on each group's leader. + + rcutree.qhimark= [KNL] + Set threshold of queued RCU callbacks beyond which + batch limiting is disabled. + + rcutree.qlowmark= [KNL] + Set threshold of queued RCU callbacks below which + batch limiting is re-enabled. + + rcutree.rcu_idle_gp_delay= [KNL] + Set wakeup interval for idle CPUs that have + RCU callbacks (RCU_FAST_NO_HZ=y). + + rcutree.rcu_idle_lazy_gp_delay= [KNL] + Set wakeup interval for idle CPUs that have + only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y). + Lazy RCU callbacks are those which RCU can + prove do nothing more than free memory. + + rcuperf.gp_exp= [KNL] + Measure performance of expedited synchronous + grace-period primitives. + + rcuperf.holdoff= [KNL] + Set test-start holdoff period. The purpose of + this parameter is to delay the start of the + test until boot completes in order to avoid + interference. + + rcuperf.nreaders= [KNL] + Set number of RCU readers. The value -1 selects + N, where N is the number of CPUs. A value + "n" less than -1 selects N-n+1, where N is again + the number of CPUs. For example, -2 selects N + (the number of CPUs), -3 selects N+1, and so on. + A value of "n" less than or equal to -N selects + a single reader. + + rcuperf.nwriters= [KNL] + Set number of RCU writers. The values operate + the same as for rcuperf.nreaders. + N, where N is the number of CPUs + + rcuperf.perf_runnable= [BOOT] + Start rcuperf running at boot time. + + rcuperf.shutdown= [KNL] + Shut the system down after performance tests + complete. This is useful for hands-off automated + testing. + + rcuperf.perf_type= [KNL] + Specify the RCU implementation to test. + + rcuperf.verbose= [KNL] + Enable additional printk() statements. + + rcutorture.cbflood_inter_holdoff= [KNL] + Set holdoff time (jiffies) between successive + callback-flood tests. + + rcutorture.cbflood_intra_holdoff= [KNL] + Set holdoff time (jiffies) between successive + bursts of callbacks within a given callback-flood + test. + + rcutorture.cbflood_n_burst= [KNL] + Set the number of bursts making up a given + callback-flood test. Set this to zero to + disable callback-flood testing. + + rcutorture.cbflood_n_per_burst= [KNL] + Set the number of callbacks to be registered + in a given burst of a callback-flood test. + + rcutorture.fqs_duration= [KNL] + Set duration of force_quiescent_state bursts + in microseconds. + + rcutorture.fqs_holdoff= [KNL] + Set holdoff time within force_quiescent_state bursts + in microseconds. + + rcutorture.fqs_stutter= [KNL] + Set wait time between force_quiescent_state bursts + in seconds. + + rcutorture.gp_cond= [KNL] + Use conditional/asynchronous update-side + primitives, if available. + + rcutorture.gp_exp= [KNL] + Use expedited update-side primitives, if available. + + rcutorture.gp_normal= [KNL] + Use normal (non-expedited) asynchronous + update-side primitives, if available. + + rcutorture.gp_sync= [KNL] + Use normal (non-expedited) synchronous + update-side primitives, if available. If all + of rcutorture.gp_cond=, rcutorture.gp_exp=, + rcutorture.gp_normal=, and rcutorture.gp_sync= + are zero, rcutorture acts as if is interpreted + they are all non-zero. + + rcutorture.n_barrier_cbs= [KNL] + Set callbacks/threads for rcu_barrier() testing. + + rcutorture.nfakewriters= [KNL] + Set number of concurrent RCU writers. These just + stress RCU, they don't participate in the actual + test, hence the "fake". + + rcutorture.nreaders= [KNL] + Set number of RCU readers. The value -1 selects + N-1, where N is the number of CPUs. A value + "n" less than -1 selects N-n-2, where N is again + the number of CPUs. For example, -2 selects N + (the number of CPUs), -3 selects N+1, and so on. + + rcutorture.object_debug= [KNL] + Enable debug-object double-call_rcu() testing. + + rcutorture.onoff_holdoff= [KNL] + Set time (s) after boot for CPU-hotplug testing. + + rcutorture.onoff_interval= [KNL] + Set time (s) between CPU-hotplug operations, or + zero to disable CPU-hotplug testing. + + rcutorture.shuffle_interval= [KNL] + Set task-shuffle interval (s). Shuffling tasks + allows some CPUs to go into dyntick-idle mode + during the rcutorture test. + + rcutorture.shutdown_secs= [KNL] + Set time (s) after boot system shutdown. This + is useful for hands-off automated testing. + + rcutorture.stall_cpu= [KNL] + Duration of CPU stall (s) to test RCU CPU stall + warnings, zero to disable. + + rcutorture.stall_cpu_holdoff= [KNL] + Time to wait (s) after boot before inducing stall. + + rcutorture.stat_interval= [KNL] + Time (s) between statistics printk()s. + + rcutorture.stutter= [KNL] + Time (s) to stutter testing, for example, specifying + five seconds causes the test to run for five seconds, + wait for five seconds, and so on. This tests RCU's + ability to transition abruptly to and from idle. + + rcutorture.test_boost= [KNL] + Test RCU priority boosting? 0=no, 1=maybe, 2=yes. + "Maybe" means test if the RCU implementation + under test support RCU priority boosting. + + rcutorture.test_boost_duration= [KNL] + Duration (s) of each individual boost test. + + rcutorture.test_boost_interval= [KNL] + Interval (s) between each boost test. + + rcutorture.test_no_idle_hz= [KNL] + Test RCU's dyntick-idle handling. See also the + rcutorture.shuffle_interval parameter. + + rcutorture.torture_runnable= [BOOT] + Start rcutorture running at boot time. + + rcutorture.torture_type= [KNL] + Specify the RCU implementation to test. + + rcutorture.verbose= [KNL] + Enable additional printk() statements. + + rcupdate.rcu_cpu_stall_suppress= [KNL] + Suppress RCU CPU stall warning messages. + + rcupdate.rcu_cpu_stall_timeout= [KNL] + Set timeout for RCU CPU stall warning messages. + + rcupdate.rcu_expedited= [KNL] + Use expedited grace-period primitives, for + example, synchronize_rcu_expedited() instead + of synchronize_rcu(). This reduces latency, + but can increase CPU utilization, degrade + real-time latency, and degrade energy efficiency. + No effect on CONFIG_TINY_RCU kernels. + + rcupdate.rcu_normal= [KNL] + Use only normal grace-period primitives, + for example, synchronize_rcu() instead of + synchronize_rcu_expedited(). This improves + real-time latency, CPU utilization, and + energy efficiency, but can expose users to + increased grace-period latency. This parameter + overrides rcupdate.rcu_expedited. No effect on + CONFIG_TINY_RCU kernels. + + rcupdate.rcu_normal_after_boot= [KNL] + Once boot has completed (that is, after + rcu_end_inkernel_boot() has been invoked), use + only normal grace-period primitives. No effect + on CONFIG_TINY_RCU kernels. + + rcupdate.rcu_task_stall_timeout= [KNL] + Set timeout in jiffies for RCU task stall warning + messages. Disable with a value less than or equal + to zero. + + rcupdate.rcu_self_test= [KNL] + Run the RCU early boot self tests + + rcupdate.rcu_self_test_bh= [KNL] + Run the RCU bh early boot self tests + + rcupdate.rcu_self_test_sched= [KNL] + Run the RCU sched early boot self tests + + rdinit= [KNL] + Format: <full_path> + Run specified binary instead of /init from the ramdisk, + used for early userspace startup. See initrd. + + reboot= [KNL] + Format (x86 or x86_64): + [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \ + [[,]s[mp]#### \ + [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \ + [[,]f[orce] + Where reboot_mode is one of warm (soft) or cold (hard) or gpio, + reboot_type is one of bios, acpi, kbd, triple, efi, or pci, + reboot_force is either force or not specified, + reboot_cpu is s[mp]#### with #### being the processor + to be used for rebooting. + + relax_domain_level= + [KNL, SMP] Set scheduler's default relax_domain_level. + See Documentation/cgroup-v1/cpusets.txt. + + reserve= [KNL,BUGS] Force the kernel to ignore some iomem area + + reservetop= [X86-32] + Format: nn[KMG] + Reserves a hole at the top of the kernel virtual + address space. + + reservelow= [X86] + Format: nn[K] + Set the amount of memory to reserve for BIOS at + the bottom of the address space. + + reset_devices [KNL] Force drivers to reset the underlying device + during initialization. + + resume= [SWSUSP] + Specify the partition device for software suspend + Format: + {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>} + + resume_offset= [SWSUSP] + Specify the offset from the beginning of the partition + given by "resume=" at which the swap header is located, + in <PAGE_SIZE> units (needed only for swap files). + See Documentation/power/swsusp-and-swap-files.txt + + resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to + read the resume files + + resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up. + Useful for devices that are detected asynchronously + (e.g. USB and MMC devices). + + hibernate= [HIBERNATION] + noresume Don't check if there's a hibernation image + present during boot. + nocompress Don't compress/decompress hibernation images. + no Disable hibernation and resume. + protect_image Turn on image protection during restoration + (that will set all pages holding image data + during restoration read-only). + + retain_initrd [RAM] Keep initrd memory after extraction + + rfkill.default_state= + 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm, + etc. communication is blocked by default. + 1 Unblocked. + + rfkill.master_switch_mode= + 0 The "airplane mode" button does nothing. + 1 The "airplane mode" button toggles between everything + blocked and the previous configuration. + 2 The "airplane mode" button toggles between everything + blocked and everything unblocked. + + rhash_entries= [KNL,NET] + Set number of hash buckets for route cache + + ro [KNL] Mount root device read-only on boot + + rodata= [KNL] + on Mark read-only kernel memory as read-only (default). + off Leave read-only kernel memory writable for debugging. + + rockchip.usb_uart + Enable the uart passthrough on the designated usb port + on Rockchip SoCs. When active, the signals of the + debug-uart get routed to the D+ and D- pins of the usb + port and the regular usb controller gets disabled. + + root= [KNL] Root filesystem + See name_to_dev_t comment in init/do_mounts.c. + + rootdelay= [KNL] Delay (in seconds) to pause before attempting to + mount the root filesystem + + rootflags= [KNL] Set root filesystem mount option string + + rootfstype= [KNL] Set root filesystem type + + rootwait [KNL] Wait (indefinitely) for root device to show up. + Useful for devices that are detected asynchronously + (e.g. USB and MMC devices). + + rproc_mem=nn[KMG][@address] + [KNL,ARM,CMA] Remoteproc physical memory block. + Memory area to be used by remote processor image, + managed by CMA. + + rw [KNL] Mount root device read-write on boot + + S [KNL] Run init in single mode + + s390_iommu= [HW,S390] + Set s390 IOTLB flushing mode + strict + With strict flushing every unmap operation will result in + an IOTLB flush. Default is lazy flushing before reuse, + which is faster. + + sa1100ir [NET] + See drivers/net/irda/sa1100_ir.c. + + sbni= [NET] Granch SBNI12 leased line adapter + + sched_debug [KNL] Enables verbose scheduler debug messages. + + schedstats= [KNL,X86] Enable or disable scheduled statistics. + Allowed values are enable and disable. This feature + incurs a small amount of overhead in the scheduler + but is useful for debugging and performance tuning. + + skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate + xtime_lock contention on larger systems, and/or RCU lock + contention on all systems with CONFIG_MAXSMP set. + Format: { "0" | "1" } + 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1" + 1 -- enable. + Note: increases power consumption, thus should only be + enabled if running jitter sensitive (HPC/RT) workloads. + + security= [SECURITY] Choose a security module to enable at boot. + If this boot parameter is not specified, only the first + security module asking for security registration will be + loaded. An invalid security module name will be treated + as if no module has been chosen. + + selinux= [SELINUX] Disable or enable SELinux at boot time. + Format: { "0" | "1" } + See security/selinux/Kconfig help text. + 0 -- disable. + 1 -- enable. + Default value is set via kernel config option. + If enabled at boot time, /selinux/disable can be used + later to disable prior to initial policy load. + + apparmor= [APPARMOR] Disable or enable AppArmor at boot time + Format: { "0" | "1" } + See security/apparmor/Kconfig help text + 0 -- disable. + 1 -- enable. + Default value is set via kernel config option. + + serialnumber [BUGS=X86-32] + + shapers= [NET] + Maximal number of shapers. + + simeth= [IA-64] + simscsi= + + slram= [HW,MTD] + + slab_nomerge [MM] + Disable merging of slabs with similar size. May be + necessary if there is some reason to distinguish + allocs to different slabs. Debug options disable + merging on their own. + For more information see Documentation/vm/slub.txt. + + slab_max_order= [MM, SLAB] + Determines the maximum allowed order for slabs. + A high setting may cause OOMs due to memory + fragmentation. Defaults to 1 for systems with + more than 32MB of RAM, 0 otherwise. + + slub_debug[=options[,slabs]] [MM, SLUB] + Enabling slub_debug allows one to determine the + culprit if slab objects become corrupted. Enabling + slub_debug can create guard zones around objects and + may poison objects when not in use. Also tracks the + last alloc / free. For more information see + Documentation/vm/slub.txt. + + slub_max_order= [MM, SLUB] + Determines the maximum allowed order for slabs. + A high setting may cause OOMs due to memory + fragmentation. For more information see + Documentation/vm/slub.txt. + + slub_min_objects= [MM, SLUB] + The minimum number of objects per slab. SLUB will + increase the slab order up to slub_max_order to + generate a sufficiently large slab able to contain + the number of objects indicated. The higher the number + of objects the smaller the overhead of tracking slabs + and the less frequently locks need to be acquired. + For more information see Documentation/vm/slub.txt. + + slub_min_order= [MM, SLUB] + Determines the minimum page order for slabs. Must be + lower than slub_max_order. + For more information see Documentation/vm/slub.txt. + + slub_nomerge [MM, SLUB] + Same with slab_nomerge. This is supported for legacy. + See slab_nomerge for more information. + + smart2= [HW] + Format: <io1>[,<io2>[,...,<io8>]] + + smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices + smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port + smsc-ircc2.ircc_sir= [HW] SIR base I/O port + smsc-ircc2.ircc_fir= [HW] FIR base I/O port + smsc-ircc2.ircc_irq= [HW] IRQ line + smsc-ircc2.ircc_dma= [HW] DMA channel + smsc-ircc2.ircc_transceiver= [HW] Transceiver type: + 0: Toshiba Satellite 1800 (GP data pin select) + 1: Fast pin select (default) + 2: ATC IRMode + + smt [KNL,S390] Set the maximum number of threads (logical + CPUs) to use per physical CPU on systems capable of + symmetric multithreading (SMT). Will be capped to the + actual hardware limit. + Format: <integer> + Default: -1 (no limit) + + softlockup_panic= + [KNL] Should the soft-lockup detector generate panics. + Format: <integer> + + softlockup_all_cpu_backtrace= + [KNL] Should the soft-lockup detector generate + backtraces on all cpus. + Format: <integer> + + sonypi.*= [HW] Sony Programmable I/O Control Device driver + See Documentation/laptops/sonypi.txt + + spia_io_base= [HW,MTD] + spia_fio_base= + spia_pedr= + spia_peddr= + + stacktrace [FTRACE] + Enabled the stack tracer on boot up. + + stacktrace_filter=[function-list] + [FTRACE] Limit the functions that the stack tracer + will trace at boot up. function-list is a comma separated + list of functions. This list can be changed at run + time by the stack_trace_filter file in the debugfs + tracing directory. Note, this enables stack tracing + and the stacktrace above is not needed. + + sti= [PARISC,HW] + Format: <num> + Set the STI (builtin display/keyboard on the HP-PARISC + machines) console (graphic card) which should be used + as the initial boot-console. + See also comment in drivers/video/console/sticore.c. + + sti_font= [HW] + See comment in drivers/video/console/sticore.c. + + stifb= [HW] + Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] + + sunrpc.min_resvport= + sunrpc.max_resvport= + [NFS,SUNRPC] + SunRPC servers often require that client requests + originate from a privileged port (i.e. a port in the + range 0 < portnr < 1024). + An administrator who wishes to reserve some of these + ports for other uses may adjust the range that the + kernel's sunrpc client considers to be privileged + using these two parameters to set the minimum and + maximum port values. + + sunrpc.svc_rpc_per_connection_limit= + [NFS,SUNRPC] + Limit the number of requests that the server will + process in parallel from a single connection. + The default value is 0 (no limit). + + sunrpc.pool_mode= + [NFS] + Control how the NFS server code allocates CPUs to + service thread pools. Depending on how many NICs + you have and where their interrupts are bound, this + option will affect which CPUs will do NFS serving. + Note: this parameter cannot be changed while the + NFS server is running. + + auto the server chooses an appropriate mode + automatically using heuristics + global a single global pool contains all CPUs + percpu one pool for each CPU + pernode one pool for each NUMA node (equivalent + to global on non-NUMA machines) + + sunrpc.tcp_slot_table_entries= + sunrpc.udp_slot_table_entries= + [NFS,SUNRPC] + Sets the upper limit on the number of simultaneous + RPC calls that can be sent from the client to a + server. Increasing these values may allow you to + improve throughput, but will also increase the + amount of memory reserved for use by the client. + + suspend.pm_test_delay= + [SUSPEND] + Sets the number of seconds to remain in a suspend test + mode before resuming the system (see + /sys/power/pm_test). Only available when CONFIG_PM_DEBUG + is set. Default value is 5. + + swapaccount=[0|1] + [KNL] Enable accounting of swap in memory resource + controller if no parameter or 1 is given or disable + it if 0 is given (See Documentation/cgroup-v1/memory.txt) + + swiotlb= [ARM,IA-64,PPC,MIPS,X86] + Format: { <int> | force } + <int> -- Number of I/O TLB slabs + force -- force using of bounce buffers even if they + wouldn't be automatically used by the kernel + + switches= [HW,M68k] + + sysfs.deprecated=0|1 [KNL] + Enable/disable old style sysfs layout for old udev + on older distributions. When this option is enabled + very new udev will not work anymore. When this option + is disabled (or CONFIG_SYSFS_DEPRECATED not compiled) + in older udev will not work anymore. + Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in + the kernel configuration. + + sysrq_always_enabled + [KNL] + Ignore sysrq setting - this boot parameter will + neutralize any effect of /proc/sys/kernel/sysrq. + Useful for debugging. + + tcpmhash_entries= [KNL,NET] + Set the number of tcp_metrics_hash slots. + Default value is 8192 or 16384 depending on total + ram pages. This is used to specify the TCP metrics + cache size. See Documentation/networking/ip-sysctl.txt + "tcp_no_metrics_save" section for more details. + + tdfx= [HW,DRM] + + test_suspend= [SUSPEND][,N] + Specify "mem" (for Suspend-to-RAM) or "standby" (for + standby suspend) or "freeze" (for suspend type freeze) + as the system sleep state during system startup with + the optional capability to repeat N number of times. + The system is woken from this state using a + wakeup-capable RTC alarm. + + thash_entries= [KNL,NET] + Set number of hash buckets for TCP connection + + thermal.act= [HW,ACPI] + -1: disable all active trip points in all thermal zones + <degrees C>: override all lowest active trip points + + thermal.crt= [HW,ACPI] + -1: disable all critical trip points in all thermal zones + <degrees C>: override all critical trip points + + thermal.nocrt= [HW,ACPI] + Set to disable actions on ACPI thermal zone + critical and hot trip points. + + thermal.off= [HW,ACPI] + 1: disable ACPI thermal control + + thermal.psv= [HW,ACPI] + -1: disable all passive trip points + <degrees C>: override all passive trip points to this + value + + thermal.tzp= [HW,ACPI] + Specify global default ACPI thermal zone polling rate + <deci-seconds>: poll all this frequency + 0: no polling (default) + + threadirqs [KNL] + Force threading of all interrupt handlers except those + marked explicitly IRQF_NO_THREAD. + + tmem [KNL,XEN] + Enable the Transcendent memory driver if built-in. + + tmem.cleancache=0|1 [KNL, XEN] + Default is on (1). Disable the usage of the cleancache + API to send anonymous pages to the hypervisor. + + tmem.frontswap=0|1 [KNL, XEN] + Default is on (1). Disable the usage of the frontswap + API to send swap pages to the hypervisor. If disabled + the selfballooning and selfshrinking are force disabled. + + tmem.selfballooning=0|1 [KNL, XEN] + Default is on (1). Disable the driving of swap pages + to the hypervisor. + + tmem.selfshrinking=0|1 [KNL, XEN] + Default is on (1). Partial swapoff that immediately + transfers pages from Xen hypervisor back to the + kernel based on different criteria. + + topology= [S390] + Format: {off | on} + Specify if the kernel should make use of the cpu + topology information if the hardware supports this. + The scheduler will make use of this information and + e.g. base its process migration decisions on it. + Default is on. + + topology_updates= [KNL, PPC, NUMA] + Format: {off} + Specify if the kernel should ignore (off) + topology updates sent by the hypervisor to this + LPAR. + + tp720= [HW,PS2] + + tpm_suspend_pcr=[HW,TPM] + Format: integer pcr id + Specify that at suspend time, the tpm driver + should extend the specified pcr with zeros, + as a workaround for some chips which fail to + flush the last written pcr on TPM_SaveState. + This will guarantee that all the other pcrs + are saved. + + trace_buf_size=nn[KMG] + [FTRACE] will set tracing buffer size on each cpu. + + trace_event=[event-list] + [FTRACE] Set and start specified trace events in order + to facilitate early boot debugging. The event-list is a + comma separated list of trace events to enable. See + also Documentation/trace/events.txt + + trace_options=[option-list] + [FTRACE] Enable or disable tracer options at boot. + The option-list is a comma delimited list of options + that can be enabled or disabled just as if you were + to echo the option name into + + /sys/kernel/debug/tracing/trace_options + + For example, to enable stacktrace option (to dump the + stack trace of each event), add to the command line: + + trace_options=stacktrace + + See also Documentation/trace/ftrace.txt "trace options" + section. + + tp_printk[FTRACE] + Have the tracepoints sent to printk as well as the + tracing ring buffer. This is useful for early boot up + where the system hangs or reboots and does not give the + option for reading the tracing buffer or