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2023-03-30docs: move x86 documentation into Documentation/arch/Jonathan Corbet1-1443/+0
Move the x86 documentation under Documentation/arch/ as a way of cleaning up the top-level directory and making the structure of our docs more closely match the structure of the source directories it describes. All in-kernel references to the old paths have been updated. Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org Cc: Borislav Petkov <bp@alien8.de> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/lkml/20230315211523.108836-1-corbet@lwn.net/ Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2022-10-17Documentation/x86/boot: Reserve type_of_loader=13 for bareboxAhmad Fatoum1-0/+1
barebox[1], a bootloader for mostly ARM and MIPS embedded systems, can also be built as EFI payload for x86[2] to provide redundant power-fail safe, watchdog-supervised boot up. Since its v2015.09.0 release, it has been booting Linux on x86 with type_of_loader=0xff[3]. Reserve 13, the next free id, so that can be used instead in the future. [1]: https://www.barebox.org/ [2]: https://www.barebox.org/doc/latest/boards/efi.html [3]: https://elixir.bootlin.com/barebox/v2022.09.0/source/common/efi/payload/image.c#L217 Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20221002125752.3400831-1-a.fatoum@pengutronix.de
2021-06-17docs: x86: avoid using ReST :doc:`foo` markupMauro Carvalho Chehab1-2/+2
The :doc:`foo` tag is auto-generated via automarkup.py. So, use the filename at the sources, instead of :doc:`foo`. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/17c68b5f1d72488431c77c1de9f13683fe9f536c.1623824363.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-01-28Documentation/x86/boot.rst: Correct the example of SETUP_INDIRECTCao jin1-1/+1
struct setup_data.len is the length of data field. In case of SETUP_INDIRECT, it should be sizeof(setup_indirect). Signed-off-by: Cao jin <jojing64@gmail.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> Link: https://lore.kernel.org/r/20210127084911.63438-1-jojing64@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-10-02Documentation/x86: Fix incorrect references to zero-page.txtHeinrich Schuchardt1-3/+3
The file zero-page.txt does not exit. Add links to zero-page.rst instead. [ bp: Massage a bit. ] Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20201002190623.7489-1-xypron.glpk@gmx.de
2020-07-31x86: Add support for ZSTD compressed kernelNick Terrell1-3/+3
- Add support for zstd compressed kernel - Define __DISABLE_EXPORTS in Makefile - Remove __DISABLE_EXPORTS definition from kaslr.c - Bump the heap size for zstd. - Update the documentation. Integrates the ZSTD decompression code to the x86 pre-boot code. Zstandard requires slightly more memory during the kernel decompression on x86 (192 KB vs 64 KB), and the memory usage is independent of the window size. __DISABLE_EXPORTS is now defined in the Makefile, which covers both the existing use in kaslr.c, and the use needed by the zstd decompressor in misc.c. This patch has been boot tested with both a zstd and gzip compressed kernel on i386 and x86_64 using buildroot and QEMU. Additionally, this has been tested in production on x86_64 devices. We saw a 2 second boot time reduction by switching kernel compression from xz to zstd. Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20200730190841.2071656-7-nickrterrell@gmail.com
2020-04-14Documentation/x86, efi/x86: Clarify EFI handover protocol and its requirementsArd Biesheuvel1-3/+18
The EFI handover protocol was introduced on x86 to permit the boot loader to pass a populated boot_params structure as an additional function argument to the entry point. This allows the bootloader to pass the base and size of a initrd image, which is more flexible than relying on the EFI stub's file I/O routines, which can only access the file system from which the kernel image itself was loaded from firmware. This approach requires a fair amount of internal knowledge regarding the layout of the boot_params structure on the part of the boot loader, as well as knowledge regarding the allowed placement of the initrd in memory, and so it has been deprecated in favour of a new initrd loading method that is based on existing UEFI protocols and best practices. So update the x86 boot protocol documentation to clarify that the EFI handover protocol has been deprecated, and while at it, add a note that invoking the EFI handover protocol still requires the PE/COFF image to be loaded properly (as opposed to simply being copied into memory). Also, drop the code32_start header field from the list of values that need to be provided, as this is no longer required. Reviewed-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200409130434.6736-7-ardb@kernel.org
