Re: [PATCH] sparc/build: Make all compiler flags also clang-compatible

[John Paul Adrian Glaubitz]

Hi Nathan,

On Fri, 2024-06-21 at 11:53 -0700, Nathan Chancellor wrote:
> I think a good amount of the reasoning below the '---' could probably
> make it into the commit message as well but I don't have much of a
> vision there, maybe one of the SPARC folks will.
> 
> I saw through the LLVM issue above that one other patch is necessary to
> fix an issue in the vDSO [1], which I applied in testing this one. I
> noticed in applying that change that you appear to be working on 6.1,
> which is fine for now, but you'll need another diff once you get to a
> newer version, as we stopped using CROSS_COMPILE to set clang's
> '--target=' value:
> 
> diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang
> index 6c23c6af797f..2435efae67f5 100644
> --- a/scripts/Makefile.clang
> +++ b/scripts/Makefile.clang
> @@ -10,6 +10,7 @@ CLANG_TARGET_FLAGS_mips		:= mipsel-linux-gnu
>  CLANG_TARGET_FLAGS_powerpc	:= powerpc64le-linux-gnu
>  CLANG_TARGET_FLAGS_riscv	:= riscv64-linux-gnu
>  CLANG_TARGET_FLAGS_s390		:= s390x-linux-gnu
> +CLANG_TARGET_FLAGS_sparc	:= sparc64-linux-gnu
>  CLANG_TARGET_FLAGS_x86		:= x86_64-linux-gnu
>  CLANG_TARGET_FLAGS_um		:= $(CLANG_TARGET_FLAGS_$(SUBARCH))
>  CLANG_TARGET_FLAGS		:= $(CLANG_TARGET_FLAGS_$(SRCARCH))
> 
> With those, I can successfully build a kernel with clang that boots in
> QEMU :)
> 
>   $ make -skj"$(nproc)" \
>          ARCH=sparc64 \
>          CC=clang \
>          CROSS_COMPILE=sparc64-linux-gnu- \
>          LLVM_IAS=0 \
>          mrproper defconfig all
> 
>   $ qemu-system-sparc64 \
>         -serial mon:stdio \
>         -display none \
>         -no-reboot \
>         -M sun4u \
>         -cpu 'TI UltraSparc IIi' \
>         -m 512 \
>         -append console=ttyS0 \
>         -initrd sparc64-rootfs.cpio \
>         -kernel arch/sparc/boot/image
>   ...
>   [    1.788544] Run /init as init process
>   ...
>   Linux version 6.10.0-rc4+ (nathan@thelio-3990X) (ClangBuiltLinux clang version 19.0.0git (https://github.com/llvm/llvm-project a083e50f53f0f9eb9ad0c5b65f3c627cf97043e6), GNU ld (GNU Binutils) 2.42) #1 SMP Fri Jun 21 11:36:18 MST 2024
>   ...

Wow, this is really great progress. Kudos to everyone who helped to make this happen!

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
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