performing a + ftrace_dump_on_oops. + + To turn off having tracepoints sent to printk, + echo 0 > /proc/sys/kernel/tracepoint_printk + Note, echoing 1 into this file without the + tracepoint_printk kernel cmdline option has no effect. + + ** CAUTION ** + + Having tracepoints sent to printk() and activating high + frequency tracepoints such as irq or sched, can cause + the system to live lock. + + traceoff_on_warning + [FTRACE] enable this option to disable tracing when a + warning is hit. This turns off "tracing_on". Tracing can + be enabled again by echoing '1' into the "tracing_on" + file located in /sys/kernel/debug/tracing/ + + This option is useful, as it disables the trace before + the WARNING dump is called, which prevents the trace to + be filled with content caused by the warning output. + + This option can also be set at run time via the sysctl + option: kernel/traceoff_on_warning + + transparent_hugepage= + [KNL] + Format: [always|madvise|never] + Can be used to control the default behavior of the system + with respect to transparent hugepages. + See Documentation/vm/transhuge.txt for more details. + + tsc= Disable clocksource stability checks for TSC. + Format: <string> + [x86] reliable: mark tsc clocksource as reliable, this + disables clocksource verification at runtime, as well + as the stability checks done at bootup. Used to enable + high-resolution timer mode on older hardware, and in + virtualized environment. + [x86] noirqtime: Do not use TSC to do irq accounting. + Used to run time disable IRQ_TIME_ACCOUNTING on any + platforms where RDTSC is slow and this accounting + can add overhead. + + turbografx.map[2|3]= [HW,JOY] + TurboGraFX parallel port interface + Format: + <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> + See also Documentation/input/joystick-parport.txt + + udbg-immortal [PPC] When debugging early kernel crashes that + happen after console_init() and before a proper + console driver takes over, this boot options might + help "seeing" what's going on. + + uhash_entries= [KNL,NET] + Set number of hash buckets for UDP/UDP-Lite connections + + uhci-hcd.ignore_oc= + [USB] Ignore overcurrent events (default N). + Some badly-designed motherboards generate lots of + bogus events, for ports that aren't wired to + anything. Set this parameter to avoid log spamming. + Note that genuine overcurrent events won't be + reported either. + + unknown_nmi_panic + [X86] Cause panic on unknown NMI. + + usbcore.authorized_default= + [USB] Default USB device authorization: + (default -1 = authorized except for wireless USB, + 0 = not authorized, 1 = authorized) + + usbcore.autosuspend= + [USB] The autosuspend time delay (in seconds) used + for newly-detected USB devices (default 2). This + is the time required before an idle device will be + autosuspended. Devices for which the delay is set + to a negative value won't be autosuspended at all. + + usbcore.usbfs_snoop= + [USB] Set to log all usbfs traffic (default 0 = off). + + usbcore.usbfs_snoop_max= + [USB] Maximum number of bytes to snoop in each URB + (default = 65536). + + usbcore.blinkenlights= + [USB] Set to cycle leds on hubs (default 0 = off). + + usbcore.old_scheme_first= + [USB] Start with the old device initialization + scheme (default 0 = off). + + usbcore.usbfs_memory_mb= + [USB] Memory limit (in MB) for buffers allocated by + usbfs (default = 16, 0 = max = 2047). + + usbcore.use_both_schemes= + [USB] Try the other device initialization scheme + if the first one fails (default 1 = enabled). + + usbcore.initial_descriptor_timeout= + [USB] Specifies timeout for the initial 64-byte + USB_REQ_GET_DESCRIPTOR request in milliseconds + (default 5000 = 5.0 seconds). + + usbcore.nousb [USB] Disable the USB subsystem + + usbhid.mousepoll= + [USBHID] The interval which mice are to be polled at. + + usb-storage.delay_use= + [UMS] The delay in seconds before a new device is + scanned for Logical Units (default 1). + + usb-storage.quirks= + [UMS] A list of quirks entries to supplement or + override the built-in unusual_devs list. List + entries are separated by commas. Each entry has + the form VID:PID:Flags where VID and PID are Vendor + and Product ID values (4-digit hex numbers) and + Flags is a set of characters, each corresponding + to a common usb-storage quirk flag as follows: + a = SANE_SENSE (collect more than 18 bytes + of sense data); + b = BAD_SENSE (don't collect more than 18 + bytes of sense data); + c = FIX_CAPACITY (decrease the reported + device capacity by one sector); + d = NO_READ_DISC_INFO (don't use + READ_DISC_INFO command); + e = NO_READ_CAPACITY_16 (don't use + READ_CAPACITY_16 command); + f = NO_REPORT_OPCODES (don't use report opcodes + command, uas only); + g = MAX_SECTORS_240 (don't transfer more than + 240 sectors at a time, uas only); + h = CAPACITY_HEURISTICS (decrease the + reported device capacity by one + sector if the number is odd); + i = IGNORE_DEVICE (don't bind to this + device); + j = NO_REPORT_LUNS (don't use report luns + command, uas only); + l = NOT_LOCKABLE (don't try to lock and + unlock ejectable media); + m = MAX_SECTORS_64 (don't transfer more + than 64 sectors = 32 KB at a time); + n = INITIAL_READ10 (force a retry of the + initial READ(10) command); + o = CAPACITY_OK (accept the capacity + reported by the device); + p = WRITE_CACHE (the device cache is ON + by default); + r = IGNORE_RESIDUE (the device reports + bogus residue values); + s = SINGLE_LUN (the device has only one + Logical Unit); + t = NO_ATA_1X (don't allow ATA(12) and ATA(16) + commands, uas only); + u = IGNORE_UAS (don't bind to the uas driver); + w = NO_WP_DETECT (don't test whether the + medium is write-protected). + y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE + even if the device claims no cache) + Example: quirks=0419:aaf5:rl,0421:0433:rc + + user_debug= [KNL,ARM] + Format: <int> + See arch/arm/Kconfig.debug help text. + 1 - undefined instruction events + 2 - system calls + 4 - invalid data aborts + 8 - SIGSEGV faults + 16 - SIGBUS faults + Example: user_debug=31 + + userpte= + [X86] Flags controlling user PTE allocations. + + nohigh = do not allocate PTE pages in + HIGHMEM regardless of setting + of CONFIG_HIGHPTE. + + vdso= [X86,SH] + On X86_32, this is an alias for vdso32=. Otherwise: + + vdso=1: enable VDSO (the default) + vdso=0: disable VDSO mapping + + vdso32= [X86] Control the 32-bit vDSO + vdso32=1: enable 32-bit VDSO + vdso32=0 or vdso32=2: disable 32-bit VDSO + + See the help text for CONFIG_COMPAT_VDSO for more + details. If CONFIG_COMPAT_VDSO is set, the default is + vdso32=0; otherwise, the default is vdso32=1. + + For compatibility with older kernels, vdso32=2 is an + alias for vdso32=0. + + Try vdso32=0 if you encounter an error that says: + dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! + + vector= [IA-64,SMP] + vector=percpu: enable percpu vector domain + + video= [FB] Frame buffer configuration + See Documentation/fb/modedb.txt. + + video.brightness_switch_enabled= [0,1] + If set to 1, on receiving an ACPI notify event + generated by hotkey, video driver will adjust brightness + level and then send out the event to user space through + the allocated input device; If set to 0, video driver + will only send out the event without touching backlight + brightness level. + default: 1 + + virtio_mmio.device= + [VMMIO] Memory mapped virtio (platform) device. + + <size>@<baseaddr>:<irq>[:<id>] + where: + <size> := size (can use standard suffixes + like K, M and G) + <baseaddr> := physical base address + <irq> := interrupt number (as passed to + request_irq()) + <id> := (optional) platform device id + example: + virtio_mmio.device=1K@0x100b0000:48:7 + + Can be used multiple times for multiple devices. + + vga= [BOOT,X86-32] Select a particular video mode + See Documentation/x86/boot.txt and + Documentation/svga.txt. + Use vga=ask for menu. + This is actually a boot loader parameter; the value is + passed to the kernel using a special protocol. + + vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact + size of <nn>. This can be used to increase the + minimum size (128MB on x86). It can also be used to + decrease the size and leave more room for directly + mapped kernel RAM. + + vmhalt= [KNL,S390] Perform z/VM CP command after system halt. + Format: <command> + + vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. + Format: <command> + + vmpoff= [KNL,S390] Perform z/VM CP command after power off. + Format: <command> + + vsyscall= [X86-64] + Controls the behavior of vsyscalls (i.e. calls to + fixed addresses of 0xffffffffff600x00 from legacy + code). Most statically-linked binaries and older + versions of glibc use these calls. Because these + functions are at fixed addresses, they make nice + targets for exploits that can control RIP. + + emulate [default] Vsyscalls turn into traps and are + emulated reasonably safely. + + native Vsyscalls are native syscall instructions. + This is a little bit faster than trapping + and makes a few dynamic recompilers work + better than they would in emulation mode. + It also makes exploits much easier to write. + + none Vsyscalls don't work at all. This makes + them quite hard to use for exploits but + might break your system. + + vt.color= [VT] Default text color. + Format: 0xYX, X = foreground, Y = background. + Default: 0x07 = light gray on black. + + vt.cur_default= [VT] Default cursor shape. + Format: 0xCCBBAA, where AA, BB, and CC are the same as + the parameters of the <Esc>[?A;B;Cc escape sequence; + see VGA-softcursor.txt. Default: 2 = underline. + + vt.default_blu= [VT] + Format: <blue0>,<blue1>,<blue2>,...,<blue15> + Change the default blue palette of the console. + This is a 16-member array composed of values + ranging from 0-255. + + vt.default_grn= [VT] + Format: <green0>,<green1>,<green2>,...,<green15> + Change the default green palette of the console. + This is a 16-member array composed of values + ranging from 0-255. + + vt.default_red= [VT] + Format: <red0>,<red1>,<red2>,...,<red15> + Change the default red palette of the console. + This is a 16-member array composed of values + ranging from 0-255. + + vt.default_utf8= + [VT] + Format=<0|1> + Set system-wide default UTF-8 mode for all tty's. + Default is 1, i.e. UTF-8 mode is enabled for all + newly opened terminals. + + vt.global_cursor_default= + [VT] + Format=<-1|0|1> + Set system-wide default for whether a cursor + is shown on new VTs. Default is -1, + i.e. cursors will be created by default unless + overridden by individual drivers. 0 will hide + cursors, 1 will display them. + + vt.italic= [VT] Default color for italic text; 0-15. + Default: 2 = green. + + vt.underline= [VT] Default color for underlined text; 0-15. + Default: 3 = cyan. + + watchdog timers [HW,WDT] For information on watchdog timers, + see Documentation/watchdog/watchdog-parameters.txt + or other driver-specific files in the + Documentation/watchdog/ directory. + + workqueue.watchdog_thresh= + If CONFIG_WQ_WATCHDOG is configured, workqueue can + warn stall conditions and dump internal state to + help debugging. 0 disables workqueue stall + detection; otherwise, it's the stall threshold + duration in seconds. The default value is 30 and + it can be updated at runtime by writing to the + corresponding sysfs file. + + workqueue.disable_numa + By default, all work items queued to unbound + workqueues are affine to the NUMA nodes they're + issued on, which results in better behavior in + general. If NUMA affinity needs to be disabled for + whatever reason, this option can be used. Note + that this also can be controlled per-workqueue for + workqueues visible under /sys/bus/workqueue/. + + workqueue.power_efficient + Per-cpu workqueues are generally preferred because + they show better performance thanks to cache + locality; unfortunately, per-cpu workqueues tend to + be more power hungry than unbound workqueues. + + Enabling this makes the per-cpu workqueues which + were observed to contribute significantly to power + consumption unbound, leading to measurably lower + power usage at the cost of small performance + overhead. + + The default value of this parameter is determined by + the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT. + + workqueue.debug_force_rr_cpu + Workqueue used to implicitly guarantee that work + items queued without explicit CPU specified are put + on the local CPU. This guarantee is no longer true + and while local CPU is still preferred work items + may be put on foreign CPUs. This debug option + forces round-robin CPU selection to flush out + usages which depend on the now broken guarantee. + When enabled, memory and cache locality will be + impacted. + + x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of + default x2apic cluster mode on platforms + supporting x2apic. + + x86_intel_mid_timer= [X86-32,APBT] + Choose timer option for x86 Intel MID platform. + Two valid options are apbt timer only and lapic timer + plus one apbt timer for broadcast timer. + x86_intel_mid_timer=apbt_only | lapic_and_apbt + + xen_512gb_limit [KNL,X86-64,XEN] + Restricts the kernel running paravirtualized under Xen + to use only up to 512 GB of RAM. The reason to do so is + crash analysis tools and Xen tools for doing domain + save/restore/migration must be enabled to handle larger + domains. + + xen_emul_unplug= [HW,X86,XEN] + Unplug Xen emulated devices + Format: [unplug0,][unplug1] + ide-disks -- unplug primary master IDE devices + aux-ide-disks -- unplug non-primary-master IDE devices + nics -- unplug network devices + all -- unplug all emulated devices (NICs and IDE disks) + unnecessary -- unplugging emulated devices is + unnecessary even if the host did not respond to + the unplug protocol + never -- do not unplug even if version check succeeds + + xen_nopvspin [X86,XEN] + Disables the ticketlock slowpath using Xen PV + optimizations. + + xen_nopv [X86] + Disables the PV optimizations forcing the HVM guest to + run as generic HVM guest with no PV drivers. + + xirc2ps_cs= [NET,PCMCIA] + Format: + <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst new file mode 100644 index 000000000000..e449fb5f277c --- /dev/null +++ b/Documentation/admin-guide/md.rst @@ -0,0 +1,727 @@ +RAID arrays +=========== + +Boot time assembly of RAID arrays +--------------------------------- + +Tools that manage md devices can be found at + http://www.kernel.org/pub/linux/utils/raid/ + + +You can boot with your md device with the following kernel command +lines: + +for old raid arrays without persistent superblocks:: + + md=<md device no.>,<raid level>,<chunk size factor>,<fault level>,dev0,dev1,...,devn + +for raid arrays with persistent superblocks:: + + md=<md device no.>,dev0,dev1,...,devn + +or, to assemble a partitionable array:: + + md=d<md device no.>,dev0,dev1,...,devn + +``md device no.`` ++++++++++++++++++ + +The number of the md device + +================= ========= +``md device no.`` device +================= ========= + 0 md0 + 1 md1 + 2 md2 + 3 md3 + 4 md4 +================= ========= + +``raid level`` +++++++++++++++ + +level of the RAID array + +=============== ============= +``raid level`` level +=============== ============= +-1 linear mode +0 striped mode +=============== ============= + +other modes are only supported with persistent super blocks + +``chunk size factor`` ++++++++++++++++++++++ + +(raid-0 and raid-1 only) + +Set the chunk size as 4k << n. + +``fault level`` ++++++++++++++++ + +Totally ignored + +``dev0`` to ``devn`` +++++++++++++++++++++ + +e.g. ``/dev/hda1``, ``/dev/hdc1``, ``/dev/sda1``, ``/dev/sdb1`` + +A possible loadlin line (Harald Hoyer <HarryH@Royal.Net>) looks like this:: + + e:\loadlin\loadlin e:\zimage root=/dev/md0 md=0,0,4,0,/dev/hdb2,/dev/hdc3 ro + + +Boot time autodetection of RAID arrays +-------------------------------------- + +When md is compiled into the kernel (not as module), partitions of +type 0xfd are scanned and automatically assembled into RAID arrays. +This autodetection may be suppressed with the kernel parameter +``raid=noautodetect``. As of kernel 2.6.9, only drives with a type 0 +superblock can be autodetected and run at boot time. + +The kernel parameter ``raid=partitionable`` (or ``raid=part``) means +that all auto-detected arrays are assembled as partitionable. + +Boot time assembly of degraded/dirty arrays +------------------------------------------- + +If a raid5 or raid6 array is both dirty and degraded, it could have +undetectable data corruption. This is because the fact that it is +``dirty`` means that the parity cannot be trusted, and the fact that it +is degraded means that some datablocks are missing and cannot reliably +be reconstructed (due to no parity). + +For this reason, md will normally refuse to start such an array. This +requires the sysadmin to take action to explicitly start the array +despite possible corruption. This is normally done with:: + + mdadm --assemble --force .... + +This option is not really available if the array has the root +filesystem on it. In order to support this booting from such an +array, md supports a module parameter ``start_dirty_degraded`` which, +when set to 1, bypassed the checks and will allows dirty degraded +arrays to be started. + +So, to boot with a root filesystem of a dirty degraded raid 5 or 6, use:: + + md-mod.start_dirty_degraded=1 + + +Superblock formats +------------------ + +The md driver can support a variety of different superblock formats. +Currently, it supports superblock formats ``0.90.0`` and the ``md-1`` format +introduced in the 2.5 development series. + +The kernel will autodetect which format superblock is being used. + +Superblock format ``0`` is treated differently to others for legacy +reasons - it is the original superblock format. + + +General Rules - apply for all superblock formats +------------------------------------------------ + +An array is ``created`` by writing appropriate superblocks to all +devices. + +It is ``assembled`` by associating each of these devices with an +particular md virtual device. Once it is completely assembled, it can +be accessed. + +An array should be created by a user-space tool. This will write +superblocks to all devices. It will usually mark the array as +``unclean``, or with some devices missing so that the kernel md driver +can create appropriate redundancy (copying in raid 1, parity +calculation in raid 4/5). + +When an array is assembled, it is first initialized with the +SET_ARRAY_INFO ioctl. This contains, in particular, a major and minor +version number. The major version number selects which superblock +format is to be used. The minor number might be used to tune handling +of the format, such as suggesting where on each device to look for the +superblock. + +Then each device is added using the ADD_NEW_DISK ioctl. This +provides, in particular, a major and minor number identifying the +device to add. + +The array is started with the RUN_ARRAY ioctl. + +Once started, new devices can be added. They should have an +appropriate superblock written to them, and then be passed in with +ADD_NEW_DISK. + +Devices that have failed or are not yet active can be detached from an +array using HOT_REMOVE_DISK. + + +Specific Rules that apply to format-0 super block arrays, and arrays with no superblock (non-persistent) +-------------------------------------------------------------------------------------------------------- + +An array can be ``created`` by describing the array (level, chunksize +etc) in a SET_ARRAY_INFO ioctl. This must have ``major_version==0`` and +``raid_disks != 0``. + +Then uninitialized devices can be added with ADD_NEW_DISK. The +structure passed to ADD_NEW_DISK must specify the state of the device +and its role in the array. + +Once started with RUN_ARRAY, uninitialized spares can be added with +HOT_ADD_DISK. + + +MD devices in sysfs +------------------- + +md devices appear in sysfs (``/sys``) as regular block devices, +e.g.:: + + /sys/block/md0 + +Each ``md`` device will contain a subdirectory called ``md`` which +contains further md-specific information about the device. + +All md devices contain: + + level + a text file indicating the ``raid level``. e.g. raid0, raid1, + raid5, linear, multipath, faulty. + If no raid level has been set yet (array is still being + assembled), the value will reflect whatever has been written + to it, which may be a name like the above, or may be a number + such as ``0``, ``5``, etc. + + raid_disks + a text file with a simple number indicating the number of devices + in a fully functional array. If this is not yet known, the file + will be empty. If an array is being resized this will contain + the new number of devices. + Some raid levels allow this value to be set while the array is + active. This will reconfigure the array. Otherwise it can only + be set while assembling an array. + A change to this attribute will not be permitted if it would + reduce the size of the array. To reduce the number of drives + in an e.g. raid5, the array size must first be reduced by + setting the ``array_size`` attribute. + + chunk_size + This is the size in bytes for ``chunks`` and is only relevant to + raid levels that involve striping (0,4,5,6,10). The address space + of the array is conceptually divided into chunks and consecutive + chunks are striped onto neighbouring devices. + The size should be at least PAGE_SIZE (4k) and should be a power + of 2. This can only be set while assembling an array + + layout + The ``layout`` for the array for the particular level. This is + simply a number that is interpretted differently by different + levels. It can be written while assembling an array. + + array_size + This can be used to artificially constrain the available space in + the array to be less than is actually available on the combined + devices. Writing a number (in Kilobytes) which is less than + the available size will set the size. Any reconfiguration of the + array (e.g. adding devices) will not cause the size to change. + Writing the word ``default`` will cause the effective size of the + array to be whatever size is actually available based on + ``level``, ``chunk_size`` and ``component_size``. + + This can be used to reduce the size of the array before reducing + the number of devices in a raid4/5/6, or to support external + metadata formats which mandate such clipping. + + reshape_position + This is either ``none`` or a sector number within the devices of + the array where ``reshape`` is up to. If this is set, the three + attributes mentioned above (raid_disks, chunk_size, layout) can + potentially have 2 values, an old and a new value. If these + values differ, reading the attribute returns:: + + new (old) + + and writing will effect the ``new`` value, leaving the ``old`` + unchanged. + + component_size + For arrays with data redundancy (i.e. not raid0, linear, faulty, + multipath), all components must be the same size - or at least + there must