2020-02-22x86/boot: Remove KEEP_SEGMENTS supportArvind Sankar1-6/+2
Commit a24e785111a3 ("i386: paravirt boot sequence") added this flag for use by paravirtualized environments such as Xen. However, Xen never made use of this flag [1], and it was only ever used by lguest [2]. Commit ecda85e70277 ("x86/lguest: Remove lguest support") removed lguest, so KEEP_SEGMENTS has lost its last user. [1] https://lore.kernel.org/lkml/4D4B097C.5050405@goop.org [2] https://www.mail-archive.com/lguest@lists.ozlabs.org/msg00469.html Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200202171353.3736319-2-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-01-29Merge tag 'docs-5.6' of git://git.lwn.net/linuxLinus Torvalds1-22/+23
Pull documentation updates from Jonathan Corbet: "It has been a relatively quiet cycle for documentation, but there's still a couple of things of note: - Conversion of the NFS documentation to RST - A new document on how to help with documentation (and a maintainer profile entry too) Plus the usual collection of typo fixes, etc" * tag 'docs-5.6' of git://git.lwn.net/linux: (40 commits) docs: filesystems: add overlayfs to index.rst docs: usb: remove some broken references scripts/find-unused-docs: Fix massive false positives docs: nvdimm: use ReST notation for subsection zram: correct documentation about sysfs node of huge page writeback Documentation: zram: various fixes in zram.rst Add a maintainer entry profile for documentation Add a document on how to contribute to the documentation docs: Keep up with the location of NoUri Documentation: Call out example SYM_FUNC_* usage as x86-specific Documentation: nfs: fault_injection: convert to ReST Documentation: nfs: pnfs-scsi-server: convert to ReST Documentation: nfs: convert pnfs-block-server to ReST Documentation: nfs: idmapper: convert to ReST Documentation: convert nfsd-admin-interfaces to ReST Documentation: nfs-rdma: convert to ReST Documentation: nfsroot.rst: COSMETIC: refill a paragraph Documentation: nfsroot.txt: convert to ReST Documentation: convert nfs.txt to ReST Documentation: filesystems: convert vfat.txt to RST ...
2020-01-10Documentation: boot.rst: fix warningsDaniel W. S. Almeida1-20/+20
Fix WARNING: Inline emphasis start-string without end-string. This warning was due to wrong syntax being used. Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com> Link: https://lore.kernel.org/r/20191223033121.1584930-1-dwlsalmeida@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-12-19Documentation: x86: fix boot.rst warning and formatRandy Dunlap1-2/+3
Fix a Sphinx documentation format warning by breaking a long line into 2 lines. Also drop the ':' usage after the Protocol version numbers since other Protocol versions don't use colons. Documentation/x86/boot.rst:72: WARNING: Malformed table. Text in column margin in table line 57. Fixes: 2c33c27fd603 ("x86/boot: Introduce kernel_info") Fixes: 00cd1c154d56 ("x86/boot: Introduce kernel_info.setup_type_max") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Link: https://lore.kernel.org/r/c6fbf592-0aca-69d9-e903-e869221a041a@infradead.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-12-18Documentation/x86/boot: Fix typoEnrico Weigelt1-1/+1
s/Fileds/Fields/g Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20191203113314.26810-1-info@metux.net
2019-11-12x86/boot: Introduce setup_indirectDaniel Kiper1-1/+42
The setup_data is a bit awkward to use for extremely large data objects, both because the setup_data header has to be adjacent to the data object and because it has a 32-bit length field. However, it is important that intermediate stages of the boot process have a way to identify which chunks of memory are occupied by kernel data. Thus introduce an uniform way to specify such indirect data as setup_indirect struct and SETUP_INDIRECT type. And finally bump setup_header version in arch/x86/boot/header.S. Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Ross Philipson <ross.philipson@oracle.com> Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: ard.biesheuvel@linaro.org Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: dave.hansen@linux.intel.com Cc: eric.snowberg@oracle.com Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Juergen Gross <jgross@suse.com> Cc: kanth.ghatraju@oracle.com Cc: linux-doc@vger.kernel.org Cc: linux-efi <linux-efi@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rdunlap@infradead.org Cc: ross.philipson@oracle.com Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Cc: xen-devel@lists.xenproject.org Link: https://lkml.kernel.org/r/20191112134640.16035-4-daniel.kiper@oracle.com
