Re: [PATCH v3] Kbuild: do not emit debug info for assembly with LLVM_IAS=1

Nick Desaulniers
2020-11-16T23:41:55Z

Hi Masahiro, have you had time to review v3 of this patch?

On Mon, Nov 9, 2020 at 10:35 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> Clang's integrated assembler produces the warning for assembly files:
>
> warning: DWARF2 only supports one section per compilation unit
>
> If -Wa,-gdwarf-* is unspecified, then debug info is not emitted for
> assembly sources (it is still emitted for C sources). This will be
> re-enabled for newer DWARF versions in a follow up patch.
>
> Enables defconfig+CONFIG_DEBUG_INFO to build cleanly with
> LLVM=1 LLVM_IAS=1 for x86_64 and arm64.
>
> Cc: <stable@vger.kernel.org>
> Link: https://github.com/ClangBuiltLinux/linux/issues/716
> Reported-by: Dmitry Golovin <dima@golovin.in>
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Suggested-by: Dmitry Golovin <dima@golovin.in>
> Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
> Suggested-by: Sedat Dilek <sedat.dilek@gmail.com>
> Reviewed-by: Fangrui Song <maskray@google.com>
> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> Makefile | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index f353886dbf44..7e899d356902 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -826,7 +826,9 @@ else
> DEBUG_CFLAGS += -g
> endif
>
> +ifneq ($(LLVM_IAS),1)
> KBUILD_AFLAGS += -Wa,-gdwarf-2
> +endif
>
> ifdef CONFIG_DEBUG_INFO_DWARF4
> DEBUG_CFLAGS += -gdwarf-4
> --
> 2.29.2.222.g5d2a92d10f8-goog
>

--
Thanks,
~Nick Desaulniers