a size that they all provide space for. This is a key + part or the geometry of the array. It is measured in sectors + and can be read from here. Writing to this value may resize + the array if the personality supports it (raid1, raid5, raid6), + and if the component drives are large enough. + + metadata_version + This indicates the format that is being used to record metadata + about the array. It can be 0.90 (traditional format), 1.0, 1.1, + 1.2 (newer format in varying locations) or ``none`` indicating that + the kernel isn't managing metadata at all. + Alternately it can be ``external:`` followed by a string which + is set by user-space. This indicates that metadata is managed + by a user-space program. Any device failure or other event that + requires a metadata update will cause array activity to be + suspended until the event is acknowledged. + + resync_start + The point at which resync should start. If no resync is needed, + this will be a very large number (or ``none`` since 2.6.30-rc1). At + array creation it will default to 0, though starting the array as + ``clean`` will set it much larger. + + new_dev + This file can be written but not read. The value written should + be a block device number as major:minor. e.g. 8:0 + This will cause that device to be attached to the array, if it is + available. It will then appear at md/dev-XXX (depending on the + name of the device) and further configuration is then possible. + + safe_mode_delay + When an md array has seen no write requests for a certain period + of time, it will be marked as ``clean``. When another write + request arrives, the array is marked as ``dirty`` before the write + commences. This is known as ``safe_mode``. + The ``certain period`` is controlled by this file which stores the + period as a number of seconds. The default is 200msec (0.200). + Writing a value of 0 disables safemode. + + array_state + This file contains a single word which describes the current + state of the array. In many cases, the state can be set by + writing the word for the desired state, however some states + cannot be explicitly set, and some transitions are not allowed. + + Select/poll works on this file. All changes except between + Active_idle and active (which can be frequent and are not + very interesting) are notified. active->active_idle is + reported if the metadata is externally managed. + + clear + No devices, no size, no level + + Writing is equivalent to STOP_ARRAY ioctl + + inactive + May have some settings, but array is not active + all IO results in error + + When written, doesn't tear down array, but just stops it + + suspended (not supported yet) + All IO requests will block. The array can be reconfigured. + + Writing this, if accepted, will block until array is quiessent + + readonly + no resync can happen. no superblocks get written. + + Write requests fail + + read-auto + like readonly, but behaves like ``clean`` on a write request. + + clean + no pending writes, but otherwise active. + + When written to inactive array, starts without resync + + If a write request arrives then + if metadata is known, mark ``dirty`` and switch to ``active``. + if not known, block and switch to write-pending + + If written to an active array that has pending writes, then fails. + active + fully active: IO and resync can be happening. + When written to inactive array, starts with resync + + write-pending + clean, but writes are blocked waiting for ``active`` to be written. + + active-idle + like active, but no writes have been seen for a while (safe_mode_delay). + + bitmap/location + This indicates where the write-intent bitmap for the array is + stored. + + It can be one of ``none``, ``file`` or ``[+-]N``. + ``file`` may later be extended to ``file:/file/name`` + ``[+-]N`` means that many sectors from the start of the metadata. + + This is replicated on all devices. For arrays with externally + managed metadata, the offset is from the beginning of the + device. + + bitmap/chunksize + The size, in bytes, of the chunk which will be represented by a + single bit. For RAID456, it is a portion of an individual + device. For RAID10, it is a portion of the array. For RAID1, it + is both (they come to the same thing). + + bitmap/time_base + The time, in seconds, between looking for bits in the bitmap to + be cleared. In the current implementation, a bit will be cleared + between 2 and 3 times ``time_base`` after all the covered blocks + are known to be in-sync. + + bitmap/backlog + When write-mostly devices are active in a RAID1, write requests + to those devices proceed in the background - the filesystem (or + other user of the device) does not have to wait for them. + ``backlog`` sets a limit on the number of concurrent background + writes. If there are more than this, new writes will by + synchronous. + + bitmap/metadata + This can be either ``internal`` or ``external``. + + ``internal`` + is the default and means the metadata for the bitmap + is stored in the first 256 bytes of the allocated space and is + managed by the md module. + + ``external`` + means that bitmap metadata is managed externally to + the kernel (i.e. by some userspace program) + + bitmap/can_clear + This is either ``true`` or ``false``. If ``true``, then bits in the + bitmap will be cleared when the corresponding blocks are thought + to be in-sync. If ``false``, bits will never be cleared. + This is automatically set to ``false`` if a write happens on a + degraded array, or if the array becomes degraded during a write. + When metadata is managed externally, it should be set to true + once the array becomes non-degraded, and this fact has been + recorded in the metadata. + + + + +As component devices are added to an md array, they appear in the ``md`` +directory as new directories named:: + + dev-XXX + +where ``XXX`` is a name that the kernel knows for the device, e.g. hdb1. +Each directory contains: + + block + a symlink to the block device in /sys/block, e.g.:: + + /sys/block/md0/md/dev-hdb1/block -> ../../../../block/hdb/hdb1 + + super + A file containing an image of the superblock read from, or + written to, that device. + + state + A file recording the current state of the device in the array + which can be a comma separated list of: + + faulty + device has been kicked from active use due to + a detected fault, or it has unacknowledged bad + blocks + + in_sync + device is a fully in-sync member of the array + + writemostly + device will only be subject to read + requests if there are no other options. + + This applies only to raid1 arrays. + + blocked + device has failed, and the failure hasn't been + acknowledged yet by the metadata handler. + + Writes that would write to this device if + it were not faulty are blocked. + + spare + device is working, but not a full member. + + This includes spares that are in the process + of being recovered to + + write_error + device has ever seen a write error. + + want_replacement + device is (mostly) working but probably + should be replaced, either due to errors or + due to user request. + + replacement + device is a replacement for another active + device with same raid_disk. + + + This list may grow in future. + + This can be written to. + + Writing ``faulty`` simulates a failure on the device. + + Writing ``remove`` removes the device from the array. + + Writing ``writemostly`` sets the writemostly flag. + + Writing ``-writemostly`` clears the writemostly flag. + + Writing ``blocked`` sets the ``blocked`` flag. + + Writing ``-blocked`` clears the ``blocked`` flags and allows writes + to complete and possibly simulates an error. + + Writing ``in_sync`` sets the in_sync flag. + + Writing ``write_error`` sets writeerrorseen flag. + + Writing ``-write_error`` clears writeerrorseen flag. + + Writing ``want_replacement`` is allowed at any time except to a + replacement device or a spare. It sets the flag. + + Writing ``-want_replacement`` is allowed at any time. It clears + the flag. + + Writing ``replacement`` or ``-replacement`` is only allowed before + starting the array. It sets or clears the flag. + + + This file responds to select/poll. Any change to ``faulty`` + or ``blocked`` causes an event. + + errors + An approximate count of read errors that have been detected on + this device but have not caused the device to be evicted from + the array (either because they were corrected or because they + happened while the array was read-only). When using version-1 + metadata, this value persists across restarts of the array. + + This value can be written while assembling an array thus + providing an ongoing count for arrays with metadata managed by + userspace. + + slot + This gives the role that the device has in the array. It will + either be ``none`` if the device is not active in the array + (i.e. is a spare or has failed) or an integer less than the + ``raid_disks`` number for the array indicating which position + it currently fills. This can only be set while assembling an + array. A device for which this is set is assumed to be working. + + offset + This gives the location in the device (in sectors from the + start) where data from the array will be stored. Any part of + the device before this offset is not touched, unless it is + used for storing metadata (Formats 1.1 and 1.2). + + size + The amount of the device, after the offset, that can be used + for storage of data. This will normally be the same as the + component_size. This can be written while assembling an + array. If a value less than the current component_size is + written, it will be rejected. + + recovery_start + When the device is not ``in_sync``, this records the number of + sectors from the start of the device which are known to be + correct. This is normally zero, but during a recovery + operation it will steadily increase, and if the recovery is + interrupted, restoring this value can cause recovery to + avoid repeating the earlier blocks. With v1.x metadata, this + value is saved and restored automatically. + + This can be set whenever the device is not an active member of + the array, either before the array is activated, or before + the ``slot`` is set. + + Setting this to ``none`` is equivalent to setting ``in_sync``. + Setting to any other value also clears the ``in_sync`` flag. + + bad_blocks + This gives the list of all known bad blocks in the form of + start address and length (in sectors respectively). If output + is too big to fit in a page, it will be truncated. Writing + ``sector length`` to this file adds new acknowledged (i.e. + recorded to disk safely) bad blocks. + + unacknowledged_bad_blocks + This gives the list of known-but-not-yet-saved-to-disk bad + blocks in the same form of ``bad_blocks``. If output is too big + to fit in a page, it will be truncated. Writing to this file + adds bad blocks without acknowledging them. This is largely + for testing. + + + +An active md device will also contain an entry for each active device +in the array. These are named:: + + rdNN + +where ``NN`` is the position in the array, starting from 0. +So for a 3 drive array there will be rd0, rd1, rd2. +These are symbolic links to the appropriate ``dev-XXX`` entry. +Thus, for example:: + + cat /sys/block/md*/md/rd*/state + +will show ``in_sync`` on every line. + + + +Active md devices for levels that support data redundancy (1,4,5,6,10) +also have + + sync_action + a text file that can be used to monitor and control the rebuild + process. It contains one word which can be one of: + + resync + redundancy is being recalculated after unclean + shutdown or creation + + recover + a hot spare is being built to replace a + failed/missing device + + idle + nothing is happening + check + A full check of redundancy was requested and is + happening. This reads all blocks and checks + them. A repair may also happen for some raid + levels. + + repair + A full check and repair is happening. This is + similar to ``resync``, but was requested by the + user, and the write-intent bitmap is NOT used to + optimise the process. + + This file is writable, and each of the strings that could be + read are meaningful for writing. + + ``idle`` will stop an active resync/recovery etc. There is no + guarantee that another resync/recovery may not be automatically + started again, though some event will be needed to trigger + this. + + ``resync`` or ``recovery`` can be used to restart the + corresponding operation if it was stopped with ``idle``. + + ``check`` and ``repair`` will start the appropriate process + providing the current state is ``idle``. + + This file responds to select/poll. Any important change in the value + triggers a poll event. Sometimes the value will briefly be + ``recover`` if a recovery seems to be needed, but cannot be + achieved. In that case, the transition to ``recover`` isn't + notified, but the transition away is. + + degraded + This contains a count of the number of devices by which the + arrays is degraded. So an optimal array will show ``0``. A + single failed/missing drive will show ``1``, etc. + + This file responds to select/poll, any increase or decrease + in the count of missing devices will trigger an event. + + mismatch_count + When performing ``check`` and ``repair``, and possibly when + performing ``resync``, md will count the number of errors that are + found. The count in ``mismatch_cnt`` is the number of sectors + that were re-written, or (for ``check``) would have been + re-written. As most raid levels work in units of pages rather + than sectors, this may be larger than the number of actual errors + by a factor of the number of sectors in a page. + + bitmap_set_bits + If the array has a write-intent bitmap, then writing to this + attribute can set bits in the bitmap, indicating that a resync + would need to check the corresponding blocks. Either individual + numbers or start-end pairs can be written. Multiple numbers + can be separated by a space. + + Note that the numbers are ``bit`` numbers, not ``block`` numbers. + They should be scaled by the bitmap_chunksize. + + sync_speed_min, sync_speed_max + This are similar to ``/proc/sys/dev/raid/speed_limit_{min,max}`` + however they only apply to the particular array. + + If no value has been written to these, or if the word ``system`` + is written, then the system-wide value is used. If a value, + in kibibytes-per-second is written, then it is used. + + When the files are read, they show the currently active value + followed by ``(local)`` or ``(system)`` depending on whether it is + a locally set or system-wide value. + + sync_completed + This shows the number of sectors that have been completed of + whatever the current sync_action is, followed by the number of + sectors in total that could need to be processed. The two + numbers are separated by a ``/`` thus effectively showing one + value, a fraction of the process that is complete. + + A ``select`` on this attribute will return when resync completes, + when it reaches the current sync_max (below) and possibly at + other times. + + sync_speed + This shows the current actual speed, in K/sec, of the current + sync_action. It is averaged over the last 30 seconds. + + suspend_lo, suspend_hi + The two values, given as numbers of sectors, indicate a range + within the array where IO will be blocked. This is currently + only supported for raid4/5/6. + + sync_min, sync_max + The two values, given as numbers of sectors, indicate a range + within the array where ``check``/``repair`` will operate. Must be + a multiple of chunk_size. When it reaches ``sync_max`` it will + pause, rather than complete. + You can use ``select`` or ``poll`` on ``sync_completed`` to wait for + that number to reach sync_max. Then you can either increase + ``sync_max``, or can write ``idle`` to ``sync_action``. + + The value of ``max`` for ``sync_max`` effectively disables the limit. + When a resync is active, the value can only ever be increased, + never decreased. + The value of ``0`` is the minimum for ``sync_min``. + + + +Each active md device may also have attributes specific to the +personality module that manages it. +These are specific to the implementation of the module and could +change substantially if the implementation changes. + +These currently include: + + stripe_cache_size (currently raid5 only) + number of entries in the stripe cache. This is writable, but + there are upper and lower limits (32768, 17). Default is 256. + + strip_cache_active (currently raid5 only) + number of active entries in the stripe cache + + preread_bypass_threshold (currently raid5 only) + number of times a stripe requiring preread will be bypassed by + a stripe that does not require preread. For fairness defaults + to 1. Setting this to 0 disables bypass accounting and + requires preread stripes to wait until all full-width stripe- + writes are complete. Valid values are 0 to stripe_cache_size. diff --git a/Documentation/admin-guide/module-signing.rst b/Documentation/admin-guide/module-signing.rst new file mode 100644 index 000000000000..27e59498b487 --- /dev/null +++ b/Documentation/admin-guide/module-signing.rst @@ -0,0 +1,285 @@ +Kernel module signing facility +------------------------------ + +.. CONTENTS +.. +.. - Overview. +.. - Configuring module signing. +.. - Generating signing keys. +.. - Public keys in the kernel. +.. - Manually signing modules. +.. - Signed modules and stripping. +.. - Loading signed modules. +.. - Non-valid signatures and unsigned modules. +.. - Administering/protecting the private key. + + +======== +Overview +======== + +The kernel module signing facility cryptographically signs modules during +installation and then checks the signature upon loading the module. This +allows increased kernel security by disallowing the loading of unsigned modules +or modules signed with an invalid key. Module signing increases security by +making it harder to load a malicious module into the kernel. The module +signature checking is done by the kernel so that it is not necessary to have +trusted userspace bits. + +This facility uses X.509 ITU-T standard certificates to encode the public keys +involved. The signatures are not themselves encoded in any industrial standard +type. The facility currently only supports the RSA public key encryption +standard (though it is pluggable and permits others to be used). The possible +hash algorithms that can be used are SHA-1, SHA-224, SHA-256, SHA-384, and +SHA-512 (the algorithm is selected by data in the signature). + + +========================== +Configuring module signing +========================== + +The module signing facility is enabled by going to the +:menuselection:`Enable Loadable Module Support` section of +the kernel configuration and turning on:: + + CONFIG_MODULE_SIG "Module signature verification" + +This has a number of options available: + + (1) :menuselection:`Require modules to be validly signed` + (``CONFIG_MODULE_SIG_FORCE``) + + This specifies how the kernel should deal with a module that has a + signature for which the key is not known or a module that is unsigned. + + If this is off (ie. "permissive"), then modules for which the key is not + available and modules that are unsigned are permitted, but the kernel will + be marked as being tainted, and the concerned modules will be marked as + tainted, shown with the character 'E'. + + If this is on (ie. "restrictive"), only modules that have a valid + signature that can be verified by a public key in the kernel's possession + will be loaded. All other modules will generate an error. + + Irrespective of the setting here, if the module has a signature block that + cannot be parsed, it will be rejected out of hand. + + + (2) :menuselection:`Automatically sign all modules` + (``CONFIG_MODULE_SIG_ALL``) + + If this is on then modules will be automatically signed during the + modules_install phase of a build. If this is off, then the modules must + be signed manually using:: + + scripts/sign-file + + + (3) :menuselection:`Which hash algorithm should modules be signed with?