2019-11-12x86/boot: Introduce kernel_info.setup_type_maxDaniel Kiper1-1/+8
This field contains maximal allowed type for setup_data. Do not bump setup_header version in arch/x86/boot/header.S because it will be followed by additional changes coming into the Linux/x86 boot protocol. Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reviewed-by: Ross Philipson <ross.philipson@oracle.com> Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: ard.biesheuvel@linaro.org Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: dave.hansen@linux.intel.com Cc: eric.snowberg@oracle.com Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Juergen Gross <jgross@suse.com> Cc: kanth.ghatraju@oracle.com Cc: linux-doc@vger.kernel.org Cc: linux-efi <linux-efi@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rdunlap@infradead.org Cc: ross.philipson@oracle.com Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Cc: xen-devel@lists.xenproject.org Link: https://lkml.kernel.org/r/20191112134640.16035-3-daniel.kiper@oracle.com
2019-11-12x86/boot: Introduce kernel_infoDaniel Kiper1-0/+126
The relationships between the headers are analogous to the various data sections: setup_header = .data boot_params/setup_data = .bss What is missing from the above list? That's right: kernel_info = .rodata We have been (ab)using .data for things that could go into .rodata or .bss for a long time, for lack of alternatives and -- especially early on -- inertia. Also, the BIOS stub is responsible for creating boot_params, so it isn't available to a BIOS-based loader (setup_data is, though). setup_header is permanently limited to 144 bytes due to the reach of the 2-byte jump field, which doubles as a length field for the structure, combined with the size of the "hole" in struct boot_params that a protected-mode loader or the BIOS stub has to copy it into. It is currently 119 bytes long, which leaves us with 25 very precious bytes. This isn't something that can be fixed without revising the boot protocol entirely, breaking backwards compatibility. boot_params proper is limited to 4096 bytes, but can be arbitrarily extended by adding setup_data entries. It cannot be used to communicate properties of the kernel image, because it is .bss and has no image-provided content. kernel_info solves this by providing an extensible place for information about the kernel image. It is readonly, because the kernel cannot rely on a bootloader copying its contents anywhere, but that is OK; if it becomes necessary it can still contain data items that an enabled bootloader would be expected to copy into a setup_data chunk. Do not bump setup_header version in arch/x86/boot/header.S because it will be followed by additional changes coming into the Linux/x86 boot protocol. Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reviewed-by: Ross Philipson <ross.philipson@oracle.com> Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: ard.biesheuvel@linaro.org Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: dave.hansen@linux.intel.com Cc: eric.snowberg@oracle.com Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Juergen Gross <jgross@suse.com> Cc: kanth.ghatraju@oracle.com Cc: linux-doc@vger.kernel.org Cc: linux-efi <linux-efi@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rdunlap@infradead.org Cc: ross.philipson@oracle.com Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Cc: xen-devel@lists.xenproject.org Link: https://lkml.kernel.org/r/20191112134640.16035-2-daniel.kiper@oracle.com
2019-05-08Documentation: x86: convert boot.txt to reSTChangbin Du1-0/+1256
This converts the plain text documentation to reStructuredText format and add it to Sphinx TOC tree. No essential content change. Signed-off-by: Changbin Du <changbin.du@gmail.com> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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