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WSL2-Linux-Kernel/Documentation/kbuild/llvm.rst

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Documentation: add minimum clang/llvm version Based on a vote at the LLVM BoF at Plumbers 2020, we decided to start small, supporting just one formal upstream release of LLVM for now. We can probably widen the support window of supported versions over time. Also, note that LLVM's release process is different than GCC's. GCC tends to have 1 major release per year while releasing minor updates to the past 3 major versions. LLVM tends to support one major release and one minor release every six months. Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Gustavo A. R. Silva <gustavoars@kernel.org> Tested-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20200826191555.3350406-1-ndesaulniers@google.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-08-26 22:15:55 +03:00
.. _kbuild_llvm:
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
==============================
Building Linux with Clang/LLVM
==============================
This document covers how to build the Linux kernel with Clang and LLVM
utilities.
About
-----
The Linux kernel has always traditionally been compiled with GNU toolchains
such as GCC and binutils. Ongoing work has allowed for `Clang
<https://clang.llvm.org/>`_ and `LLVM <https://llvm.org/>`_ utilities to be
used as viable substitutes. Distributions such as `Android
<https://www.android.com/>`_, `ChromeOS
<https://www.chromium.org/chromium-os>`_, and `OpenMandriva
<https://www.openmandriva.org/>`_ use Clang built kernels. `LLVM is a
collection of toolchain components implemented in terms of C++ objects
<https://www.aosabook.org/en/llvm.html>`_. Clang is a front-end to LLVM that
supports C and the GNU C extensions required by the kernel, and is pronounced
"klang," not "see-lang."
Clang
-----
Documentation/llvm: Improve formatting of commands, variables, and arguments While reviewing a separate patch, I noticed that the formatting of the commands, variables, and arguments was not in a monospaced font like the rest of the Kbuild documentation (see kbuild/kconfig.rst for an example). This is due to a lack of "::" before indented command blocks and single backticks instead of double backticks for inline formatting. Add those so that the document looks nicer in an HTML format, while not ruining the look in plain text. As a result of this, we can remove the escaped backslashes in the last code block and move them to single backslashes. Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-08-26 02:14:38 +03:00
The compiler used can be swapped out via ``CC=`` command line argument to ``make``.
``CC=`` should be set when selecting a config and during a build. ::
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
make CC=clang defconfig
make CC=clang
Cross Compiling
---------------
A single Clang compiler binary will typically contain all supported backends,
Documentation/llvm: Improve formatting of commands, variables, and arguments While reviewing a separate patch, I noticed that the formatting of the commands, variables, and arguments was not in a monospaced font like the rest of the Kbuild documentation (see kbuild/kconfig.rst for an example). This is due to a lack of "::" before indented command blocks and single backticks instead of double backticks for inline formatting. Add those so that the document looks nicer in an HTML format, while not ruining the look in plain text. As a result of this, we can remove the escaped backslashes in the last code block and move them to single backslashes. Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-08-26 02:14:38 +03:00
which can help simplify cross compiling. ::
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
Documentation/llvm: update CROSS_COMPILE inferencing As noted by Masahiro, document how we can generally infer CROSS_COMPILE (and the more specific details about --target and --prefix) based on ARCH. Change use of env vars to command line parameters. Suggested-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Fangrui Song <maskray@google.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-08-02 21:39:10 +03:00
make ARCH=arm64 CC=clang CROSS_COMPILE=aarch64-linux-gnu-
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
Documentation/llvm: Improve formatting of commands, variables, and arguments While reviewing a separate patch, I noticed that the formatting of the commands, variables, and arguments was not in a monospaced font like the rest of the Kbuild documentation (see kbuild/kconfig.rst for an example). This is due to a lack of "::" before indented command blocks and single backticks instead of double backticks for inline formatting. Add those so that the document looks nicer in an HTML format, while not ruining the look in plain text. As a result of this, we can remove the escaped backslashes in the last code block and move them to single backslashes. Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-08-26 02:14:38 +03:00
``CROSS_COMPILE`` is not used to prefix the Clang compiler binary, instead
Documentation/llvm: Fix clang target examples clang --target=<triple> is how we can specify a particular toolchain triple to be use, fix the two occurences in the documentation. Fixes: fcf1b6a35c16 ("Documentation/llvm: add documentation on building w/ Clang/LLVM") Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-09-25 18:21:14 +03:00
``CROSS_COMPILE`` is used to set a command line flag: ``--target=<triple>``. For
