Re: [PATCH v2 0/2] sparc/build: Rework CFLAGS for clang compatibility

[Nathan Chancellor <nathan@kernel.org>]

On Wed, Oct 23, 2024 at 04:10:01AM +0900, Masahiro Yamada wrote:
> I applied this patch set, but I still observe a build error.
...
> masahiro@zoe:~/workspace/linux-kbuild(kbuild)$ make
> LLVM=~/tools/llvm-latest/bin/  ARCH=sparc sparc64_defconfig all
...
> clang: error: unsupported argument '--undeclared-regs' to option '-Wa,'

Koakuma might know more than I do but I did not test either the
integrated assembler or the rest of the LLVM tools; I only tested clang
for CC. As far as I am aware, that has been where most of the effort in
llvm-project has been going and I think there are probably other fixes
that will be needed for the other tools. The command I tested was:

  $ make -skj"$(nproc)" \
         ARCH=sparc64 \
         CC=clang \
         CROSS_COMPILE=sparc64-linux-gnu- \
         LLVM_IAS=0 \
         mrproper defconfig all

I see this as more of a stepping stone series to make testing those
other components easier as time goes on, hence why I did not really
consider user facing documentation either like you brought up in the
other thread.

Cheers,
Nathan