mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-28 03:40:04 +00:00
91a9d50219
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>
87 lines
3 KiB
ReStructuredText
87 lines
3 KiB
ReStructuredText
==============================
|
|
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
|
|
-----
|
|
|
|
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. ::
|
|
|
|
make CC=clang defconfig
|
|
|
|
make CC=clang
|
|
|
|
Cross Compiling
|
|
---------------
|
|
|
|
A single Clang compiler binary will typically contain all supported backends,
|
|
which can help simplify cross compiling. ::
|
|
|
|
ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make CC=clang
|
|
|
|
``CROSS_COMPILE`` is not used to prefix the Clang compiler binary, instead
|
|
``CROSS_COMPILE`` is used to set a command line flag: ``--target <triple>``. For
|
|
example: ::
|
|
|
|
clang --target aarch64-linux-gnu foo.c
|
|
|
|
LLVM Utilities
|
|
--------------
|
|
|
|
LLVM has substitutes for GNU binutils utilities. Kbuild supports ``LLVM=1``
|
|
to enable them. ::
|
|
|
|
make LLVM=1
|
|
|
|
They can be enabled individually. The full list of the parameters: ::
|
|
|
|
make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \
|
|
OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump OBJSIZE=llvm-size \
|
|
READELF=llvm-readelf HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar \
|
|
HOSTLD=ld.lld
|
|
|
|
Currently, the integrated assembler is disabled by default. You can pass
|
|
``LLVM_IAS=1`` to enable it.
|
|
|
|
Getting Help
|
|
------------
|
|
|
|
- `Website <https://clangbuiltlinux.github.io/>`_
|
|
- `Mailing List <https://groups.google.com/forum/#!forum/clang-built-linux>`_: <clang-built-linux@googlegroups.com>
|
|
- `Issue Tracker <https://github.com/ClangBuiltLinux/linux/issues>`_
|
|
- IRC: #clangbuiltlinux on chat.freenode.net
|
|
- `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>`_
|
|
|
|
Getting LLVM
|
|
-------------
|
|
|
|
- https://releases.llvm.org/download.html
|
|
- 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/
|