` + + This presents a choice of which hash algorithm the installation phase will + sign the modules with: + + =============================== ========================================== + ``CONFIG_MODULE_SIG_SHA1`` :menuselection:`Sign modules with SHA-1` + ``CONFIG_MODULE_SIG_SHA224`` :menuselection:`Sign modules with SHA-224` + ``CONFIG_MODULE_SIG_SHA256`` :menuselection:`Sign modules with SHA-256` + ``CONFIG_MODULE_SIG_SHA384`` :menuselection:`Sign modules with SHA-384` + ``CONFIG_MODULE_SIG_SHA512`` :menuselection:`Sign modules with SHA-512` + =============================== ========================================== + + The algorithm selected here will also be built into the kernel (rather + than being a module) so that modules signed with that algorithm can have + their signatures checked without causing a dependency loop. + + + (4) :menuselection:`File name or PKCS#11 URI of module signing key` + (``CONFIG_MODULE_SIG_KEY``) + + Setting this option to something other than its default of + ``certs/signing_key.pem`` will disable the autogeneration of signing keys + and allow the kernel modules to be signed with a key of your choosing. + The string provided should identify a file containing both a private key + and its corresponding X.509 certificate in PEM form, or — on systems where + the OpenSSL ENGINE_pkcs11 is functional — a PKCS#11 URI as defined by + RFC7512. In the latter case, the PKCS#11 URI should reference both a + certificate and a private key. + + If the PEM file containing the private key is encrypted, or if the + PKCS#11 token requries a PIN, this can be provided at build time by + means of the ``KBUILD_SIGN_PIN`` variable. + + + (5) :menuselection:`Additional X.509 keys for default system keyring` + (``CONFIG_SYSTEM_TRUSTED_KEYS``) + + This option can be set to the filename of a PEM-encoded file containing + additional certificates which will be included in the system keyring by + default. + +Note that enabling module signing adds a dependency on the OpenSSL devel +packages to the kernel build processes for the tool that does the signing. + + +======================= +Generating signing keys +======================= + +Cryptographic keypairs are required to generate and check signatures. A +private key is used to generate a signature and the corresponding public key is +used to check it. The private key is only needed during the build, after which +it can be deleted or stored securely. The public key gets built into the +kernel so that it can be used to check the signatures as the modules are +loaded. + +Under normal conditions, when ``CONFIG_MODULE_SIG_KEY`` is unchanged from its +default, the kernel build will automatically generate a new keypair using +openssl if one does not exist in the file:: + + certs/signing_key.pem + +during the building of vmlinux (the public part of the key needs to be built +into vmlinux) using parameters in the:: + + certs/x509.genkey + +file (which is also generated if it does not already exist). + +It is strongly recommended that you provide your own x509.genkey file. + +Most notably, in the x509.genkey file, the req_distinguished_name section +should be altered from the default:: + + [ req_distinguished_name ] + #O = Unspecified company + CN = Build time autogenerated kernel key + #emailAddress = unspecified.user@unspecified.company + +The generated RSA key size can also be set with:: + + [ req ] + default_bits = 4096 + + +It is also possible to manually generate the key private/public files using the +x509.genkey key generation configuration file in the root node of the Linux +kernel sources tree and the openssl command. The following is an example to +generate the public/private key files:: + + openssl req -new -nodes -utf8 -sha256 -days 36500 -batch -x509 \ + -config x509.genkey -outform PEM -out kernel_key.pem \ + -keyout kernel_key.pem + +The full pathname for the resulting kernel_key.pem file can then be specified +in the ``CONFIG_MODULE_SIG_KEY`` option, and the certificate and key therein will +be used instead of an autogenerated keypair. + + +========================= +Public keys in the kernel +========================= + +The kernel contains a ring of public keys that can be viewed by root. They're +in a keyring called ".system_keyring" that can be seen by:: + + [root@deneb ~]# cat /proc/keys + ... + 223c7853 I------ 1 perm 1f030000 0 0 keyring .system_keyring: 1 + 302d2d52 I------ 1 perm 1f010000 0 0 asymmetri Fedora kernel signing key: d69a84e6bce3d216b979e9505b3e3ef9a7118079: X509.RSA a7118079 [] + ... + +Beyond the public key generated specifically for module signing, additional +trusted certificates can be provided in a PEM-encoded file referenced by the +``CONFIG_SYSTEM_TRUSTED_KEYS`` configuration option. + +Further, the architecture code may take public keys from a hardware store and +add those in also (e.g. from the UEFI key database). + +Finally, it is possible to add additional public keys by doing:: + + keyctl padd asymmetric "" [.system_keyring-ID] <[key-file] + +e.g.:: + + keyctl padd asymmetric "" 0x223c7853 <my_public_key.x509 + +Note, however, that the kernel will only permit keys to be added to +``.system_keyring _if_`` the new key's X.509 wrapper is validly signed by a key +that is already resident in the .system_keyring at the time the key was added. + + +======================== +Manually signing modules +======================== + +To manually sign a module, use the scripts/sign-file tool available in +the Linux kernel source tree. The script requires 4 arguments: + + 1. The hash algorithm (e.g., sha256) + 2. The private key filename or PKCS#11 URI + 3. The public key filename + 4. The kernel module to be signed + +The following is an example to sign a kernel module:: + + scripts/sign-file sha512 kernel-signkey.priv \ + kernel-signkey.x509 module.ko + +The hash algorithm used does not have to match the one configured, but if it +doesn't, you should make sure that hash algorithm is either built into the +kernel or can be loaded without requiring itself. + +If the private key requires a passphrase or PIN, it can be provided in the +$KBUILD_SIGN_PIN environment variable. + + +============================ +Signed modules and stripping +============================ + +A signed module has a digital signature simply appended at the end. The string +``~Module signature appended~.`` at the end of the module's file confirms that a +signature is present but it does not confirm that the signature is valid! + +Signed modules are BRITTLE as the signature is outside of the defined ELF +container. Thus they MAY NOT be stripped once the signature is computed and +attached. Note the entire module is the signed payload, including any and all +debug information present at the time of signing. + + +====================== +Loading signed modules +====================== + +Modules are loaded with insmod, modprobe, ``init_module()`` or +``finit_module()``, exactly as for unsigned modules as no processing is +done in userspace. The signature checking is all done within the kernel. + + +========================================= +Non-valid signatures and unsigned modules +========================================= + +If ``CONFIG_MODULE_SIG_FORCE`` is enabled or module.sig_enforce=1 is supplied on +the kernel command line, the kernel will only load validly signed modules +for which it has a public key. Otherwise, it will also load modules that are +unsigned. Any module for which the kernel has a key, but which proves to have +a signature mismatch will not be permitted to load. + +Any module that has an unparseable signature will be rejected. + + +========================================= +Administering/protecting the private key +========================================= + +Since the private key is used to sign modules, viruses and malware could use +the private key to sign modules and compromise the operating system. The +private key must be either destroyed or moved to a secure location and not kept +in the root node of the kernel source tree. + +If you use the same private key to sign modules for multiple kernel +configurations, you must ensure that the module version information is +sufficient to prevent loading a module into a different kernel. Either +set ``CONFIG_MODVERSIONS=y`` or ensure that each configuration has a different +kernel release string by changing ``EXTRAVERSION`` or ``CONFIG_LOCALVERSION``. diff --git a/Documentation/admin-guide/mono.rst b/Documentation/admin-guide/mono.rst new file mode 100644 index 000000000000..cdddc099af64 --- /dev/null +++ b/Documentation/admin-guide/mono.rst @@ -0,0 +1,70 @@ +Mono(tm) Binary Kernel Support for Linux +----------------------------------------- + +To configure Linux to automatically execute Mono-based .NET binaries +(in the form of .exe files) without the need to use the mono CLR +wrapper, you can use the BINFMT_MISC kernel support. + +This will allow you to execute Mono-based .NET binaries just like any +other program after you have done the following: + +1) You MUST FIRST install the Mono CLR support, either by downloading + a binary package, a source tarball or by installing from CVS. Binary + packages for several distributions can be found at: + + http://go-mono.com/download.html + + Instructions for compiling Mono can be found at: + + http://www.go-mono.com/compiling.html + + Once the Mono CLR support has been installed, just check that + ``/usr/bin/mono`` (which could be located elsewhere, for example + ``/usr/local/bin/mono``) is working. + +2) You have to compile BINFMT_MISC either as a module or into + the kernel (``CONFIG_BINFMT_MISC``) and set it up properly. + If you choose to compile it as a module, you will have + to insert it manually with modprobe/insmod, as kmod + cannot be easily supported with binfmt_misc. + Read the file ``binfmt_misc.txt`` in this directory to know + more about the configuration process. + +3) Add the following entries to ``/etc/rc.local`` or similar script + to be run at system startup: + + .. code-block:: sh + + # Insert BINFMT_MISC module into the kernel + if [ ! -e /proc/sys/fs/binfmt_misc/register ]; then + /sbin/modprobe binfmt_misc + # Some distributions, like Fedora Core, perform + # the following command automatically when the + # binfmt_misc module is loaded into the kernel + # or during normal boot up (systemd-based systems). + # Thus, it is possible that the following line + # is not needed at all. + mount -t binfmt_misc none /proc/sys/fs/binfmt_misc + fi + + # Register support for .NET CLR binaries + if [ -e /proc/sys/fs/binfmt_misc/register ]; then + # Replace /usr/bin/mono with the correct pathname to + # the Mono CLR runtime (usually /usr/local/bin/mono + # when compiling from sources or CVS). + echo ':CLR:M::MZ::/usr/bin/mono:' > /proc/sys/fs/binfmt_misc/register + else + echo "No binfmt_misc support" + exit 1 + fi + +4) Check that ``.exe`` binaries can be ran without the need of a + wrapper script, simply by launching the ``.exe`` file directly + from a command prompt, for example:: + + /usr/bin/xsd.exe + + .. note:: + + If this fails with a permission denied error, check + that the ``.exe`` file has execute permissions. diff --git a/Documentation/admin-guide/parport.rst b/Documentation/admin-guide/parport.rst new file mode 100644 index 000000000000..ad3f9b8a11e1 --- /dev/null +++ b/Documentation/admin-guide/parport.rst @@ -0,0 +1,286 @@ +Parport ++++++++ + +The ``parport`` code provides parallel-port support under Linux. This +includes the ability to share one port between multiple device +drivers. + +You can pass parameters to the ``parport`` code to override its automatic +detection of your hardware. This is particularly useful if you want +to use IRQs, since in general these can't be autoprobed successfully. +By default IRQs are not used even if they **can** be probed. This is +because there are a lot of people using the same IRQ for their +parallel port and a sound card or network card. + +The ``parport`` code is split into two parts: generic (which deals with +port-sharing) and architecture-dependent (which deals with actually +using the port). + + +Parport as modules +================== + +If you load the `parport`` code as a module, say:: + + # insmod parport + +to load the generic ``parport`` code. You then must load the +architecture-dependent code with (for example):: + + # insmod parport_pc io=0x3bc,0x378,0x278 irq=none,7,auto + +to tell the ``parport`` code that you want three PC-style ports, one at +0x3bc with no IRQ, one at 0x378 using IRQ 7, and one at 0x278 with an +auto-detected IRQ. Currently, PC-style (``parport_pc``), Sun ``bpp``, +Amiga, Atari, and MFC3 hardware is supported. + +PCI parallel I/O card support comes from ``parport_pc``. Base I/O +addresses should not be specified for supported PCI cards since they +are automatically detected. + + +modprobe +-------- + +If you use modprobe , you will find it useful to add lines as below to a +configuration file in /etc/modprobe.d/ directory:: + + alias parport_lowlevel parport_pc + options parport_pc io=0x378,0x278 irq=7,auto + +modprobe will load ``parport_pc`` (with the options ``io=0x378,0x278 irq=7,auto``) +whenever a parallel port device driver (such as ``lp``) is loaded. + +Note that these are example lines only! You shouldn't in general need +to specify any options to ``parport_pc`` in order to be able to use a +parallel port. + + +Parport probe [optional] +------------------------ + +In 2.2 kernels there was a module called ``parport_probe``, which was used +for collecting IEEE 1284 device ID information. This has now been +enhanced and now lives with the IEEE 1284 support. When a parallel +port is detected, the devices that are connected to it are analysed, +and information is logged like this:: + + parport0: Printer, BJC-210 (Canon) + +The probe information is available from files in ``/proc/sys/dev/parport/``. + + +Parport linked into the kernel statically +========================================= + +If you compile the ``parport`` code into the kernel, then you can use +kernel boot parameters to get the same effect. Add something like the +following to your LILO command line:: + + parport=0x3bc parport=0x378,7 parport=0x278,auto,nofifo + +You can have many ``parport=...`` statements, one for each port you want +to add. Adding ``parport=0`` to the kernel command-line will disable +parport support entirely. Adding ``parport=auto`` to the kernel +command-line will make ``parport`` use any IRQ lines or DMA channels that +it auto-detects. + + +Files in /proc +============== + +If you have configured the ``/proc`` filesystem into your kernel, you will +see a new directory entry: ``/proc/sys/dev/parport``. In there will be a +directory entry for each parallel port for which parport is +configured. In each of those directories are a collection of files +describing that parallel port. + +The ``/proc/sys/dev/parport`` directory tree looks like:: + + parport + |-- default + | |-- spintime + | `-- timeslice + |-- parport0 + | |-- autoprobe + | |-- autoprobe0 + | |-- autoprobe1 + | |-- autoprobe2 + | |-- autoprobe3 + | |-- devices + | | |-- active + | | `-- lp + | | `-- timeslice + | |-- base-addr + | |-- irq + | |-- dma + | |-- modes + | `-- spintime + `-- parport1 + |-- autoprobe + |-- autoprobe0 + |-- autoprobe1 + |-- autoprobe2 + |-- autoprobe3 + |-- devices + | |-- active + | `-- ppa + | `-- timeslice + |-- base-addr + |-- irq + |-- dma + |-- modes + `-- spintime + +.. tabularcolumns:: |p{4.0cm}|p{13.5cm}| + +======================= ======================================================= +File Contents +======================= ======================================================= +``devices/active`` A list of the device drivers using that port. A "+" + will appear by the name of the device currently using + the port (it might not appear against any). The + string "none" means that there are no device drivers + using that port. + +``base-addr`` Parallel port's base address, or addresses if the port + has more than one in which case they are separated + with tabs. These values might not have any sensible + meaning for some ports. + +``irq`` Parallel port's IRQ, or -1 if none is being used. + +``dma`` Parallel port's DMA channel, or -1 if none is being + used. + +``modes`` Parallel port's hardware modes, comma-separated, + meaning: + + - PCSPP + PC-style SPP registers are available. + + - TRISTATE + Port is bidirectional. + + - COMPAT + Hardware acceleration for printers is + available and will be used. + + - EPP + Hardware acceleration for EPP protocol + is available and will be used. + + - ECP + Hardware acceleration for ECP protocol + is available and will be used. + + - DMA + DMA is available and will be used. + + Note that the current implementation will only take + advantage of COMPAT and ECP modes if it has an IRQ + line to use. + +``autoprobe`` Any IEEE-1284 device ID information that has been + acquired from the (non-IEEE 1284.3) device. + +``autoprobe[0-3]`` IEEE 1284 device ID information retrieved from + daisy-chain devices that conform to IEEE 1284.3. + +``spintime`` The number of microseconds to busy-loop while waiting + for the peripheral to respond. You might find that + adjusting this improves performance, depending on your + peripherals. This is a port-wide setting, i.e. it + applies to all devices on a particular port. + +``timeslice`` The number of milliseconds that a device driver is + allowed to keep a port claimed for. This is advisory, + and driver can ignore it if it must. + +``default/*`` The defaults for spintime and timeslice. When a new + port is registered, it picks up the default spintime. + When a new device is registered, it picks up the + default timeslice. +======================= ======================================================= + +Device drivers +============== + +Once the parport code is initialised, you can attach device drivers to +specific ports. Normally this happens automatically; if the lp driver +is loaded it will create one lp device for each port found. You can +override this, though, by using parameters either when you load the lp +driver:: + + # insmod lp parport=0,2 + +or on the LILO command line:: + + lp=parport0 lp=parport2 + +Both the above examples would inform lp that you want ``/dev/lp0`` to be +the first parallel port, and /dev/lp1 to be the **third** parallel port, +with no lp device associated with the second port (parport1). Note +that this is different to the way older kernels worked; there used to +be a static association between the I/O port address and the device +name, so ``/dev/lp0`` was always the port at 0x3bc. This is no longer the +case - if you only have one port, it will default to being ``/dev/lp0``, +regardless of base address. + +Also: + + * If you selected the IEEE 1284 support at compile time, you can say + ``lp=auto`` on the kernel command line, and lp will create devices + only for those ports that seem to have printers attached. + + * If you give PLIP the ``timid`` parameter, either with ``plip=timid`` on + the command line, or with ``insmod plip timid=1`` when using modules, + it will avoid any ports that seem to be in use by other devices. + + * IRQ autoprobing works only for a few port types at the moment. + +Reporting printer problems with parport +======================================= + +If you are having problems printing, please go through these steps to +try to narrow down where the problem area is. + +When reporting problems with parport, really you need to give all of +the messages that ``parport_pc`` spits out when it initialises. There are +several code paths: + +- polling +- interrupt-driven, protocol in software +- interrupt-driven, protocol in hardware using PIO +- interrupt-driven, protocol in hardware using DMA + +The kernel messages that ``parport_pc`` logs give an indication of which +code path is being used. (They could be a lot better actually..) + +For normal printer protocol, having IEEE 1284 modes enabled or not +should not make a difference. + +To turn off the 'protocol in hardware' code paths, disable +``CONFIG_PARPORT_PC_FIFO``. Note that when they are enabled they are not +necessarily **used**; it depends on whether the hardware is available, +enabled by the BIOS, and detected by the driver. + +So, to start with, disable ``CONFIG_PARPORT_PC_FIFO``, and load ``parport_pc`` +with ``irq=none``. See if printing works then. It really should, +because this is the simplest code path. + +If that works fine, try with ``io=0x378 irq=7`` (adjust for your +hardware), to make it use interrupt-driven in-software protocol. + +If **that** works fine, then one of the hardware modes isn't working +right. Enable ``CONFIG_FIFO`` (no, it isn't a module option, +and yes, it should be), set the port to ECP mode in the BIOS and note +the DMA channel, and try with:: + + io=0x378 irq=7 dma=none (for PIO) + io=0x378 irq=7 dma=3 (for DMA) + +---------- + +philb@gnu.org +tim@cyberelk.net diff --git a/Documentation/admin-guide/ramoops.rst b/Documentation/admin-guide/ramoops.rst new file mode 100644 index 000000000000..4efd7ce77565 --- /dev/null +++ b/Documentation/admin-guide/ramoops.rst @@ -0,0 +1,156 @@ +Ramoops oops/panic logger +========================= + +Sergiu Iordache <sergiu@chromium.org> + +Updated: 17 November 2011 + +Introduction +------------ + +Ramoops is an oops/panic logger that writes its logs to RAM before the system +crashes. It works by logging oopses and panics in a circular buffer. Ramoops +needs a system with persistent RAM so that the content of that area can +survive after a restart. + +Ramoops concepts +---------------- + +Ramoops uses a predefined memory area to store the dump. The start and size +and type of the memory area are set using three variables: + + * ``mem_address`` for the start + * ``mem_size`` for the size. The memory size will be rounded down to a + power of two. + * ``mem_type`` to specifiy if the memory type (default is pgprot_writecombine). + +Typically the default value of ``mem_type=0`` should be used as that sets the pstore +mapping to pgprot_writecombine. Setting ``mem_type=1`` attempts to use +``pgprot_noncached``, which only works on some platforms. This is because pstore +depends on atomic operations. At least on ARM, pgprot_noncached causes the +memory to be mapped strongly ordered, and atomic operations on strongly ordered +memory are implementation defined, and won't work on many ARMs such as omaps. + +The memory area is divided into ``record_size`` chunks (also rounded down to +power of two) and each oops/panic writes a ``record_size`` chunk of +information. + +Dumping both oopses and panics can be done by setting 1 in the ``dump_oops`` +variable while setting 0 in that variable dumps only the panics. + +The module uses a counter to record multiple dumps but the counter gets reset +on restart (i.e. new dumps after the restart will overwrite old ones). + +Ramoops also supports software ECC protection of persistent memory regions. +This might be useful when a hardware reset was used to bring the machine back +to life (i.e. a watchdog triggered). In such cases, RAM may be somewhat +corrupt, but usually it is restorable. + +Setting the parameters +---------------------- + +Setting the ramoops parameters can be done in several different manners: + + A. Use the module parameters (which have the names of the variables described + as before). For quick debugging, you can also reserve parts of memory during + boot and then use the reserved memory for ramoops. For example, assuming a + machine with > 128 MB of memory, the following kernel command line will tell + the kernel to use only the first 128 MB of memory, and place ECC-protected + ramoops region at 128 MB boundary:: + + mem=128M ramoops.mem_address=0x8000000 ramoops.ecc=1 + + B. Use Device Tree bindings, as described in + ``Documentation/device-tree/bindings/reserved-memory/admin-guide/ramoops.rst``. + For example:: + + reserved-memory { + #address-cells = <2>; + #size-cells = <2>; + ranges; + + ramoops@8f000000 { + compatible = "ramoops"; + reg = <0 0x8f000000 0 0x100000>; + record-size = <0x4000>; + console-size = <0x4000>; + }; + }; + + C. Use a platform device and set the platform data. The parameters can then + be set through that platform data. An example of doing that is: + + .. code-block:: c + + #include <linux/pstore_ram.h> + [...] + + static struct ramoops_platform_data ramoops_data = { + .mem_size = <...>, + .mem_address = <...>, + .mem_type = <...>, + .record_size = <...>, + .dump_oops = <...>, + .ecc = <...