Documentation/llvm: Improve formatting of commands, variables, and arguments While reviewing a separate patch, I noticed that the formatting of the commands, variables, and arguments was not in a monospaced font like the rest of the Kbuild documentation (see kbuild/kconfig.rst for an example). This is due to a lack of "::" before indented command blocks and single backticks instead of double backticks for inline formatting. Add those so that the document looks nicer in an HTML format, while not ruining the look in plain text. As a result of this, we can remove the escaped backslashes in the last code block and move them to single backslashes. Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-08-26 02:14:38 +03:00
example: ::
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
Documentation/llvm: Fix clang target examples clang --target=<triple> is how we can specify a particular toolchain triple to be use, fix the two occurences in the documentation. Fixes: fcf1b6a35c16 ("Documentation/llvm: add documentation on building w/ Clang/LLVM") Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-09-25 18:21:14 +03:00
clang --target=aarch64-linux-gnu foo.c
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
LLVM Utilities
--------------
Documentation/llvm: Improve formatting of commands, variables, and arguments While reviewing a separate patch, I noticed that the formatting of the commands, variables, and arguments was not in a monospaced font like the rest of the Kbuild documentation (see kbuild/kconfig.rst for an example). This is due to a lack of "::" before indented command blocks and single backticks instead of double backticks for inline formatting. Add those so that the document looks nicer in an HTML format, while not ruining the look in plain text. As a result of this, we can remove the escaped backslashes in the last code block and move them to single backslashes. Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-08-26 02:14:38 +03:00
LLVM has substitutes for GNU binutils utilities. Kbuild supports ``LLVM=1``
to enable them. ::
kbuild: support LLVM=1 to switch the default tools to Clang/LLVM As Documentation/kbuild/llvm.rst implies, building the kernel with a full set of LLVM tools gets very verbose and unwieldy. Provide a single switch LLVM=1 to use Clang and LLVM tools instead of GCC and Binutils. You can pass it from the command line or as an environment variable. Please note LLVM=1 does not turn on the integrated assembler. You need to pass LLVM_IAS=1 to use it. When the upstream kernel is ready for the integrated assembler, I think we can make it default. We discussed what we need, and we agreed to go with a simple boolean flag that switches both target and host tools: https://lkml.org/lkml/2020/3/28/494 https://lkml.org/lkml/2020/4/3/43 Some items discussed, but not adopted: - LLVM_DIR When multiple versions of LLVM are installed, I just thought supporting LLVM_DIR=/path/to/my/llvm/bin/ might be useful. CC = $(LLVM_DIR)clang LD = $(LLVM_DIR)ld.lld ... However, we can handle this by modifying PATH. So, we decided to not do this. - LLVM_SUFFIX Some distributions (e.g. Debian) package specific versions of LLVM with naming conventions that use the version as a suffix. CC = clang$(LLVM_SUFFIX) LD = ld.lld(LLVM_SUFFIX) ... will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc., but the suffixed versions in /usr/bin/ are symlinks to binaries in /usr/lib/llvm-#/bin/, so this can also be handled by PATH. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Tested-by: Nathan Chancellor <natechancellor@gmail.com> # build Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2020-04-08 04:36:23 +03:00
make LLVM=1
Documentation/llvm: Improve formatting of commands, variables, and arguments While reviewing a separate patch, I noticed that the formatting of the commands, variables, and arguments was not in a monospaced font like the rest of the Kbuild documentation (see kbuild/kconfig.rst for an example). This is due to a lack of "::" before indented command blocks and single backticks instead of double backticks for inline formatting. Add those so that the document looks nicer in an HTML format, while not ruining the look in plain text. As a result of this, we can remove the escaped backslashes in the last code block and move them to single backslashes. Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-08-26 02:14:38 +03:00
They can be enabled individually. The full list of the parameters: ::
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
Documentation/llvm: Improve formatting of commands, variables, and arguments While reviewing a separate patch, I noticed that the formatting of the commands, variables, and arguments was not in a monospaced font like the rest of the Kbuild documentation (see kbuild/kconfig.rst for an example). This is due to a lack of "::" before indented command blocks and single backticks instead of double backticks for inline formatting. Add those so that the document looks nicer in an HTML format, while not ruining the look in plain text. As a result of this, we can remove the escaped backslashes in the last code block and move them to single backslashes. Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-08-26 02:14:38 +03:00
make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \
kbuild: remove unused OBJSIZE The "size" tool has been solely used by s390 to enforce .bss section usage restrictions in early startup code. Since commit 980d5f9ab36b ("s390/boot: enable .bss section for compressed kernel") and commit 2e83e0eb85ca ("s390: clean .bss before running uncompressed kernel") these restrictions have been lifted for the decompressor and uncompressed kernel and the size tool is now unused. Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-10-23 14:57:32 +03:00
OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump READELF=llvm-readelf \
HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar HOSTLD=ld.lld
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
scripts/Makefile.clang: default to LLVM_IAS=1 LLVM_IAS=1 controls enabling clang's integrated assembler via -integrated-as. This was an explicit opt in until we could enable assembler support in Clang for more architecures. Now we have support and CI coverage of LLVM_IAS=1 for all architecures except a few more bugs affecting s390 and powerpc. This commit flips the default from opt in via LLVM_IAS=1 to opt out via LLVM_IAS=0. CI systems or developers that were previously doing builds with CC=clang or LLVM=1 without explicitly setting LLVM_IAS must now explicitly opt out via LLVM_IAS=0, otherwise they will be implicitly opted-in. This finally shortens the command line invocation when cross compiling with LLVM to simply: $ make ARCH=arm64 LLVM=1 Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-08-06 20:27:01 +03:00
The integrated assembler is enabled by default. You can pass ``LLVM_IAS=0`` to
disable it.
kbuild: replace AS=clang with LLVM_IAS=1 The 'AS' variable is unused for building the kernel. Only the remaining usage is to turn on the integrated assembler. A boolean flag is a better fit for this purpose. AS=clang was added for experts. So, I replaced it with LLVM_IAS=1, breaking the backward compatibility. Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2020-04-08 04:36:22 +03:00
Documentation/llvm: update CROSS_COMPILE inferencing As noted by Masahiro, document how we can generally infer CROSS_COMPILE (and the more specific details about --target and --prefix) based on ARCH. Change use of env vars to command line parameters. Suggested-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Fangrui Song <maskray@google.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-08-02 21:39:10 +03:00
Omitting CROSS_COMPILE
----------------------
As explained above, ``CROSS_COMPILE`` is used to set ``--target=<triple>``.
If ``CROSS_COMPILE`` is not specified, the ``--target=<triple>`` is inferred
from ``ARCH``.
That means if you use only LLVM tools, ``CROSS_COMPILE`` becomes unnecessary.
For example, to cross-compile the arm64 kernel::
scripts/Makefile.clang: default to LLVM_IAS=1 LLVM_IAS=1 controls enabling clang's integrated assembler via -integrated-as. This was an explicit opt in until we could enable assembler support in Clang for more architecures. Now we have support and CI coverage of LLVM_IAS=1 for all architecures except a few more bugs affecting s390 and powerpc. This commit flips the default from opt in via LLVM_IAS=1 to opt out via LLVM_IAS=0. CI systems or developers that were previously doing builds with CC=clang or LLVM=1 without explicitly setting LLVM_IAS must now explicitly opt out via LLVM_IAS=0, otherwise they will be implicitly opted-in. This finally shortens the command line invocation when cross compiling with LLVM to simply: $ make ARCH=arm64 LLVM=1 Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-08-06 20:27:01 +03:00
make ARCH=arm64 LLVM=1
If ``LLVM_IAS=0`` is specified, ``CROSS_COMPILE`` is also used to derive
``--prefix=<path>`` to search for the GNU assembler and linker. ::
make ARCH=arm64 LLVM=1 LLVM_IAS=0 CROSS_COMPILE=aarch64-linux-gnu-
Documentation/llvm: update CROSS_COMPILE inferencing As noted by Masahiro, document how we can generally infer CROSS_COMPILE (and the more specific details about --target and --prefix) based on ARCH. Change use of env vars to command line parameters. Suggested-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Fangrui Song <maskray@google.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-08-02 21:39:10 +03:00
Documentation/llvm: Add a section about supported architectures The most common question around building the Linux kernel with clang is "does it work?" and the answer has always been "it depends on your architecture, configuration, and LLVM version" with no hard answers for users wanting to experiment. LLVM support has significantly improved over the past couple of years, resulting in more architectures and configurations supported, and continuous integration has made it easier to see what works and what does not. Add a section that goes over what architectures are supported in the current kernel version, how they should be built (with just clang or the LLVM utilities as well), and the level of support they receive. This will make it easier for people to try out building their kernel with LLVM and reporting issues that come about from it. Suggested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulnier@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-01-14 03:34:47 +03:00
Supported Architectures
-----------------------
LLVM does not target all of the architectures that Linux supports and
just because a target is supported in LLVM does not mean that the kernel
will build or work without any issues. Below is a general summary of
architectures that currently work with ``CC=clang`` or ``LLVM=1``. Level
of support corresponds to "S" values in the MAINTAINERS files. If an
architecture is not present, it either means that LLVM does not target
it or there are known issues. Using the latest stable version of LLVM or
even the development tree will generally yield the best results.
