docs: Sphinxify gdb-kernel-debugging.txt and move to dev-tools

Acked-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 0 insertions, 160 deletions

diff --git a/Documentation/gdb-kernel-debugging.txt b/Documentation/gdb-kernel-debugging.txt
deleted file mode 100644
index 7050ce8794b9..000000000000
--- a/Documentation/gdb-kernel-debugging.txt
+++ /dev/null
@@ -1,160 +0,0 @@
-Debugging kernel and modules via gdb
-====================================
-
-The kernel debugger kgdb, hypervisors like QEMU or JTAG-based hardware
-interfaces allow to debug the Linux kernel and its modules during runtime
-using gdb. Gdb comes with a powerful scripting interface for python. The
-kernel provides a collection of helper scripts that can simplify typical
-kernel debugging steps. This is a short tutorial about how to enable and use
-them. It focuses on QEMU/KVM virtual machines as target, but the examples can
-be transferred to the other gdb stubs as well.
-
-
-Requirements
-------------
-
- o gdb 7.2+ (recommended: 7.4+) with python support enabled (typically true
-   for distributions)
-
-
-Setup
------
-
- o Create a virtual Linux machine for QEMU/KVM (see www.linux-kvm.org and
-   www.qemu.org for more details). For cross-development,
-   http://landley.net/aboriginal/bin keeps a pool of machine images and
-   toolchains that can be helpful to start from.
-
- o Build the kernel with CONFIG_GDB_SCRIPTS enabled, but leave
-   CONFIG_DEBUG_INFO_REDUCED off. If your architecture supports
-   CONFIG_FRAME_POINTER, keep it enabled.
-
- o Install that kernel on the guest.
-
-   Alternatively, QEMU allows to boot the kernel directly using -kernel,
-   -append, -initrd command line switches. This is generally only useful if
-   you do not depend on modules. See QEMU documentation for more details on
-   this mode.
-
- o Enable the gdb stub of QEMU/KVM, either
-    - at VM startup time by appending "-s" to the QEMU command line
-   or
-    - during runtime by issuing "gdbserver" from the QEMU monitor
-      console
-
- o cd /path/to/linux-build
-
- o Start gdb: gdb vmlinux
-
-   Note: Some distros may restrict auto-loading of gdb scripts to known safe
-   directories. In case gdb reports to refuse loading vmlinux-gdb.py, add
-
-    add-auto-load-safe-path /path/to/linux-build
-
-   to ~/.gdbinit. See gdb help for more details.
-
- o Attach to the booted guest:
-    (gdb) target remote :1234
-
-
-Examples of using the Linux-provided gdb helpers
-------------------------------------------------
-
- o Load module (and main kernel) symbols:
-    (gdb) lx-symbols
-    loading vmlinux
-    scanning for modules in /home/user/linux/build
-    loading @0xffffffffa0020000: /home/user/linux/build/net/netfilter/xt_tcpudp.ko
-    loading @0xffffffffa0016000: /home/user/linux/build/net/netfilter/xt_pkttype.ko
-    loading @0xffffffffa0002000: /home/user/linux/build/net/netfilter/xt_limit.ko
-    loading @0xffffffffa00ca000: /home/user/linux/build/net/packet/af_packet.ko
-    loading @0xffffffffa003c000: /home/user/linux/build/fs/fuse/fuse.ko
-    ...
-    loading @0xffffffffa0000000: /home/user/linux/build/drivers/ata/ata_generic.ko
-
- o Set a breakpoint on some not yet loaded module function, e.g.:
-    (gdb) b btrfs_init_sysfs
-    Function "btrfs_init_sysfs" not defined.
-    Make breakpoint pending on future shared library load? (y or [n]) y
-    Breakpoint 1 (btrfs_init_sysfs) pending.
-
- o Continue the target
-    (gdb) c
-
- o Load the module on the target and watch the symbols being loaded as well as
-   the breakpoint hit:
-    loading @0xffffffffa0034000: /home/user/linux/build/lib/libcrc32c.ko
-    loading @0xffffffffa0050000: /home/user/linux/build/lib/lzo/lzo_compress.ko
-    loading @0xffffffffa006e000: /home/user/linux/build/lib/zlib_deflate/zlib_deflate.ko
-    loading @0xffffffffa01b1000: /home/user/linux/build/fs/btrfs/btrfs.ko
-
-    Breakpoint 1, btrfs_init_sysfs () at /home/user/linux/fs/btrfs/sysfs.c:36
-    36              btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
-
- o Dump the log buffer of the target kernel:
-    (gdb) lx-dmesg
-    [     0.000000] Initializing cgroup subsys cpuset
-    [     0.000000] Initializing cgroup subsys cpu
-    [     0.000000] Linux version 3.8.0-rc4-dbg+ (...
-    [     0.000000] Command line: root=/dev/sda2 resume=/dev/sda1 vga=0x314
-    [     0.000000] e820: BIOS-provided physical RAM map:
-    [     0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
-    [     0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved
-    ....
-
- o Examine fields of the current task struct:
-    (gdb) p $lx_current().pid
-    $1 = 4998
-    (gdb) p $lx_current().comm
-    $2 = "modprobe\000\000\000\000\000\000\000"
-
- o Make use of the per-cpu function for the current or a specified CPU:
-    (gdb) p $lx_per_cpu("runqueues").nr_running
-    $3 = 1
-    (gdb) p $lx_per_cpu("runqueues", 2).nr_running
-    $4 = 0
-
- o Dig into hrtimers using the container_of helper:
-    (gdb) set $next = $lx_per_cpu("hrtimer_bases").clock_base[0].active.next
-    (gdb) p *$container_of($next, "struct hrtimer", "node")
-    $5 = {
-      node = {
-        node = {
-          __rb_parent_color = 18446612133355256072,
-          rb_right = 0x0 <irq_stack_union>,
-          rb_left = 0x0 <irq_stack_union>
-        },
-        expires = {
-          tv64 = 1835268000000
-        }
-      },
-      _softexpires = {
-        tv64 = 1835268000000
-      },
-      function = 0xffffffff81078232 <tick_sched_timer>,
-      base = 0xffff88003fd0d6f0,
-      state = 1,
-      start_pid = 0,
-      start_site = 0xffffffff81055c1f <hrtimer_start_range_ns+20>,
-      start_comm = "swapper/2\000\000\000\000\000\000"
-    }
-
-
-List of commands and functions
-------------------------------
-
-The number of commands and convenience functions may evolve over the time,
-this is just a snapshot of the initial version:
-
- (gdb) apropos lx
- function lx_current -- Return current task
- function lx_module -- Find module by name and return the module variable
- function lx_per_cpu -- Return per-cpu variable
- function lx_task_by_pid -- Find Linux task by PID and return the task_struct variable
- function lx_thread_info -- Calculate Linux thread_info from task variable
- lx-dmesg -- Print Linux kernel log buffer
- lx-lsmod -- List currently loaded modules
- lx-symbols -- (Re-)load symbols of Linux kernel and currently loaded modules
-
-Detailed help can be obtained via "help <command-name>" for commands and "help
-function <function-name>" for convenience functions.