>, + }; + + static struct platform_device ramoops_dev = { + .name = "ramoops", + .dev = { + .platform_data = &ramoops_data, + }, + }; + + [... inside a function ...] + int ret; + + ret = platform_device_register(&ramoops_dev); + if (ret) { + printk(KERN_ERR "unable to register platform device\n"); + return ret; + } + +You can specify either RAM memory or peripheral devices' memory. However, when +specifying RAM, be sure to reserve the memory by issuing memblock_reserve() +very early in the architecture code, e.g.:: + + #include <linux/memblock.h> + + memblock_reserve(ramoops_data.mem_address, ramoops_data.mem_size); + +Dump format +----------- + +The data dump begins with a header, currently defined as ``====`` followed by a +timestamp and a new line. The dump then continues with the actual data. + +Reading the data +---------------- + +The dump data can be read from the pstore filesystem. The format for these +files is ``dmesg-ramoops-N``, where N is the record number in memory. To delete +a stored record from RAM, simply unlink the respective pstore file. + +Persistent function tracing +--------------------------- + +Persistent function tracing might be useful for debugging software or hardware +related hangs. The functions call chain log is stored in a ``ftrace-ramoops`` +file. Here is an example of usage:: + + # mount -t debugfs debugfs /sys/kernel/debug/ + # echo 1 > /sys/kernel/debug/pstore/record_ftrace + # reboot -f + [...] + # mount -t pstore pstore /mnt/ + # tail /mnt/ftrace-ramoops + 0 ffffffff8101ea64 ffffffff8101bcda native_apic_mem_read <- disconnect_bsp_APIC+0x6a/0xc0 + 0 ffffffff8101ea44 ffffffff8101bcf6 native_apic_mem_write <- disconnect_bsp_APIC+0x86/0xc0 + 0 ffffffff81020084 ffffffff8101a4b5 hpet_disable <- native_machine_shutdown+0x75/0x90 + 0 ffffffff81005f94 ffffffff8101a4bb iommu_shutdown_noop <- native_machine_shutdown+0x7b/0x90 + 0 ffffffff8101a6a1 ffffffff8101a437 native_machine_emergency_restart <- native_machine_restart+0x37/0x40 + 0 ffffffff811f9876 ffffffff8101a73a acpi_reboot <- native_machine_emergency_restart+0xaa/0x1e0 + 0 ffffffff8101a514 ffffffff8101a772 mach_reboot_fixups <- native_machine_emergency_restart+0xe2/0x1e0 + 0 ffffffff811d9c54 ffffffff8101a7a0 __const_udelay <- native_machine_emergency_restart+0x110/0x1e0 + 0 ffffffff811d9c34 ffffffff811d9c80 __delay <- __const_udelay+0x30/0x40 + 0 ffffffff811d9d14 ffffffff811d9c3f delay_tsc <- __delay+0xf/0x20 diff --git a/Documentation/admin-guide/ras.rst b/Documentation/admin-guide/ras.rst new file mode 100644 index 000000000000..d71340e86c27 --- /dev/null +++ b/Documentation/admin-guide/ras.rst @@ -0,0 +1,1190 @@ +.. include:: <isonum.txt> + +============================================ +Reliability, Availability and Serviceability +============================================ + +RAS concepts +************ + +Reliability, Availability and Serviceability (RAS) is a concept used on +servers meant to measure their robusteness. + +Reliability + is the probability that a system will produce correct outputs. + + * Generally measured as Mean Time Between Failures (MTBF) + * Enhanced by features that help to avoid, detect and repair hardware faults + +Availability + is the probability that a system is operational at a given time + + * Generally measured as a percentage of downtime per a period of time + * Often uses mechanisms to detect and correct hardware faults in + runtime; + +Serviceability (or maintainability) + is the simplicity and speed with which a system can be repaired or + maintained + + * Generally measured on Mean Time Between Repair (MTBR) + +Improving RAS +------------- + +In order to reduce systems downtime, a system should be capable of detecting +hardware errors, and, when possible correcting them in runtime. It should +also provide mechanisms to detect hardware degradation, in order to warn +the system administrator to take the action of replacing a component before +it causes data loss or system downtime. + +Among the monitoring measures, the most usual ones include: + +* CPU – detect errors at instruction execution and at L1/L2/L3 caches; +* Memory – add error correction logic (ECC) to detect and correct errors; +* I/O – add CRC checksums for tranfered data; +* Storage – RAID, journal file systems, checksums, + Self-Monitoring, Analysis and Reporting Technology (SMART). + +By monitoring the number of occurrences of error detections, it is possible +to identify if the probability of hardware errors is increasing, and, on such +case, do a preventive maintainance to replace a degrated component while +those errors are correctable. + +Types of errors +--------------- + +Most mechanisms used on modern systems use use technologies like Hamming +Codes that allow error correction when the number of errors on a bit packet +is below a threshold. If the number of errors is above, those mechanisms +can indicate with a high degree of confidence that an error happened, but +they can't correct. + +Also, sometimes an error occur on a component that it is not used. For +example, a part of the memory that it is not currently allocated. + +That defines some categories of errors: + +* **Correctable Error (CE)** - the error detection mechanism detected and + corrected the error. Such errors are usually not fatal, although some + Kernel mechanisms allow the system administrator to consider them as fatal. + +* **Uncorrected Error (UE)** - the amount of errors happened above the error + correction threshold, and the system was unable to auto-correct. + +* **Fatal Error** - when an UE error happens on a critical component of the + system (for example, a piece of the Kernel got corrupted by an UE), the + only reliable way to avoid data corruption is to hang or reboot the machine. + +* **Non-fatal Error** - when an UE error happens on an unused component, + like a CPU in power down state or an unused memory bank, the system may + still run, eventually replacing the affected hardware by a hot spare, + if available. + + Also, when an error happens on an userspace process, it is also possible to + kill such process and let userspace restart it. + +The mechanism for handling non-fatal errors is usually complex and may +require the help of some userspace application, in order to apply the +policy desired by the system administrator. + +Identifying a bad hardware component +------------------------------------ + +Just detecting a hardware flaw is usually not enough, as the system needs +to pinpoint to the minimal replaceable unit (MRU) that should be exchanged +to make the hardware reliable again. + +So, it requires not only error logging facilities, but also mechanisms that +will translate the error message to the silkscreen or component label for +the MRU. + +Typically, it is very complex for memory, as modern CPUs interlace memory +from different memory modules, in order to provide a better performance. The +DMI BIOS usually have a list of memory module labels, with can be obtained +using the ``dmidecode`` tool. For example, on a desktop machine, it shows:: + + Memory Device + Total Width: 64 bits + Data Width: 64 bits + Size: 16384 MB + Form Factor: SODIMM + Set: None + Locator: ChannelA-DIMM0 + Bank Locator: BANK 0 + Type: DDR4 + Type Detail: Synchronous + Speed: 2133 MHz + Rank: 2 + Configured Clock Speed: 2133 MHz + +On the above example, a DDR4 SO-DIMM memory module is located at the +system's memory labeled as "BANK 0", as given by the *bank locator* field. +Please notice that, on such system, the *total width* is equal to the +*data witdh*. It means that such memory module doesn't have error +detection/correction mechanisms. + +Unfortunately, not all systems use the same field to specify the memory +bank. On this example, from an older server, ``dmidecode`` shows:: + + Memory Device + Array Handle: 0x1000 + Error Information Handle: Not Provided + Total Width: 72 bits + Data Width: 64 bits + Size: 8192 MB + Form Factor: DIMM + Set: 1 + Locator: DIMM_A1 + Bank Locator: Not Specified + Type: DDR3 + Type Detail: Synchronous Registered (Buffered) + Speed: 1600 MHz + Rank: 2 + Configured Clock Speed: 1600 MHz + +There, the DDR3 RDIMM memory module is located at the system's memory labeled +as "DIMM_A1", as given by the *locator* field. Please notice that this +memory module has 64 bits of *data witdh* and 72 bits of *total width*. So, +it has 8 extra bits to be used by error detection and correction mechanisms. +Such kind of memory is called Error-correcting code memory (ECC memory). + +To make things even worse, it is not uncommon that systems with different +labels on their system's board to use exactly the same BIOS, meaning that +the labels provided by the BIOS won't match the real ones. + +ECC memory +---------- + +As mentioned on the previous section, ECC memory has extra bits to be +used for error correction. So, on 64 bit systems, a memory module +has 64 bits of *data width*, and 74 bits of *total width*. So, there are +8 bits extra bits to be used for the error detection and correction +mechanisms. Those extra bits are called *syndrome*\ [#f1]_\ [#f2]_. + +So, when the cpu requests the memory controller to write a word with +*data width*, the memory controller calculates the *syndrome* in real time, +using Hamming code, or some other error correction code, like SECDED+, +producing a code with *total width* size. Such code is then written +on the memory modules. + +At read, the *total width* bits code is converted back, using the same +ECC code used on write, producing a word with *data width* and a *syndrome*. +The word with *data width* is sent to the CPU, even when errors happen. + +The memory controller also looks at the *syndrome* in order to check if +there was an error, and if the ECC code was able to fix such error. +If the error was corrected, a Corrected Error (CE) happened. If not, an +Uncorrected Error (UE) happened. + +The information about the CE/UE errors is stored on some special registers +at the memory controller and can be accessed by reading such registers, +either by BIOS, by some special CPUs or by Linux EDAC driver. On x86 64 +bit CPUs, such errors can also be retrieved via the Machine Check +Architecture (MCA)\ [#f3]_. + +.. [#f1] Please notice that several memory controllers allow operation on a + mode called "Lock-Step", where it groups two memory modules together, + doing 128-bit reads/writes. That gives 16 bits for error correction, with + significatively improves the error correction mechanism, at the expense + that, when an error happens, there's no way to know what memory module is + to blame. So, it has to blame both memory modules. + +.. [#f2] Some memory controllers also allow using memory in mirror mode. + On such mode, the same data is written to two memory modules. At read, + the system checks both memory modules, in order to check if both provide + identical data. On such configuration, when an error happens, there's no + way to know what memory module is to blame. So, it has to blame both + memory modules (or 4 memory modules, if the system is also on Lock-step + mode). + +.. [#f3] For more details about the Machine Check Architecture (MCA), + please read Documentation/x86/x86_64/machinecheck at the Kernel tree. + +EDAC - Error Detection And Correction +************************************* + +.. note:: + + "bluesmoke" was the name for this device driver subsystem when it + was "out-of-tree" and maintained at http://bluesmoke.sourceforge.net. + That site is mostly archaic now and can be used only for historical + purposes. + + When the subsystem was pushed upstream for the first time, on + Kernel 2.6.16, for the first time, it was renamed to ``EDAC``. + +Purpose +------- + +The ``edac`` kernel module's goal is to detect and report hardware errors +that occur within the computer system running under linux. + +Memory +------ + +Memory Correctable Errors (CE) and Uncorrectable Errors (UE) are the +primary errors being harvested. These types of errors are harvested by +the ``edac_mc`` device. + +Detecting CE events, then harvesting those events and reporting them, +**can** but must not necessarily be a predictor of future UE events. With +CE events only, the system can and will continue to operate as no data +has been damaged yet. + +However, preventive maintenance and proactive part replacement of memory +modules exhibiting CEs can reduce the likelihood of the dreaded UE events +and system panics. + +Other hardware elements +----------------------- + +A new feature for EDAC, the ``edac_device`` class of device, was added in +the 2.6.23 version of the kernel. + +This new device type allows for non-memory type of ECC hardware detectors +to have their states harvested and presented to userspace via the sysfs +interface. + +Some architectures have ECC detectors for L1, L2 and L3 caches, +along with DMA engines, fabric switches, main data path switches, +interconnections, and various other hardware data paths. If the hardware +reports it, then a edac_device device probably can be constructed to +harvest and present that to userspace. + + +PCI bus scanning +---------------- + +In addition, PCI devices are scanned for PCI Bus Parity and SERR Errors +in order to determine if errors are occurring during data transfers. + +The presence of PCI Parity errors must be examined with a grain of salt. +There are several add-in adapters that do **not** follow the PCI specification +with regards to Parity generation and reporting. The specification says +the vendor should tie the parity status bits to 0 if they do not intend +to generate parity. Some vendors do not do this, and thus the parity bit +can "float" giving false positives. + +There is a PCI device attribute located in sysfs that is checked by +the EDAC PCI scanning code. If that attribute is set, PCI parity/error +scanning is skipped for that device. The attribute is:: + + broken_parity_status + +and is located in ``/sys/devices/pci<XXX>/0000:XX:YY.Z`` directories for +PCI devices. + + +Versioning +---------- + +EDAC is composed of a "core" module (``edac_core.ko``) and several Memory +Controller (MC) driver modules. On a given system, the CORE is loaded +and one MC driver will be loaded. Both the CORE and the MC driver (or +``edac_device`` driver) have individual versions that reflect current +release level of their respective modules. + +Thus, to "report" on what version a system is running, one must report +both the CORE's and the MC driver's versions. + + +Loading +------- + +If ``edac`` was statically linked with the kernel then no loading +is necessary. If ``edac`` was built as modules then simply modprobe +the ``edac`` pieces that you need. You should be able to modprobe +hardware-specific modules and have the dependencies load the necessary +core modules. + +Example:: + + $ modprobe amd76x_edac + +loads both the ``amd76x_edac.ko`` memory controller module and the +``edac_mc.ko`` core module. + + +Sysfs interface +--------------- + +EDAC presents a ``sysfs`` interface for control and reporting purposes. It +lives in the /sys/devices/system/edac directory. + +Within this directory there currently reside 2 components: + + ======= ============================== + mc memory controller(s) system + pci PCI control and status system + ======= ============================== + + + +Memory Controller (mc) Model +---------------------------- + +Each ``mc`` device controls a set of memory modules [#f4]_. These modules +are laid out in a Chip-Select Row (``csrowX``) and Channel table (``chX``). +There can be multiple csrows and multiple channels. + +.. [#f4] Nowadays, the term DIMM (Dual In-line Memory Module) is widely + used to refer to a memory module, although there are other memory + packaging alternatives, like SO-DIMM, SIMM, etc. Along this document, + and inside the EDAC system, the term "dimm" is used for all memory + modules, even when they use a different kind of packaging. + +Memory controllers allow for several csrows, with 8 csrows being a +typical value. Yet, the actual number of csrows depends on the layout of +a given motherboard, memory controller and memory module characteristics. + +Dual channels allow for dual data length (e. g. 128 bits, on 64 bit systems) +data transfers to/from the CPU from/to memory. Some newer chipsets allow +for more than 2 channels, like Fully Buffered DIMMs (FB-DIMMs) memory +controllers. The following example will assume 2 channels: + + +------------+-----------------------+ + | Chip | Channels | + | Select +-----------+-----------+ + | rows | ``ch0`` | ``ch1`` | + +============+===========+===========+ + | ``csrow0`` | DIMM_A0 | DIMM_B0 | + +------------+ | | + | ``csrow1`` | | | + +------------+-----------+-----------+ + | ``csrow2`` | DIMM_A1 | DIMM_B1 | + +------------+ | | + | ``csrow3`` | | | + +------------+-----------+-----------+ + +In the above example, there are 4 physical slots on the motherboard +for memory DIMMs: + + +---------+---------+ + | DIMM_A0 | DIMM_B0 | + +---------+---------+ + | DIMM_A1 | DIMM_B1 | + +---------+---------+ + +Labels for these slots are usually silk-screened on the motherboard. +Slots labeled ``A`` are channel 0 in this example. Slots labeled ``B`` are +channel 1. Notice that there are two csrows possible on a physical DIMM. +These csrows are allocated their csrow assignment based on the slot into +which the memory DIMM is placed. Thus, when 1 DIMM is placed in each +Channel, the csrows cross both DIMMs. + +Memory DIMMs come single or dual "ranked". A rank is a populated csrow. +Thus, 2 single ranked DIMMs, placed in slots DIMM_A0 and DIMM_B0 above +will have just one csrow (csrow0). csrow1 will be empty. On the other +hand, when 2 dual ranked DIMMs are similarly placed, then both csrow0 +and csrow1 will be populated. The pattern repeats itself for csrow2 and +csrow3. + +The representation of the above is reflected in the directory +tree in EDAC's sysfs interface. Starting in directory +``/sys/devices/system/edac/mc``, each memory controller will be +represented by its own ``mcX`` directory, where ``X`` is the +index of the MC:: + + ..../edac/mc/ + | + |->mc0 + |->mc1 + |->mc2 + .... + +Under each ``mcX`` directory each ``csrowX`` is again represented by a +``csrowX``, where ``X`` is the csrow index:: + + .../mc/mc0/ + | + |->csrow0 + |->csrow2 + |->csrow3 + .... + +Notice that there is no csrow1, which indicates that csrow0 is composed +of a single ranked DIMMs. This should also apply in both Channels, in +order to have dual-channel mode be operational. Since both csrow2 and +csrow3 are populated, this indicates a dual ranked set of DIMMs for +channels 0 and 1. + +Within each of the ``mcX`` and ``csrowX`` directories are several EDAC +control and attribute files. + +``mcX`` directories +------------------- + +In ``mcX`` directories are EDAC control and attribute files for +this ``X`` instance of the memory controllers. + +For a description of the sysfs API, please see: + + Documentation/ABI/testing/sysfs-devices-edac + + +``dimmX`` or ``rankX`` directories +---------------------------------- + +The recommended way to use the EDAC subsystem is to look at the information +provided by the ``dimmX`` or ``rankX`` directories [#f5]_. + +A typical EDAC system has the following structure under +``/sys/devices/system/edac/``\ [#f6]_:: + + /sys/devices/system/edac/ + ├── mc + │ ├── mc0 + │ │ ├── ce_count + │ │ ├── ce_noinfo_count + │ │ ├── dimm0 + │ │ │ ├── dimm_dev_type + │ │ │ ├── dimm_edac_mode + │ │ │ ├── dimm_label + │ │ │ ├── dimm_location + │ │ │ ├── dimm_mem_type + │ │ │ ├── size + │ │ │ └── uevent + │ │ ├── max_location + │ │ ├── mc_name + │ │ ├── reset_counters + │ │ ├── seconds_since_reset + │ │ ├── size_mb + │ │ ├── ue_count + │ │ ├── ue_noinfo_count + │ │ └── uevent + │ ├── mc1 + │ │ ├── ce_count + │ │ ├── ce_noinfo_count + │ │ ├── dimm0 + │ │ │ ├── dimm_dev_type + │ │ │ ├── dimm_edac_mode + │ │ │ ├── dimm_label + │ │ │ ├── dimm_location + │ │ │ ├── dimm_mem_type + │ │ │ ├── size + │ │ │ └── uevent + │ │ ├── max_location + │ │ ├── mc_name + │ │ ├── reset_counters + │ │ ├── seconds_since_reset + │ │ ├── size_mb + │ │ ├── ue_count + │ │ ├── ue_noinfo_count + │ │ └── uevent + │ └── uevent + └── uevent + +In the ``dimmX`` directories are EDAC control and attribute files for +this ``X`` memory module: + +- ``size`` - Total memory managed by this csrow attribute file + + This attribute file displays, in count of megabytes, the memory + that this csrow contains. + +- ``dimm_dev_type`` - Device type attribute file + + This attribute file will display what type of DRAM device is + being utilized on this DIMM. + Examples: + + - x1 + - x2 + - x4 + - x8 + +- ``dimm_edac_mode`` - EDAC Mode of operation attribute file + + This attribute file will display what type of Error detection + and correction is being utilized. + +- ``dimm_label`` - memory module label control file + + This control file allows this DIMM to have a label assigned + to it. With this label in the module, when errors occur + the output can provide the DIMM label in the system log. + This becomes vital for panic events to isolate the + cause of the UE event. + + DIMM Labels must be assigned after booting, with information + that correctly identifies the physical slot with its + silk screen label. This information is currently very + motherboard specific and determination of this information + must occur in userland at this time. + +- ``dimm_location`` - location of the memory module + + The location can have up to 3 levels, and describe how the + memory controller identifies the location of a memory module. + Depending on the type of memory and memory controller, it + can be: + + - *csrow* and *channel* - used when the memory controller + doesn't identify a single DIMM - e. g. in ``rankX`` dir; + - *branch*, *channel*, *slot* - typically used on FB-DIMM memory + controllers; + - *channel*, *slot* - used on Nehalem and newer Intel drivers. + +- ``dimm_mem_type`` - Memory Type attribute file + + This attribute file will display what type of memory is currently + on this csrow. Normally, either buffered or unbuffered memory. + Examples: + + - Registered-DDR + - Unbuffered-DDR + +.. [#f5] On some systems, the memory controller doesn't have any logic + to identify the memory module. On such systems, the directory is called ``rankX`` and works on a similar way as the ``csrowX`` directories. + On modern Intel memory controllers, the memory controller identifies the + memory modules directly. On such systems, the directory is called ``dimmX``. + +.. [#f6] There are also some ``power`` directories and ``subsystem`` + symlinks inside the sysfs mapping that are automatically created by + the sysfs subsystem. Currently, they serve no purpose. + +``csrowX`` directories +---------------------- + +When CONFIG_EDAC_LEGACY_SYSFS is enabled, sysfs will contain the ``csrowX`` +directories. As this API doesn't work properly for Rambus, FB-DIMMs and +modern Intel Memory Controllers, this is being deprecated in favor of +``dimmX`` directories. + +In the ``csrowX`` directories are EDAC control and attribute files for +this ``X`` instance of csrow: + + +- ``ue_count`` - Total Uncorrectable Errors count attribute file + + This attribute file displays the total count of uncorrectable + errors that have occurred on this csrow. If panic_on_ue is set + this counter will not have a chance to increment, since EDAC + will panic the system. + + +- ``ce_count`` - Total Correctable Errors count attribute file + + This attribute file displays the total count of correctable + errors that have occurred on this csrow. This count is very + important to examine. CEs provide early indications that a + DIMM is beginning to fail. This count field should be + monitored for non-zero values and report such information + to the system administrator. + + +- ``size_mb`` - Total memory managed by this csrow attribute file + + This attribute file displays, in count of megabytes, the memory + that this csrow contains. + + +- ``mem_type`` - Memory Type attribute file + + This attribute file will display what type of memory is currently + on this csrow. Normally, either buffered or unbuffered memory. + Examples: + + - Registered-DDR + - Unbuffered-DDR + + +- ``edac_mode`` - EDAC Mode of operation