An architecture's ``defconfig`` is generally expected to work well,
certain configurations may have problems that have not been uncovered
yet. Bug reports are always welcome at the issue tracker below!
.. list-table::
:widths: 10 10 10
:header-rows: 1
* - Architecture
- Level of support
- ``make`` command
* - arm
- Supported
- ``LLVM=1``
* - arm64
- Supported
- ``LLVM=1``
* - mips
- Maintained
- ``CC=clang``
* - powerpc
- Maintained
- ``CC=clang``
* - riscv
- Maintained
- ``CC=clang``
* - s390
- Maintained
- ``CC=clang``
* - x86
- Supported
- ``LLVM=1``
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
Getting Help
------------
- `Website <https://clangbuiltlinux.github.io/>`_
Documentation/llvm: update mailing list We are now at llvm@lists.linux.dev. Link: https://lkml.kernel.org/r/20210825211823.6406-2-nathan@kernel.org Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-08 05:58:27 +03:00
- `Mailing List <https://lore.kernel.org/llvm/>`_: <llvm@lists.linux.dev>
- `Old Mailing List Archives <https://groups.google.com/g/clang-built-linux>`_
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
- `Issue Tracker <https://github.com/ClangBuiltLinux/linux/issues>`_
Documentation/llvm: update IRC location This should have been done with commit 91ed3ed0f798 ("MAINTAINERS: update ClangBuiltLinux IRC chat") but I did not realize it was in two separate spots. Link: https://lkml.kernel.org/r/20210825211823.6406-3-nathan@kernel.org Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-08 05:58:30 +03:00
- IRC: #clangbuiltlinux on irc.libera.chat
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
- `Telegram <https://t.me/ClangBuiltLinux>`_: @ClangBuiltLinux
- `Wiki <https://github.com/ClangBuiltLinux/linux/wiki>`_
- `Beginner Bugs <https://github.com/ClangBuiltLinux/linux/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22>`_
Documentation: add minimum clang/llvm version Based on a vote at the LLVM BoF at Plumbers 2020, we decided to start small, supporting just one formal upstream release of LLVM for now. We can probably widen the support window of supported versions over time. Also, note that LLVM's release process is different than GCC's. GCC tends to have 1 major release per year while releasing minor updates to the past 3 major versions. LLVM tends to support one major release and one minor release every six months. Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Gustavo A. R. Silva <gustavoars@kernel.org> Tested-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20200826191555.3350406-1-ndesaulniers@google.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-08-26 22:15:55 +03:00
.. _getting_llvm:
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
Getting LLVM
-------------
kbuild: Replace HTTP links with HTTPS ones Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-07-19 22:46:02 +03:00
- https://releases.llvm.org/download.html
Documentation/llvm: add documentation on building w/ Clang/LLVM Added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:23:36 +03:00
- https://github.com/llvm/llvm-project
- https://llvm.org/docs/GettingStarted.html
- https://llvm.org/docs/CMake.html
- https://apt.llvm.org/
- https://www.archlinux.org/packages/extra/x86_64/llvm/
- https://github.com/ClangBuiltLinux/tc-build
- https://github.com/ClangBuiltLinux/linux/wiki/Building-Clang-from-source
- https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/