Messages in this thread | | | From | Nick Desaulniers <> | Date | Wed, 29 Sep 2021 11:11:31 -0700 | Subject | Re: [PATCH 13/14] ARM: use .arch directives instead of assembler command line flags |
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On Tue, Sep 28, 2021 at 11:32 AM Arnd Bergmann <arnd@kernel.org> wrote: > > On Tue, Sep 28, 2021 at 7:10 PM Nick Desaulniers > <ndesaulniers@google.com> wrote: > > > > On Tue, Sep 28, 2021 at 8:42 AM Arnd Bergmann <arnd@kernel.org> wrote: > > > > > > From: Nick Desaulniers <ndesaulniers@google.com> > > > > > > Similar to commit a6c30873ee4a ("ARM: 8989/1: use .fpu assembler > > > directives instead of assembler arguments"). > > > > > > GCC and GNU binutils support setting the "sub arch" via -march=, > > > -Wa,-march, target function attribute, and .arch assembler directive. > > > > > > Clang's integrated assembler does not support -Wa,-march (and the logic > > > to overrule one when multiple of the above are used), and this can > > > cause annoying warnings such as: > > > > > > clang: warning: argument unused during compilation: '-march=armv6k' [-Wunused-command-line-argument] > > > clang: warning: argument unused during compilation: '-march=armv6k' [-Wunused-command-line-argument] > > > clang: warning: argument unused during compilation: '-march=armv6k' [-Wunused-command-line-argument] > > > > Note, the above lack of support was fixed in clang-13. That said, both > > Clang and GCC defer to -Wa,-march when -march is also present, so > > clang is still correct that -march is ignored. Thanks for resending; > > this is still helpful for earlier releases of clang that we still > > support. > > The -Wunused-command-line-argument warning also caused a build > failure for me when building with 'make W=1', and I think there are > cases where the flags from the command line are contradictory.
There's also -Werror now, which is hurting allmodconfig builds.
> Isn't the patch also needed for LTO? All I know is that with this > applied it all builds, but without it I run into link failures.
We don't support LTO on 32b ARM, yet. I would be interested in getting that support working.
> I can dig > more into the specific failures, but overall I think this is the right > thing to do anyway.
I agree. I was just adding additional context to the commit message via my initial reply. -- Thanks, ~Nick Desaulniers
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