attribute file + + This attribute file will display what type of Error detection + and correction is being utilized. + + +- ``dev_type`` - Device type attribute file + + This attribute file will display what type of DRAM device is + being utilized on this DIMM. + Examples: + + - x1 + - x2 + - x4 + - x8 + + +- ``ch0_ce_count`` - Channel 0 CE Count attribute file + + This attribute file will display the count of CEs on this + DIMM located in channel 0. + + +- ``ch0_ue_count`` - Channel 0 UE Count attribute file + + This attribute file will display the count of UEs on this + DIMM located in channel 0. + + +- ``ch0_dimm_label`` - Channel 0 DIMM Label control file + + + This control file allows this DIMM to have a label assigned + to it. With this label in the module, when errors occur + the output can provide the DIMM label in the system log. + This becomes vital for panic events to isolate the + cause of the UE event. + + DIMM Labels must be assigned after booting, with information + that correctly identifies the physical slot with its + silk screen label. This information is currently very + motherboard specific and determination of this information + must occur in userland at this time. + + +- ``ch1_ce_count`` - Channel 1 CE Count attribute file + + + This attribute file will display the count of CEs on this + DIMM located in channel 1. + + +- ``ch1_ue_count`` - Channel 1 UE Count attribute file + + + This attribute file will display the count of UEs on this + DIMM located in channel 0. + + +- ``ch1_dimm_label`` - Channel 1 DIMM Label control file + + This control file allows this DIMM to have a label assigned + to it. With this label in the module, when errors occur + the output can provide the DIMM label in the system log. + This becomes vital for panic events to isolate the + cause of the UE event. + + DIMM Labels must be assigned after booting, with information + that correctly identifies the physical slot with its + silk screen label. This information is currently very + motherboard specific and determination of this information + must occur in userland at this time. + + +System Logging +-------------- + +If logging for UEs and CEs is enabled, then system logs will contain +information indicating that errors have been detected:: + + EDAC MC0: CE page 0x283, offset 0xce0, grain 8, syndrome 0x6ec3, row 0, channel 1 "DIMM_B1": amd76x_edac + EDAC MC0: CE page 0x1e5, offset 0xfb0, grain 8, syndrome 0xb741, row 0, channel 1 "DIMM_B1": amd76x_edac + + +The structure of the message is: + + +---------------------------------------+-------------+ + | Content + Example | + +=======================================+=============+ + | The memory controller | MC0 | + +---------------------------------------+-------------+ + | Error type | CE | + +---------------------------------------+-------------+ + | Memory page | 0x283 | + +---------------------------------------+-------------+ + | Offset in the page | 0xce0 | + +---------------------------------------+-------------+ + | The byte granularity | grain 8 | + | or resolution of the error | | + +---------------------------------------+-------------+ + | The error syndrome | 0xb741 | + +---------------------------------------+-------------+ + | Memory row | row 0 + + +---------------------------------------+-------------+ + | Memory channel | channel 1 | + +---------------------------------------+-------------+ + | DIMM label, if set prior | DIMM B1 | + +---------------------------------------+-------------+ + | And then an optional, driver-specific | | + | message that may have additional | | + | information. | | + +---------------------------------------+-------------+ + +Both UEs and CEs with no info will lack all but memory controller, error +type, a notice of "no info" and then an optional, driver-specific error +message. + + +PCI Bus Parity Detection +------------------------ + +On Header Type 00 devices, the primary status is looked at for any +parity error regardless of whether parity is enabled on the device or +not. (The spec indicates parity is generated in some cases). On Header +Type 01 bridges, the secondary status register is also looked at to see +if parity occurred on the bus on the other side of the bridge. + + +Sysfs configuration +------------------- + +Under ``/sys/devices/system/edac/pci`` are control and attribute files as +follows: + + +- ``check_pci_parity`` - Enable/Disable PCI Parity checking control file + + This control file enables or disables the PCI Bus Parity scanning + operation. Writing a 1 to this file enables the scanning. Writing + a 0 to this file disables the scanning. + + Enable:: + + echo "1" >/sys/devices/system/edac/pci/check_pci_parity + + Disable:: + + echo "0" >/sys/devices/system/edac/pci/check_pci_parity + + +- ``pci_parity_count`` - Parity Count + + This attribute file will display the number of parity errors that + have been detected. + + +Module parameters +----------------- + +- ``edac_mc_panic_on_ue`` - Panic on UE control file + + An uncorrectable error will cause a machine panic. This is usually + desirable. It is a bad idea to continue when an uncorrectable error + occurs - it is indeterminate what was uncorrected and the operating + system context might be so mangled that continuing will lead to further + corruption. If the kernel has MCE configured, then EDAC will never + notice the UE. + + LOAD TIME:: + + module/kernel parameter: edac_mc_panic_on_ue=[0|1] + + RUN TIME:: + + echo "1" > /sys/module/edac_core/parameters/edac_mc_panic_on_ue + + +- ``edac_mc_log_ue`` - Log UE control file + + + Generate kernel messages describing uncorrectable errors. These errors + are reported through the system message log system. UE statistics + will be accumulated even when UE logging is disabled. + + LOAD TIME:: + + module/kernel parameter: edac_mc_log_ue=[0|1] + + RUN TIME:: + + echo "1" > /sys/module/edac_core/parameters/edac_mc_log_ue + + +- ``edac_mc_log_ce`` - Log CE control file + + + Generate kernel messages describing correctable errors. These + errors are reported through the system message log system. + CE statistics will be accumulated even when CE logging is disabled. + + LOAD TIME:: + + module/kernel parameter: edac_mc_log_ce=[0|1] + + RUN TIME:: + + echo "1" > /sys/module/edac_core/parameters/edac_mc_log_ce + + +- ``edac_mc_poll_msec`` - Polling period control file + + + The time period, in milliseconds, for polling for error information. + Too small a value wastes resources. Too large a value might delay + necessary handling of errors and might loose valuable information for + locating the error. 1000 milliseconds (once each second) is the current + default. Systems which require all the bandwidth they can get, may + increase this. + + LOAD TIME:: + + module/kernel parameter: edac_mc_poll_msec=[0|1] + + RUN TIME:: + + echo "1000" > /sys/module/edac_core/parameters/edac_mc_poll_msec + + +- ``panic_on_pci_parity`` - Panic on PCI PARITY Error + + + This control file enables or disables panicking when a parity + error has been detected. + + + module/kernel parameter:: + + edac_panic_on_pci_pe=[0|1] + + Enable:: + + echo "1" > /sys/module/edac_core/parameters/edac_panic_on_pci_pe + + Disable:: + + echo "0" > /sys/module/edac_core/parameters/edac_panic_on_pci_pe + + + +EDAC device type +---------------- + +In the header file, edac_pci.h, there is a series of edac_device structures +and APIs for the EDAC_DEVICE. + +User space access to an edac_device is through the sysfs interface. + +At the location ``/sys/devices/system/edac`` (sysfs) new edac_device devices +will appear. + +There is a three level tree beneath the above ``edac`` directory. For example, +the ``test_device_edac`` device (found at the http://bluesmoke.sourceforget.net +website) installs itself as:: + + /sys/devices/system/edac/test-instance + +in this directory are various controls, a symlink and one or more ``instance`` +directories. + +The standard default controls are: + + ============== ======================================================= + log_ce boolean to log CE events + log_ue boolean to log UE events + panic_on_ue boolean to ``panic`` the system if an UE is encountered + (default off, can be set true via startup script) + poll_msec time period between POLL cycles for events + ============== ======================================================= + +The test_device_edac device adds at least one of its own custom control: + + ============== ================================================== + test_bits which in the current test driver does nothing but + show how it is installed. A ported driver can + add one or more such controls and/or attributes + for specific uses. + One out-of-tree driver uses controls here to allow + for ERROR INJECTION operations to hardware + injection registers + ============== ================================================== + +The symlink points to the 'struct dev' that is registered for this edac_device. + +Instances +--------- + +One or more instance directories are present. For the ``test_device_edac`` +case: + + +----------------+ + | test-instance0 | + +----------------+ + + +In this directory there are two default counter attributes, which are totals of +counter in deeper subdirectories. + + ============== ==================================== + ce_count total of CE events of subdirectories + ue_count total of UE events of subdirectories + ============== ==================================== + +Blocks +------ + +At the lowest directory level is the ``block`` directory. There can be 0, 1 +or more blocks specified in each instance: + + +-------------+ + | test-block0 | + +-------------+ + +In this directory the default attributes are: + + ============== ================================================ + ce_count which is counter of CE events for this ``block`` + of hardware being monitored + ue_count which is counter of UE events for this ``block`` + of hardware being monitored + ============== ================================================ + + +The ``test_device_edac`` device adds 4 attributes and 1 control: + + ================== ==================================================== + test-block-bits-0 for every POLL cycle this counter + is incremented + test-block-bits-1 every 10 cycles, this counter is bumped once, + and test-block-bits-0 is set to 0 + test-block-bits-2 every 100 cycles, this counter is bumped once, + and test-block-bits-1 is set to 0 + test-block-bits-3 every 1000 cycles, this counter is bumped once, + and test-block-bits-2 is set to 0 + ================== ==================================================== + + + ================== ==================================================== + reset-counters writing ANY thing to this control will + reset all the above counters. + ================== ==================================================== + + +Use of the ``test_device_edac`` driver should enable any others to create their own +unique drivers for their hardware systems. + +The ``test_device_edac`` sample driver is located at the +http://bluesmoke.sourceforge.net project site for EDAC. + + +Usage of EDAC APIs on Nehalem and newer Intel CPUs +-------------------------------------------------- + +On older Intel architectures, the memory controller was part of the North +Bridge chipset. Nehalem, Sandy Bridge, Ivy Bridge, Haswell, Sky Lake and +newer Intel architectures integrated an enhanced version of the memory +controller (MC) inside the CPUs. + +This chapter will cover the differences of the enhanced memory controllers +found on newer Intel CPUs, such as ``i7core_edac``, ``sb_edac`` and +``sbx_edac`` drivers. + +.. note:: + + The Xeon E7 processor families use a separate chip for the memory + controller, called Intel Scalable Memory Buffer. This section doesn't + apply for such families. + +1) There is one Memory Controller per Quick Patch Interconnect + (QPI). At the driver, the term "socket" means one QPI. This is + associated with a physical CPU socket. + + Each MC have 3 physical read channels, 3 physical write channels and + 3 logic channels. The driver currently sees it as just 3 channels. + Each channel can have up to 3 DIMMs. + + The minimum known unity is DIMMs. There are no information about csrows. + As EDAC API maps the minimum unity is csrows, the driver sequentially + maps channel/DIMM into different csrows. + + For example, supposing the following layout:: + + Ch0 phy rd0, wr0 (0x063f4031): 2 ranks, UDIMMs + dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400 + dimm 1 1024 Mb offset: 4, bank: 8, rank: 1, row: 0x4000, col: 0x400 + Ch1 phy rd1, wr1 (0x063f4031): 2 ranks, UDIMMs + dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400 + Ch2 phy rd3, wr3 (0x063f4031): 2 ranks, UDIMMs + dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400 + + The driver will map it as:: + + csrow0: channel 0, dimm0 + csrow1: channel 0, dimm1 + csrow2: channel 1, dimm0 + csrow3: channel 2, dimm0 + + exports one DIMM per csrow. + + Each QPI is exported as a different memory controller. + +2) The MC has the ability to inject errors to test drivers. The drivers + implement this functionality via some error injection nodes: + + For injecting a memory error, there are some sysfs nodes, under + ``/sys/devices/system/edac/mc/mc?/``: + + - ``inject_addrmatch/*``: + Controls the error injection mask register. It is possible to specify + several characteristics of the address to match an error code:: + + dimm = the affected dimm. Numbers are relative to a channel; + rank = the memory rank; + channel = the channel that will generate an error; + bank = the affected bank; + page = the page address; + column (or col) = the address column. + + each of the above values can be set to "any" to match any valid value. + + At driver init, all values are set to any. + + For example, to generate an error at rank 1 of dimm 2, for any channel, + any bank, any page, any column:: + + echo 2 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/dimm + echo 1 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/rank + + To return to the default behaviour of matching any, you can do:: + + echo any >/sys/devices/system/edac/mc/mc0/inject_addrmatch/dimm + echo any >/sys/devices/system/edac/mc/mc0/inject_addrmatch/rank + + - ``inject_eccmask``: + specifies what bits will have troubles, + + - ``inject_section``: + specifies what ECC cache section will get the error:: + + 3 for both + 2 for the highest + 1 for the lowest + + - ``inject_type``: + specifies the type of error, being a combination of the following bits:: + + bit 0 - repeat + bit 1 - ecc + bit 2 - parity + + - ``inject_enable``: + starts the error generation when something different than 0 is written. + + All inject vars can be read. root permission is needed for write. + + Datasheet states that the error will only be generated after a write on an + address that matches inject_addrmatch. It seems, however, that reading will + also produce an error. + + For example, the following code will generate an error for any write access + at socket 0, on any DIMM/address on channel 2:: + + echo 2 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/channel + echo 2 >/sys/devices/system/edac/mc/mc0/inject_type + echo 64 >/sys/devices/system/edac/mc/mc0/inject_eccmask + echo 3 >/sys/devices/system/edac/mc/mc0/inject_section + echo 1 >/sys/devices/system/edac/mc/mc0/inject_enable + dd if=/dev/mem of=/dev/null seek=16k bs=4k count=1 >& /dev/null + + For socket 1, it is needed to replace "mc0" by "mc1" at the above + commands. + + The generated error message will look like:: + + EDAC MC0: UE row 0, channel-a= 0 channel-b= 0 labels "-": NON_FATAL (addr = 0x0075b980, socket=0, Dimm=0, Channel=2, syndrome=0x00000040, count=1, Err=8c0000400001009f:4000080482 (read error: read ECC error)) + +3) Corrected Error memory register counters + + Those newer MCs have some registers to count memory errors. The driver + uses those registers to report Corrected Errors on devices with Registered + DIMMs. + + However, those counters don't work with Unregistered DIMM. As the chipset + offers some counters that also work with UDIMMs (but with a worse level of + granularity than the default ones), the driver exposes those registers for + UDIMM memories. + + They can be read by looking at the contents of ``all_channel_counts/``:: + + $ for i in /sys/devices/system/edac/mc/mc0/all_channel_counts/*; do echo $i; cat $i; done + /sys/devices/system/edac/mc/mc0/all_channel_counts/udimm0 + 0 + /sys/devices/system/edac/mc/mc0/all_channel_counts/udimm1 + 0 + /sys/devices/system/edac/mc/mc0/all_channel_counts/udimm2 + 0 + + What happens here is that errors on different csrows, but at the same + dimm number will increment the same counter. + So, in this memory mapping:: + + csrow0: channel 0, dimm0 + csrow1: channel 0, dimm1 + csrow2: channel 1, dimm0 + csrow3: channel 2, dimm0 + + The hardware will increment udimm0 for an error at the first dimm at either + csrow0, csrow2 or csrow3; + + The hardware will increment udimm1 for an error at the second dimm at either + csrow0, csrow2 or csrow3; + + The hardware will increment udimm2 for an error at the third dimm at either + csrow0, csrow2 or csrow3; + +4) Standard error counters + + The standard error counters are generated when an mcelog error is received + by the driver. Since, with UDIMM, this is counted by software, it is + possible that some errors could be lost. With RDIMM's, they display the + contents of the registers + +Reference documents used on ``amd64_edac`` +------------------------------------------ + +``amd64_edac`` module is based on the following documents +(available from http://support.amd.com/en-us/search/tech-docs): + +1. :Title: BIOS and Kernel Developer's Guide for AMD Athlon 64 and AMD + Opteron Processors + :AMD publication #: 26094 + :Revision: 3.26 + :Link: http://support.amd.com/TechDocs/26094.PDF + +2. :Title: BIOS and Kernel Developer's Guide for AMD NPT Family 0Fh + Processors + :AMD publication #: 32559 + :Revision: 3.00 + :Issue Date: May 2006 + :Link: http://support.amd.com/TechDocs/32559.pdf + +3. :Title: BIOS and Kernel Developer's Guide (BKDG) For AMD Family 10h + Processors + :AMD publication #: 31116 + :Revision: 3.00 + :Issue Date: September 07, 2007 + :Link: http://support.amd.com/TechDocs/31116.pdf + +4. :Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 15h + Models 30h-3Fh Processors + :AMD publication #: 49125 + :Revision: 3.06 + :Issue Date: 2/12/2015 (latest release) + :Link: http://support.amd.com/TechDocs/49125_15h_Models_30h-3Fh_BKDG.pdf + +5. :Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 15h + Models 60h-6Fh Processors + :AMD publication #: 50742 + :Revision: 3.01 + :Issue Date: 7/23/2015 (latest release) + :Link: http://support.amd.com/TechDocs/50742_15h_Models_60h-6Fh_BKDG.pdf + +6. :Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 16h + Models 00h-0Fh Processors + :AMD publication #: 48751 + :Revision: 3.03 + :Issue Date: 2/23/2015 (latest release) + :Link: http://support.amd.com/TechDocs/48751_16h_bkdg.pdf + +Credits +======= + +* Written by Doug Thompson <dougthompson@xmission.com> + + - 7 Dec 2005 + - 17 Jul 2007 Updated + +* |copy| Mauro Carvalho Chehab + + - 05 Aug 2009 Nehalem interface + - 26 Oct 2016 Converted to ReST and cleanups at the Nehalem section + +* EDAC authors/maintainers: + + - Doug Thompson, Dave Jiang, Dave Peterson et al, + - Mauro Carvalho Chehab + - Borislav Petkov + - original author: Thayne Harbaugh diff --git a/Documentation/admin-guide/reporting-bugs.rst b/Documentation/admin-guide/reporting-bugs.rst new file mode 100644 index 000000000000..26b60b419652 --- /dev/null +++ b/Documentation/admin-guide/reporting-bugs.rst @@ -0,0 +1,182 @@ +.. _reportingbugs: + +Reporting bugs +++++++++++++++ + +Background +========== + +The upstream Linux kernel maintainers only fix bugs for specific kernel +versions. Those versions include the current "release candidate" (or -rc) +kernel, any "stable" kernel versions, and any "long term" kernels. + +Please see https://www.kernel.org/ for a list of supported kernels. Any +kernel marked with [EOL] is "end of life" and will not have any fixes +backported to it. + +If you've found a bug on a kernel version that isn't listed on kernel.org, +contact your Linux distribution or embedded vendor for support. +Alternatively, you can attempt to run one of the supported stable or -rc +kernels, and see if you can reproduce the bug on that. It's preferable +to reproduce the bug on the latest -rc kernel. + + +How to report Linux kernel bugs +=============================== + + +Identify the problematic subsystem +---------------------------------- + +Identifying which part of the Linux kernel might be causing your issue +increases your chances of getting your bug fixed. Simply posting to the +generic linux-kernel mailing list (LKML) may cause your bug report to be +lost in the noise of a mailing list that gets 1000+ emails a day. + +Instead, try to figure out which kernel subsystem is causing the issue, +and email that subsystem's maintainer and mailing list. If the subsystem +maintainer doesn't answer, then expand your scope to mailing lists like +LKML. + + +Identify who to notify +---------------------- + +Once you know the subsystem that is causing the issue, you should send a +bug report. Some maintainers prefer bugs to be reported via bugzilla +(https://bugzilla.kernel.org), while others prefer that bugs be reported +via the subsystem mailing list. + +To find out where to send an emailed bug report, find your subsystem or +device driver in the MAINTAINERS file. Search in the file for relevant +entries, and send your bug report to the person(s) listed in the "M:" +lines, making sure to Cc the mailing list(s) in the "L:" lines. When the +maintainer replies to you, make sure to 'Reply-all' in order to keep the +public mailing list(s) in the email thread. + +If you know which driver is causing issues, you can pass one of the driver +files to the get_maintainer.pl script:: + + perl scripts/get_maintainer.pl -f <filename> + +If it is a security bug, please copy the Security Contact listed in the +MAINTAINERS file. They can help coordinate bugfix and disclosure. See +:ref:`Documentation/admin-guide/security-bugs.rst <securitybugs>` for more information. + +If you can't figure out which subsystem caused the issue, you should file +a bug in kernel.org bugzilla and send email to +linux-kernel@vger.kernel.org, referencing the bugzilla URL. (For more +information on the linux-kernel mailing list see +http://www.tux.org/lkml/). + + +Tips for reporting bugs +----------------------- + +If you haven't reported a bug before, please read: + + http://www.chiark.greenend.org.uk/~sgtatham/bugs.html + + http://www.catb.org/esr/faqs/smart-questions.html + +It's REALLY important to report bugs that seem unrelated as separate email +threads or separate bugzilla entries. If you report several unrelated +bugs at once, it's difficult for maintainers to tease apart the relevant +data. + + +Gather information +------------------ + +The most important information in a bug report is how to reproduce the +bug. This includes system information, and (most importantly) +step-by-step instructions for how a user can trigger the bug. + +If the failure includes an "OOPS:", take a picture of the screen, capture +a netconsole trace, or type the message from your screen into the bug +report. Please read "Documentation/admin-guide/oops-tracing.rst" before posting your +bug report. This explains what you should do with the "Oops" information +to make it useful to the recipient. + +This is a suggested format for a bug report sent via email or bugzilla. +Having a standardized bug report form makes it easier for you not to +overlook things, and easier for the developers to find the pieces of +information they're really interested in. If some information is not +relevant to your bug, feel free to exclude it. + +First run the ver_linux script included as scripts/ver_linux, which +reports the version of some important subsystems. Run this script with +the command ``awk -f scripts/ver_linux``. + +Use that information to fill in all fields of the bug report form, and +post it to the mailing list with a subject of "PROBLEM: <one line +summary from [1.]