| Message ID | 20210114003447.7363-1-natechancellor@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Documentation/llvm: Add a section about supported architectures | expand |
On Wed, Jan 13, 2021 at 5:19 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > > Patch looks fine, but `make -j htmldocs` seems to be taking forever > for me so I can't render it. Is this a known issue? > > $ make -j htmldocs Just took a while, lots of warning spew (but not from this addition AFAICT). Reviewed-by: Nick Desaulniers <ndesaulnier@google.com> > > On Wed, Jan 13, 2021 at 4:35 PM Nathan Chancellor > <natechancellor@gmail.com> wrote: > > > > 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> > > --- > > Documentation/kbuild/llvm.rst | 44 +++++++++++++++++++++++++++++++++++ > > 1 file changed, 44 insertions(+) > > > > diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst > > index 21c847890d03..b18401d2ba82 100644 > > --- a/Documentation/kbuild/llvm.rst > > +++ b/Documentation/kbuild/llvm.rst > > @@ -63,6 +63,50 @@ They can be enabled individually. The full list of the parameters: :: > > Currently, the integrated assembler is disabled by default. You can pass > > ``LLVM_IAS=1`` to enable it. > > > > +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`` > > + > > Getting Help > > ------------ > > > > > > base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837 > > -- > > 2.30.0 > > > > > -- > Thanks, > ~Nick Desaulniers
On Wed, Jan 13, 2021 at 06:05:32PM -0800, Nick Desaulniers wrote: > On Wed, Jan 13, 2021 at 5:19 PM Nick Desaulniers > <ndesaulniers@google.com> wrote: > > > > Patch looks fine, but `make -j htmldocs` seems to be taking forever > > for me so I can't render it. Is this a known issue? > > > > $ make -j htmldocs A clean "make -skj24 htmldocs" takes me a little over three minutes or so on my Ryzen 9 3900X. Just to give some perspective. > Just took a while, lots of warning spew (but not from this addition AFAICT). > Reviewed-by: Nick Desaulniers <ndesaulnier@google.com> Thanks for the review! Cheers, Nathan
On Thu, Jan 14, 2021 at 1:35 AM Nathan Chancellor <natechancellor@gmail.com> wrote: > > 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. > Thanks, this was overdue and is definitely helpful for users and developers. For x86 64bit: Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Together with "[PATCH] kbuild: check the minimum compiler version in Kconfig" this looks very good to me. /o\ - Sedat - [1] https://marc.info/?t=161059811000001&r=1&w=2 > Suggested-by: Miguel Ojeda <ojeda@kernel.org> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > Documentation/kbuild/llvm.rst | 44 +++++++++++++++++++++++++++++++++++ > 1 file changed, 44 insertions(+) > > diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst > index 21c847890d03..b18401d2ba82 100644 > --- a/Documentation/kbuild/llvm.rst > +++ b/Documentation/kbuild/llvm.rst > @@ -63,6 +63,50 @@ They can be enabled individually. The full list of the parameters: :: > Currently, the integrated assembler is disabled by default. You can pass > ``LLVM_IAS=1`` to enable it. > > +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`` > + > Getting Help > ------------ > > > base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837 > -- > 2.30.0 > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210114003447.7363-1-natechancellor%40gmail.com.
On Thu, Jan 14, 2021 at 3:23 AM Nathan Chancellor <natechancellor@gmail.com> wrote: > > A clean "make -skj24 htmldocs" takes me a little over three minutes or > so on my Ryzen 9 3900X. Just to give some perspective. Oh, wow, that's something... Thanks a lot for adding this: Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Cheers, Miguel
On Wed, 13 Jan 2021 17:19:59 -0800 Nick Desaulniers <ndesaulniers@google.com> wrote: > Patch looks fine, but `make -j htmldocs` seems to be taking forever > for me so I can't render it. Is this a known issue? > > $ make -j htmldocs > SPHINX htmldocs --> file:///android0/linux-next/Documentation/output > make[2]: Nothing to be done for 'html'. > WARNING: The kernel documentation build process > support for Sphinx v3.0 and above is brand new. Be prepared for > possible issues in the generated output. Sphinx 3.x is *way* slower to build the docs, alas. One of many "improvements" we got with that change. jon
On Thu, Jan 14, 2021 at 6:36 AM Jonathan Corbet <corbet@lwn.net> wrote: > > On Wed, 13 Jan 2021 17:19:59 -0800 > Nick Desaulniers <ndesaulniers@google.com> wrote: > > > Patch looks fine, but `make -j htmldocs` seems to be taking forever > > for me so I can't render it. Is this a known issue? > > > > $ make -j htmldocs > > SPHINX htmldocs --> file:///android0/linux-next/Documentation/output > > make[2]: Nothing to be done for 'html'. > > WARNING: The kernel documentation build process > > support for Sphinx v3.0 and above is brand new. Be prepared for > > possible issues in the generated output. > > Sphinx 3.x is *way* slower to build the docs, alas. One of many > "improvements" we got with that change. Oh, man, yeah. Noticeably. I had sworn I had run `make htmldocs` before. Have you had a chance to report this regression upstream?
On Wed, Jan 13, 2021 at 05:34:47PM -0700, Nathan Chancellor wrote: > 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> Jonathan, did you need anything else from me on this, or does Masahiro need to pick this up? Cheers, Nathan
On Sat, Jan 30, 2021 at 5:31 AM Nathan Chancellor <nathan@kernel.org> wrote: > > On Wed, Jan 13, 2021 at 05:34:47PM -0700, Nathan Chancellor wrote: > > 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> > > Jonathan, did you need anything else from me on this, or does Masahiro > need to pick this up? > > Cheers, > Nathan Now I applied to linux-kbuild. Thanks for the reminder.
diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst index 21c847890d03..b18401d2ba82 100644 --- a/Documentation/kbuild/llvm.rst +++ b/Documentation/kbuild/llvm.rst @@ -63,6 +63,50 @@ They can be enabled individually. The full list of the parameters: :: Currently, the integrated assembler is disabled by default. You can pass ``LLVM_IAS=1`` to enable it. +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`` + Getting Help ------------
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> --- Documentation/kbuild/llvm.rst | 44 +++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837