>" for easy identification by the developers:: + + [1.] One line summary of the problem: + [2.] Full description of the problem/report: + [3.] Keywords (i.e., modules, networking, kernel): + [4.] Kernel information + [4.1.] Kernel version (from /proc/version): + [4.2.] Kernel .config file: + [5.] Most recent kernel version which did not have the bug: + [6.] Output of Oops.. message (if applicable) with symbolic information + resolved (see Documentation/admin-guide/oops-tracing.rst) + [7.] A small shell script or example program which triggers the + problem (if possible) + [8.] Environment + [8.1.] Software (add the output of the ver_linux script here) + [8.2.] Processor information (from /proc/cpuinfo): + [8.3.] Module information (from /proc/modules): + [8.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem) + [8.5.] PCI information ('lspci -vvv' as root) + [8.6.] SCSI information (from /proc/scsi/scsi) + [8.7.] Other information that might be relevant to the problem + (please look in /proc and include all information that you + think to be relevant): + [X.] Other notes, patches, fixes, workarounds: + + +Follow up +========= + +Expectations for bug reporters +------------------------------ + +Linux kernel maintainers expect bug reporters to be able to follow up on +bug reports. That may include running new tests, applying patches, +recompiling your kernel, and/or re-triggering your bug. The most +frustrating thing for maintainers is for someone to report a bug, and then +never follow up on a request to try out a fix. + +That said, it's still useful for a kernel maintainer to know a bug exists +on a supported kernel, even if you can't follow up with retests. Follow +up reports, such as replying to the email thread with "I tried the latest +kernel and I can't reproduce my bug anymore" are also helpful, because +maintainers have to assume silence means things are still broken. + +Expectations for kernel maintainers +----------------------------------- + +Linux kernel maintainers are busy, overworked human beings. Some times +they may not be able to address your bug in a day, a week, or two weeks. +If they don't answer your email, they may be on vacation, or at a Linux +conference. Check the conference schedule at https://LWN.net for more info: + + https://lwn.net/Calendar/ + +In general, kernel maintainers take 1 to 5 business days to respond to +bugs. The majority of kernel maintainers are employed to work on the +kernel, and they may not work on the weekends. Maintainers are scattered +around the world, and they may not work in your time zone. Unless you +have a high priority bug, please wait at least a week after the first bug +report before sending the maintainer a reminder email. + +The exceptions to this rule are regressions, kernel crashes, security holes, +or userspace breakage caused by new kernel behavior. Those bugs should be +addressed by the maintainers ASAP. If you suspect a maintainer is not +responding to these types of bugs in a timely manner (especially during a +merge window), escalate the bug to LKML and Linus Torvalds. + +Thank you! + +[Some of this is taken from Frohwalt Egerer's original linux-kernel FAQ] diff --git a/Documentation/admin-guide/security-bugs.rst b/Documentation/admin-guide/security-bugs.rst new file mode 100644 index 000000000000..4f7414cad586 --- /dev/null +++ b/Documentation/admin-guide/security-bugs.rst @@ -0,0 +1,46 @@ +.. _securitybugs: + +Security bugs +============= + +Linux kernel developers take security very seriously. As such, we'd +like to know when a security bug is found so that it can be fixed and +disclosed as quickly as possible. Please report security bugs to the +Linux kernel security team. + +Contact +------- + +The Linux kernel security team can be contacted by email at +<security@kernel.org>. This is a private list of security officers +who will help verify the bug report and develop and release a fix. +It is possible that the security team will bring in extra help from +area maintainers to understand and fix the security vulnerability. + +As it is with any bug, the more information provided the easier it +will be to diagnose and fix. Please review the procedure outlined in +admin-guide/reporting-bugs.rst if you are unclear about what information is helpful. +Any exploit code is very helpful and will not be released without +consent from the reporter unless it has already been made public. + +Disclosure +---------- + +The goal of the Linux kernel security team is to work with the +bug submitter to bug resolution as well as disclosure. We prefer +to fully disclose the bug as soon as possible. It is reasonable to +delay disclosure when the bug or the fix is not yet fully understood, +the solution is not well-tested or for vendor coordination. However, we +expect these delays to be short, measurable in days, not weeks or months. +A disclosure date is negotiated by the security team working with the +bug submitter as well as vendors. However, the kernel security team +holds the final say when setting a disclosure date. The timeframe for +disclosure is from immediate (esp. if it's already publicly known) +to a few weeks. As a basic default policy, we expect report date to +disclosure date to be on the order of 7 days. + +Non-disclosure agreements +------------------------- + +The Linux kernel security team is not a formal body and therefore unable +to enter any non-disclosure agreements. diff --git a/Documentation/admin-guide/serial-console.rst b/Documentation/admin-guide/serial-console.rst new file mode 100644 index 000000000000..a8d1e36b627a --- /dev/null +++ b/Documentation/admin-guide/serial-console.rst @@ -0,0 +1,115 @@ +.. _serial_console: + +Linux Serial Console +==================== + +To use a serial port as console you need to compile the support into your +kernel - by default it is not compiled in. For PC style serial ports +it's the config option next to menu option: + +:menuselection:`Character devices --> Serial drivers --> 8250/16550 and compatible serial support --> Console on 8250/16550 and compatible serial port` + +You must compile serial support into the kernel and not as a module. + +It is possible to specify multiple devices for console output. You can +define a new kernel command line option to select which device(s) to +use for console output. + +The format of this option is:: + + console=device,options + + device: tty0 for the foreground virtual console + ttyX for any other virtual console + ttySx for a serial port + lp0 for the first parallel port + ttyUSB0 for the first USB serial device + + options: depend on the driver. For the serial port this + defines the baudrate/parity/bits/flow control of + the port, in the format BBBBPNF, where BBBB is the + speed, P is parity (n/o/e), N is number of bits, + and F is flow control ('r' for RTS). Default is + 9600n8. The maximum baudrate is 115200. + +You can specify multiple console= options on the kernel command line. +Output will appear on all of them. The last device will be used when +you open ``/dev/console``. So, for example:: + + console=ttyS1,9600 console=tty0 + +defines that opening ``/dev/console`` will get you the current foreground +virtual console, and kernel messages will appear on both the VGA +console and the 2nd serial port (ttyS1 or COM2) at 9600 baud. + +Note that you can only define one console per device type (serial, video). + +If no console device is specified, the first device found capable of +acting as a system console will be used. At this time, the system +first looks for a VGA card and then for a serial port. So if you don't +have a VGA card in your system the first serial port will automatically +become the console. + +You will need to create a new device to use ``/dev/console``. The official +``/dev/console`` is now character device 5,1. + +(You can also use a network device as a console. See +``Documentation/networking/netconsole.txt`` for information on that.) + +Here's an example that will use ``/dev/ttyS1`` (COM2) as the console. +Replace the sample values as needed. + +1. Create ``/dev/console`` (real console) and ``/dev/tty0`` (master virtual + console):: + + cd /dev + rm -f console tty0 + mknod -m 622 console c 5 1 + mknod -m 622 tty0 c 4 0 + +2. LILO can also take input from a serial device. This is a very + useful option. To tell LILO to use the serial port: + In lilo.conf (global section):: + + serial = 1,9600n8 (ttyS1, 9600 bd, no parity, 8 bits) + +3. Adjust to kernel flags for the new kernel, + again in lilo.conf (kernel section):: + + append = "console=ttyS1,9600" + +4. Make sure a getty runs on the serial port so that you can login to + it once the system is done booting. This is done by adding a line + like this to ``/etc/inittab`` (exact syntax depends on your getty):: + + S1:23:respawn:/sbin/getty -L ttyS1 9600 vt100 + +5. Init and ``/etc/ioctl.save`` + + Sysvinit remembers its stty settings in a file in ``/etc``, called + ``/etc/ioctl.save``. REMOVE THIS FILE before using the serial + console for the first time, because otherwise init will probably + set the baudrate to 38400 (baudrate of the virtual console). + +6. ``/dev/console`` and X + Programs that want to do something with the virtual console usually + open ``/dev/console``. If you have created the new ``/dev/console`` device, + and your console is NOT the virtual console some programs will fail. + Those are programs that want to access the VT interface, and use + ``/dev/console instead of /dev/tty0``. Some of those programs are:: + + Xfree86, svgalib, gpm, SVGATextMode + + It should be fixed in modern versions of these programs though. + + Note that if you boot without a ``console=`` option (or with + ``console=/dev/tty0``), ``/dev/console`` is the same as ``/dev/tty0``. + In that case everything will still work. + +7. Thanks + + Thanks to Geert Uytterhoeven <geert@linux-m68k.org> + for porting the patches from 2.1.4x to 2.1.6x for taking care of + the integration of these patches into m68k, ppc and alpha. + +Miquel van Smoorenburg <miquels@cistron.nl>, 11-Jun-2000 diff --git a/Documentation/admin-guide/sysfs-rules.rst b/Documentation/admin-guide/sysfs-rules.rst new file mode 100644 index 000000000000..abad33526aca --- /dev/null +++ b/Documentation/admin-guide/sysfs-rules.rst @@ -0,0 +1,192 @@ +Rules on how to access information in sysfs +=========================================== + +The kernel-exported sysfs exports internal kernel implementation details +and depends on internal kernel structures and layout. It is agreed upon +by the kernel developers that the Linux kernel does not provide a stable +internal API. Therefore, there are aspects of the sysfs interface that +may not be stable across kernel releases. + +To minimize the risk of breaking users of sysfs, which are in most cases +low-level userspace applications, with a new kernel release, the users +of sysfs must follow some rules to use an as-abstract-as-possible way to +access this filesystem. The current udev and HAL programs already +implement this and users are encouraged to plug, if possible, into the +abstractions these programs provide instead of accessing sysfs directly. + +But if you really do want or need to access sysfs directly, please follow +the following rules and then your programs should work with future +versions of the sysfs interface. + +- Do not use libsysfs + It makes assumptions about sysfs which are not true. Its API does not + offer any abstraction, it exposes all the kernel driver-core + implementation details in its own API. Therefore it is not better than + reading directories and opening the files yourself. + Also, it is not actively maintained, in the sense of reflecting the + current kernel development. The goal of providing a stable interface + to sysfs has failed; it causes more problems than it solves. It + violates many of the rules in this document. + +- sysfs is always at ``/sys`` + Parsing ``/proc/mounts`` is a waste of time. Other mount points are a + system configuration bug you should not try to solve. For test cases, + possibly support a ``SYSFS_PATH`` environment variable to overwrite the + application's behavior, but never try to search for sysfs. Never try + to mount it, if you are not an early boot script. + +- devices are only "devices" + There is no such thing like class-, bus-, physical devices, + interfaces, and such that you can rely on in userspace. Everything is + just simply a "device". Class-, bus-, physical, ... types are just + kernel implementation details which should not be expected by + applications that look for devices in sysfs. + + The properties of a device are: + + - devpath (``/devices/pci0000:00/0000:00:1d.1/usb2/2-2/2-2:1.0``) + + - identical to the DEVPATH value in the event sent from the kernel + at device creation and removal + - the unique key to the device at that point in time + - the kernel's path to the device directory without the leading + ``/sys``, and always starting with a slash + - all elements of a devpath must be real directories. Symlinks + pointing to /sys/devices must always be resolved to their real + target and the target path must be used to access the device. + That way the devpath to the device matches the devpath of the + kernel used at event time. + - using or exposing symlink values as elements in a devpath string + is a bug in the application + + - kernel name (``sda``, ``tty``, ``0000:00:1f.2``, ...) + + - a directory name, identical to the last element of the devpath + - applications need to handle spaces and characters like ``!`` in + the name + + - subsystem (``block``, ``tty``, ``pci``, ...) + + - simple string, never a path or a link + - retrieved by reading the "subsystem"-link and using only the + last element of the target path + + - driver (``tg3``, ``ata_piix``, ``uhci_hcd``) + + - a simple string, which may contain spaces, never a path or a + link + - it is retrieved by reading the "driver"-link and using only the + last element of the target path + - devices which do not have "driver"-link just do not have a + driver; copying the driver value in a child device context is a + bug in the application + + - attributes + + - the files in the device directory or files below subdirectories + of the same device directory + - accessing attributes reached by a symlink pointing to another device, + like the "device"-link, is a bug in the application + + Everything else is just a kernel driver-core implementation detail + that should not be assumed to be stable across kernel releases. + +- Properties of parent devices never belong into a child device. + Always look at the parent devices themselves for determining device + context properties. If the device ``eth0`` or ``sda`` does not have a + "driver"-link, then this device does not have a driver. Its value is empty. + Never copy any property of the parent-device into a child-device. Parent + device properties may change dynamically without any notice to the + child device. + +- Hierarchy in a single device tree + There is only one valid place in sysfs where hierarchy can be examined + and this is below: ``/sys/devices.`` + It is planned that all device directories will end up in the tree + below this directory. + +- Classification by subsystem + There are currently three places for classification of devices: + ``/sys/block,`` ``/sys/class`` and ``/sys/bus.`` It is planned that these will + not contain any device directories themselves, but only flat lists of + symlinks pointing to the unified ``/sys/devices`` tree. + All three places have completely different rules on how to access + device information. It is planned to merge all three + classification directories into one place at ``/sys/subsystem``, + following the layout of the bus directories. All buses and + classes, including the converted block subsystem, will show up + there. + The devices belonging to a subsystem will create a symlink in the + "devices" directory at ``/sys/subsystem/<name>/devices``, + + If ``/sys/subsystem`` exists, ``/sys/bus``, ``/sys/class`` and ``/sys/block`` + can be ignored. If it does not exist, you always have to scan all three + places, as the kernel is free to move a subsystem from one place to + the other, as long as the devices are still reachable by the same + subsystem name. + + Assuming ``/sys/class/<subsystem>`` and ``/sys/bus/<subsystem>``, or + ``/sys/block`` and ``/sys/class/block`` are not interchangeable is a bug in + the application. + +- Block + The converted block subsystem at ``/sys/class/block`` or + ``/sys/subsystem/block`` will contain the links for disks and partitions + at the same level, never in a hierarchy. Assuming the block subsystem to + contain only disks and not partition devices in the same flat list is + a bug in the application. + +- "device"-link and <subsystem>:<kernel name>-links + Never depend on the "device"-link. The "device"-link is a workaround + for the old layout, where class devices are not created in + ``/sys/devices/`` like the bus devices. If the link-resolving of a + device directory does not end in ``/sys/devices/``, you can use the + "device"-link to find the parent devices in ``/sys/devices/``, That is the + single valid use of the "device"-link; it must never appear in any + path as an element. Assuming the existence of the "device"-link for + a device in ``/sys/devices/`` is a bug in the application. + Accessing ``/sys/class/net/eth0/device`` is a bug in the application. + + Never depend on the class-specific links back to the ``/sys/class`` + directory. These links are also a workaround for the design mistake + that class devices are not created in ``/sys/devices.`` If a device + directory does not contain directories for child devices, these links + may be used to find the child devices in ``/sys/class.`` That is the single + valid use of these links; they must never appear in any path as an + element. Assuming the existence of these links for devices which are + real child device directories in the ``/sys/devices`` tree is a bug in + the application. + + It is planned to remove all these links when all class device + directories live in ``/sys/devices.`` + +- Position of devices along device chain can change. + Never depend on a specific parent device position in the devpath, + or the chain of parent devices. The kernel is free to insert devices into + the chain. You must always request the parent device you are looking for + by its subsystem value. You need to walk up the chain until you find + the device that matches the expected subsystem. Depending on a specific + position of a parent device or exposing relative paths using ``../`` to + access the chain of parents is a bug in the application. + +- When reading and writing sysfs device attribute files, avoid dependency + on specific error codes wherever possible. This minimizes coupling to + the error handling implementation within the kernel. + + In general, failures to read or write sysfs device attributes shall + propagate errors wherever possible. Common errors include, but are not + limited to: + + ``-EIO``: The read or store operation is not supported, typically + returned by the sysfs system itself if the read or store pointer + is ``NULL``. + + ``-ENXIO``: The read or store operation failed + + Error codes will not be changed without good reason, and should a change + to error codes result in user-space breakage, it will be fixed, or the + the offending change will be reverted. + + Userspace applications can, however, expect the format and contents of + the attribute files to remain consistent in the absence of a version + attribute change in the context of a given attribute. diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst new file mode 100644 index 000000000000..d1712ea2d314 --- /dev/null +++ b/Documentation/admin-guide/sysrq.rst @@ -0,0 +1,289 @@ +Linux Magic System Request Key Hacks +==================================== + +Documentation for sysrq.c + +What is the magic SysRq key? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +It is a 'magical' key combo you can hit which the kernel will respond to +regardless of whatever else it is doing, unless it is completely locked up. + +How do I enable the magic SysRq key? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +You need to say "yes" to 'Magic SysRq key (CONFIG_MAGIC_SYSRQ)' when +configuring the kernel. When running a kernel with SysRq compiled in, +/proc/sys/kernel/sysrq controls the functions allowed to be invoked via +the SysRq key. The default value in this file is set by the +CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE config symbol, which itself defaults +to 1. Here is the list of possible values in /proc/sys/kernel/sysrq: + + - 0 - disable sysrq completely + - 1 - enable all functions of sysrq + - >1 - bitmask of allowed sysrq functions (see below for detailed function + description):: + + 2 = 0x2 - enable control of console logging level + 4 = 0x4 - enable control of keyboard (SAK, unraw) + 8 = 0x8 - enable debugging dumps of processes etc. + 16 = 0x10 - enable sync command + 32 = 0x20 - enable remount read-only + 64 = 0x40 - enable signalling of processes (term, kill, oom-kill) + 128 = 0x80 - allow reboot/poweroff + 256 = 0x100 - allow nicing of all RT tasks + +You can set the value in the file by the following command:: + + echo "number" >/proc/sys/kernel/sysrq + +The number may be written here either as decimal or as hexadecimal +with the 0x prefix. CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE must always be +written in hexadecimal. + +Note that the value of ``/proc/sys/kernel/sysrq`` influences only the invocation +via a keyboard. Invocation of any operation via ``/proc/sysrq-trigger`` is +always allowed (by a user with admin privileges). + +How do I use the magic SysRq key? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +On x86 - You press the key combo :kbd:`ALT-SysRq-<command key>`. + +.. note:: + Some + keyboards may not have a key labeled 'SysRq'. The 'SysRq' key is + also known as the 'Print Screen' key. Also some keyboards cannot + handle so many keys being pressed at the same time, so you might + have better luck with press :kbd:`Alt`, press :kbd:`SysRq`, + release :kbd:`SysRq`, press :kbd:`<command key>`, release everything. + +On SPARC - You press :kbd:`ALT-STOP-<command key>`, I believe. + +On the serial console (PC style standard serial ports only) + You send a ``BREAK``, then within 5 seconds a command key. Sending + ``BREAK`` twice is interpreted as a normal BREAK. + +On PowerPC + Press :kbd:`ALT - Print Screen` (or :kbd:`F13`) - :kbd:`<command key>`, + :kbd:`Print Screen` (or :kbd:`F13`) - :kbd:`<command key>` may suffice. + +On other + If you know of the key combos for other architectures, please + let me know so I can add them to this section. + +On all + write a character to /proc/sysrq-trigger. e.g.:: + + echo t > /proc/sysrq-trigger + +What are the 'command' keys? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +=========== =================================================================== +Command Function +=========== =================================================================== +``b`` Will immediately reboot the system without syncing or unmounting + your disks. + +``c`` Will perform a system crash by a NULL pointer dereference. + A crashdump will be taken if configured. + +``d`` Shows all locks that are held. + +``e`` Send a SIGTERM to all processes, except for init. + +``f`` Will call the oom killer to kill a memory hog process, but do not + panic if nothing can be killed. + +``g`` Used by kgdb (kernel debugger) + +``h`` Will display help (actually any other key than those listed + here will display help. but ``h`` is easy to remember :-) + +``i`` Send a SIGKILL to all processes, except for init. + +``j`` Forcibly "Just thaw it" - filesystems frozen by the FIFREEZE ioctl. + +``k`` Secure Access Key (SAK) Kills all programs on the current virtual + console. NOTE: See important comments below in SAK section. + +``l`` Shows a stack backtrace for all active CPUs. + +``m`` Will dump current memory info to your console. + +``n`` Used to make RT tasks nice-able + +``o`` Will shut your system off (if configured and supported). + +``p`` Will dump the current registers and flags to your console. + +``q`` Will dump per CPU lists of all armed hrtimers (but NOT regular + timer_list timers) and detailed information about all + clockevent devices. + +``r`` Turns off keyboard raw mode and sets it to XLATE. + +``s`` Will attempt to sync all mounted filesystems. + +``t`` Will dump a list of current tasks and their information to your + console. + +``u`` Will attempt to remount all mounted filesystems read-only. + +``v`` Forcefully restores framebuffer console +``v`` Causes ETM buffer dump [ARM-specific] + +``w`` Dumps tasks that are in uninterruptable (blocked) state. + +``x`` Used by xmon interface on ppc/powerpc platforms. + Show global PMU Registers on sparc64. + Dump all TLB entries on MIPS. + +``y`` Show global CPU Registers [SPARC-64 specific] + +``z`` Dump the ftrace buffer + +``0``-``9`` Sets the console log level, controlling which kernel messages + will be printed to your console. (``0``, for example would make + it so that only emergency messages like PANICs or OOPSes would + make it to your console.) +=========== =================================================================== + +Okay, so what can I use them for? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Well, unraw(r) is very handy when your X server or a svgalib program crashes. + +sak(k) (Secure Access Key) is useful when you want to be sure there is no +trojan program running at console which could grab your password +when you would try to login. It will kill all programs on given console, +thus letting you make sure that the login prompt you see is actually +the one from init, not some trojan program. + +.. important:: + + In its true form it is not a true SAK like the one in a + c2 compliant system, and it should not be mistaken as + such. + +It seems others find it useful as (System Attention Key) which is +useful when you want to exit a program that will not let you switch consoles. +(For example, X or a svgalib program.) + +``reboot(b)`` is good when you're unable to shut down. But you should also +``sync(s)`` and ``umount(u)`` first. + +``crash(c)`` can be used to manually trigger a crashdump when the system is hung. +Note that this just triggers a crash if there is no dump mechanism available. + +``sync(s)`` is great when your system is locked up, it allows you to sync your +disks and will certainly lessen the chance of data loss and fscking. Note +that the sync hasn't taken place until you see the "OK" and "Done" appear +on the screen. (If the kernel is really in strife, you may not ever get the +OK or Done message...) + +``umount(u)`` is basically useful in the same ways as ``sync(s)``. I generally +``sync(s)``, ``umount(u)``, then ``reboot(b)`` when my system locks. It's saved +me many a fsck. Again, the unmount (remount read-only) hasn't taken place until +you see the "OK" and "Done" message appear on the screen. + +The loglevels ``0``-``9`` are useful when your console is being flooded with +kernel messages you do not want to see. Selecting ``0`` will prevent all but +the most urgent kernel messages from reaching your console. (They will +still be logged if syslogd/klogd are alive, though.) + +``term(e)`` and ``kill(i)`` are useful if you have some sort of runaway process +you are unable to kill any other way, especially if it's spawning other +processes. + +"just thaw ``it(j)``" is useful if your system becomes unresponsive due to a +frozen (probably root) filesystem via the FIFREEZE ioctl. + +Sometimes SysRq seems to get 'stuck' after using it, what can I do? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +That happens to me, also. I've found that tapping shift, alt, and control +on both sides of the keyboard, and hitting an invalid sysrq sequence again +will fix the problem. (i.e., something like :kbd:`alt-sysrq-z`). Switching to +another virtual console (:kbd:`ALT+Fn`) and then back again should also help. + +I hit SysRq, but nothing seems to happen, what's wrong? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +There are some keyboards that produce a different keycode for SysRq than the +pre-defined value of 99 (see ``KEY_SYSRQ`` in ``include/linux/input.h``), or +which don't have a SysRq key at all. In these cases, run ``showkey -s`` to find +an appropriate scancode sequence, and use ``setkeycodes <sequence> 99`` to map +this sequence to the usual SysRq code (e.g., ``setkeycodes e05b 99``). It's +probably best to put this command in a boot script. Oh, and by the way, you +exit ``showkey`` by not typing anything for ten seconds. + +I want to add SysRQ key events to a module, how does it work? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +In order to register a basic function with the table, you must first include +the header ``include/linux/sysrq.h``, this will define everything else you need. +Next, you must create a ``sysrq_key_op`` struct, and populate it with A) the key +handler function you will use, B) a help_msg string, that will print when SysRQ +prints help, and C) an action_msg string, that will print right before your +handler is called. Your handler must conform to the prototype in 'sysrq.h'. + +After the ``sysrq_key_op`` is created, you can call the kernel function +``register_sysrq_key(int key, struct sysrq_key_op *op_p);`` this will +register the operation pointed to by ``op_p`` at table key 'key', +if that slot in the table is blank. At module unload time, you must call +the function ``unregister_sysrq_key(int key, struct sysrq_key_op *op_p)``, which +will remove the key op pointed to by 'op_p' from the key 'key', if and only if +it is currently registered in that slot. This is in case the slot has been +overwritten since you registered it. + +The Magic SysRQ system works by registering key operations against a key op +lookup table, which is defined in 'drivers/tty/sysrq.c'. This key table has +a number of operations registered into it at compile time, but is mutable, +and 2 functions are exported for interface to it:: + + register_sysrq_key and unregister_sysrq_key. + +Of course, never ever leave an invalid pointer in the table. I.e., when +your module that called register_sysrq_key() exits, it must call +unregister_sysrq_key() to clean up the sysrq key table entry that it used. +Null pointers in the table are always safe. :) + +If for some reason you feel the need to call the handle_sysrq function from +within a function called by handle_sysrq, you must be aware that you are in +a lock (you are also in an interrupt handler, which means don't sleep!), so +you must call ``__handle_sysrq_nolock`` instead. + +When I hit a SysRq key combination only the header appears on the console? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Sysrq output is subject to the same console loglevel control as all +other console output. This means that if the kernel was booted 'quiet' +as is common on distro kernels the output may not appear on the actual +console, even though it will appear in the dmesg buffer, and be accessible +via the dmesg command and to the consumers of ``/proc/kmsg``. As a specific +exception the header line from the sysrq command is passed to all console +consumers as if the current loglevel was maximum. If only the header +is emitted it is almost certain that the kernel loglevel is too low. +Should you require the output on the console channel then you will need +to temporarily up the console loglevel using :kbd:`alt-sysrq-8` or:: + + echo 8 > /proc/sysrq-trigger + +Remember to return the loglevel to normal after triggering the sysrq +command you are interested in. + +I have more questions, who can I ask? +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Just ask them on the linux-kernel mailing list: + linux-kernel@vger.kernel.org + +Credits +~~~~~~~ + +Written by Mydraal <vulpyne@vulpyne.net> +Updated by Adam Sulmicki <adam@cfar.umd.edu> +Updated by Jeremy M. Dolan <jmd@turbogeek.org> 2001/01/28 10:15:59 +Added to by Crutcher Dunnavant <crutcher+kernel@datastacks.com> diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst new file mode 100644 index 000000000000..1df03b5cb02f --- /dev/null +++ b/Documentation/admin-guide/tainted-kernels.rst @@ -0,0 +1,59 @@ +Tainted kernels +--------------- + +Some oops reports contain the string **'Tainted: '** after the program +counter. This indicates that the kernel has been tainted by some +mechanism. The string is followed by a series of position-sensitive +characters, each representing a particular tainted value. + + 1) 'G' if all modules loaded have a GPL or compatible license, 'P' if + any proprietary module has been loaded. Modules without a + MODULE_LICENSE or with a MODULE_LICENSE that is not recognised by + insmod as GPL compatible are assumed to be proprietary. + + 2) ``F`` if any module was force loaded by ``insmod -f``, ``' '`` if all + modules were loaded normally. + + 3) ``S`` if the oops occurred on an SMP kernel running on hardware that + hasn't been certified as safe to run multiprocessor. + Currently this occurs only on various Athlons that are not + SMP capable. + + 4) ``R`` if a module was force unloaded by ``rmmod -f``, ``' '`` if all + modules were unloaded normally. + + 5) ``M`` if any processor has reported a Machine Check Exception, + ``' '`` if no Machine Check Exceptions have occurred. + + 6) ``B`` if a page-release function has found a bad page reference or + some unexpected page flags. + + 7) ``U`` if a user or user application specifically requested that the + Tainted flag be set, ``' '`` otherwise. + + 8) ``D`` if the kernel has died recently, i.e. there was an OOPS or BUG. + + 9) ``A`` if the ACPI table has been overridden. + + 10) ``W`` if a warning has previously been issued by the kernel. + (Though some warnings may set more specific taint flags.) + + 11) ``C`` if a staging driver has been loaded. + + 12) ``I`` if the kernel is working around a severe bug in the platform + firmware (BIOS or similar). + + 13) ``O`` if an externally-built ("out-of-tree") module has been loaded. + + 14) ``E`` if an unsigned module has been loaded in a kernel supporting + module signature. + + 15) ``L`` if a soft lockup has previously occurred on the system. + + 16) ``K`` if the kernel has been live patched. + +The primary reason for the **'Tainted: '** string is to tell kernel +debuggers if this is a clean kernel or if anything unusual has +occurred. Tainting is permanent: even if an offending module is +unloaded, the tainted value remains to indicate that the kernel is not +trustworthy. diff --git a/Documentation/admin-guide/unicode.rst b/Documentation/admin-guide/unicode.rst new file mode 100644 index 000000000000..7425a3351321 --- /dev/null +++ b/Documentation/admin-guide/unicode.rst @@ -0,0 +1,189 @@ +Unicode support +=============== + + Last update: 2005-01-17, version 1.4 + +This file is maintained by H. Peter Anvin <unicode@lanana.org> as part +of the Linux Assigned Names And Numbers Authority (LANANA) project. +The current version can be found at: + + http://www.lanana.org/docs/unicode/admin-guide/unicode.rst + +Introduction +------------ + +The Linux kernel code has been rewritten to use Unicode to map +characters to fonts. By downloading a single Unicode-to-font table, +both the eight-bit character sets and UTF-8 mode are changed to use +the font as indicated. + +This changes the semantics of the eight-bit character tables subtly. +The four character tables are now: + +=============== =============================== ================ +Map symbol Map name Escape code (G0) +=============== =============================== ================ +LAT1_MAP Latin-1 (ISO 8859-1) ESC ( B +GRAF_MAP DEC VT100 pseudographics ESC ( 0 +IBMPC_MAP IBM code page 437 ESC ( U +USER_MAP User defined ESC ( K +=============== =============================== ================ + +In particular, ESC ( U is no longer "straight to font", since the font +might be completely different than the IBM character set. This +permits for example the use of block graphics even with a Latin-1 font +loaded. + +Note that although these codes are similar to ISO 2022, neither the +codes nor their uses match ISO 2022; Linux has two 8-bit codes (G0 and +G1), whereas ISO 2022 has four 7-bit codes (G0-G3). + +In accordance with the Unicode standard/ISO 10646 the range U+F000 to +U+F8FF has been reserved for OS-wide allocation (the Unicode Standard +refers to this as a "Corporate Zone", since this is inaccurate for +Linux we call it the "Linux Zone"). U+F000 was picked as the starting +point since it lets the direct-mapping area start on a large power of +two (in case 1024- or 2048-character fonts ever become necessary). +This leaves U+E000 to U+EFFF as End User Zone. + +[v1.2]: The Unicodes range from U+F000 and up to U+F7FF have been +hard-coded to map directly to the loaded font, bypassing the +translation table. The user-defined map now defaults to U+F000 to +U+F0FF, emulating the previous behaviour. In practice, this range +might be shorter; for example, vgacon can only handle 256-character +(U+F000..U+F0FF) or 512-character (U+F000..U+F1FF) fonts. + + +Actual characters assigned in the Linux Zone +-------------------------------------------- + +In addition, the following characters not present in Unicode 1.1.4 +have been defined; these are used by the DEC VT graphics map. [v1.2] +THIS USE IS OBSOLETE AND SHOULD NO LONGER BE USED; PLEASE SEE BELOW. + +====== ====================================== +U+F800 DEC VT GRAPHICS HORIZONTAL LINE SCAN 1 +U+F801 DEC VT GRAPHICS HORIZONTAL LINE SCAN 3 +U+F803 DEC VT GRAPHICS HORIZONTAL LINE SCAN 7 +U+F804 DEC VT GRAPHICS HORIZONTAL LINE SCAN 9 +====== ====================================== + +The DEC VT220 uses a 6x10 character matrix, and these characters form +a smooth progression in the DEC VT graphics character set. I have +omitted the scan 5 line, since it is also used as a block-graphics +character, and hence has been coded as U+2500 FORMS LIGHT HORIZONTAL. + +[v1.3]: These characters have been officially added to Unicode 3.2.0; +they are added at U+23BA, U+23BB, U+23BC, U+23BD. Linux now uses the +new values. + +[v1.2]: The following characters have been added to represent common +keyboard symbols that are unlikely to ever be added to Unicode proper +since they are horribly vendor-specific. This, of course, is an +excellent example of horrible design. + +====== ====================================== +U+F810 KEYBOARD SYMBOL FLYING FLAG +U+F811 KEYBOARD SYMBOL PULLDOWN MENU +U+F812 KEYBOARD SYMBOL OPEN APPLE +U+F813 KEYBOARD SYMBOL SOLID APPLE +====== ====================================== + +Klingon language support +------------------------ + +In 1996, Linux was the first operating system in the world to add +support for the artificial language Klingon, created by Marc Okrand +for the "Star Trek" television series. This encoding was later +adopted by the ConScript Unicode Registry and proposed (but ultimately +rejected) for inclusion in Unicode Plane 1. Thus, it remains as a +Linux/CSUR private assignment in the Linux Zone. + +This encoding has been endorsed by the Klingon Language Institute. +For more information, contact them at: + + http://www.kli.org/ + +Since the characters in the beginning of the Linux CZ have been more +of the dingbats/symbols/forms type and this is a language, I have +located it at the end, on a 16-cell boundary in keeping with standard +Unicode practice. + +.. note:: + + This range is now officially managed by the ConScript Unicode + Registry. The normative reference is at: + + http://www.evertype.com/standards/csur/klingon.html + +Klingon has an alphabet of 26 characters, a positional numeric writing +system with 10 digits, and is written left-to-right, top-to-bottom. + +Several glyph forms for the Klingon alphabet have been proposed. +However, since the set of symbols appear to be consistent throughout, +with only the actual shapes being different, in keeping with standard +Unicode practice these differences are considered font variants. + +====== ======================================================= +U+F8D0 KLINGON LETTER A +U+F8D1 KLINGON LETTER B +U+F8D2 KLINGON LETTER CH +U+F8D3 KLINGON LETTER D +U+F8D4 KLINGON LETTER E +U+F8D5 KLINGON LETTER GH +U+F8D6 KLINGON LETTER H +U+F8D7 KLINGON LETTER I +U+F8D8 KLINGON LETTER J +U+F8D9 KLINGON LETTER L +U+F8DA KLINGON LETTER M +U+F8DB KLINGON LETTER N +U+F8DC KLINGON LETTER NG +U+F8DD KLINGON LETTER O +U+F8DE KLINGON LETTER P +U+F8DF KLINGON LETTER Q + - Written <q> in standard Okrand Latin transliteration +U+F8E0 KLINGON LETTER QH + - Written <Q> in standard Okrand Latin transliteration +U+F8E1 KLINGON LETTER R +U+F8E2 KLINGON LETTER S +U+F8E3 KLINGON LETTER T +U+F8E4 KLINGON LETTER TLH +U+F8E5 KLINGON LETTER U +U+F8E6 KLINGON LETTER V +U+F8E7 KLINGON LETTER W +U+F8E8 KLINGON LETTER Y +U+F8E9 KLINGON LETTER GLOTTAL STOP + +U+F8F0 KLINGON DIGIT ZERO +U+F8F1 KLINGON DIGIT ONE +U+F8F2 KLINGON DIGIT TWO +U+F8F3 KLINGON DIGIT THREE +U+F8F4 KLINGON DIGIT FOUR +U+F8F5 KLINGON DIGIT FIVE +U+F8F6 KLINGON DIGIT SIX +U+F8F7 KLINGON DIGIT SEVEN +U+F8F8 KLINGON DIGIT EIGHT +U+F8F9 KLINGON DIGIT NINE + +U+F8FD KLINGON COMMA +U+F8FE KLINGON FULL STOP +U+F8FF KLINGON SYMBOL FOR EMPIRE +====== ======================================================= + +Other Fictional and Artificial Scripts +-------------------------------------- + +Since the assignment of the Klingon Linux Unicode block, a registry of +fictional and artificial scripts has been established by John Cowan +<jcowan@reutershealth.com> and Michael Everson <everson@evertype.com>. +The ConScript Unicode Registry is accessible at: + + http://www.evertype.com/standards/csur/ + +The ranges used fall at the low end of the End User Zone and can hence +not be normatively assigned, but it is recommended that people who +wish to encode fictional scripts use these codes, in the interest of +interoperability. For Klingon, CSUR has adopted the Linux encoding. +The CSUR people are driving adding Tengwar and Cirth into Unicode +Plane 1; the addition of Klingon to Unicode Plane 1 has been rejected +and so the above encoding remains official. diff --git a/Documentation/admin-guide/vga-softcursor.rst b/Documentation/admin-guide/vga-softcursor.rst new file mode 100644 index 000000000000..f52175457e60 --- /dev/null +++ b/Documentation/admin-guide/vga-softcursor.rst @@ -0,0 +1,62 @@ +Software cursor for VGA +======================= + +by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz> +and Martin Mares <mj@atrey.karlin.mff.cuni.cz> + +Linux now has some ability to manipulate cursor appearance. Normally, +you can set the size of hardware cursor. You can now play a few new +tricks: you can make your cursor look like a non-blinking red block, +make it inverse background of the character it's over or to highlight +that character and still choose whether the original hardware cursor +should remain visible or not. There may be other things I have never +thought of. + +The cursor appearance is controlled by a ``<ESC>[?1;2;3c`` escape sequence +where 1, 2 and 3 are parameters described below. If you omit any of them, +they will default to zeroes. + +first Parameter + specifies cursor size:: + + 0=default + 1=invisible + 2=underline, + ... + 8=full block + + 16 if you want the software cursor to be applied + + 32 if you want to always change the background color + + 64 if you dislike having the background the same as the + foreground. + + Highlights are ignored for the last two flags. + +second parameter + selects character attribute bits you want to change + (by simply XORing them with the value of this parameter). On standard + VGA, the high four bits specify background and the low four the + foreground. In both groups, low three bits set color (as in normal + color codes used by the console) and the most significant one turns + on highlight (or sometimes blinking -- it depends on the configuration + of your VGA). + +third parameter + consists of character attribute bits you want to set. + + Bit setting takes place before bit toggling, so you can simply clear a + bit by including it in both the set mask and the toggle mask. + +Examples +-------- + +To get normal blinking underline, use:: + + echo -e '\033[?2c' + +To get blinking block, use:: + + echo -e '\033[?6c' + +To get red non-blinking block, use:: + + echo -e '\033[?17;0;64c' |