Re: [PATCH] LoongArch: Specify -m32/-m64 explicitly for 32BIT/64BIT

From: WANG Rui

Date: Tue Apr 28 2026 - 04:03:55 EST

On Tue, Apr 28, 2026 at 3:07 PM Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote:
>
> Clang/LLVM build needs -m32/-m64 to switch triple variants (i.e. the
> --target=xxx parameter). Otherwise we get build errors for CONFIG_32BIT.
>
> GCC doesn't support -m32/-m64 now, but maybe support in future, so use
> cc-option to specify them.
>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202604232041.ESJDwVG4-lkp@xxxxxxxxx/
> Suggested-by: Nathan Chancellor <nathan@xxxxxxxxxx
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>

Tested-by: WANG Rui <wangrui@xxxxxxxxxxx>

Both Clang 18 building loongarch64 and Clang 22 building loongarch32
work as expected.

Cheers,
Rui

> ---
> arch/loongarch/Makefile | 2 ++
> arch/loongarch/vdso/Makefile | 2 ++
> 2 files changed, 4 insertions(+)
>
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index 47516aeea9d2..54fcfa1eac1f 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -55,9 +55,11 @@ endif
> ifdef CONFIG_32BIT
> tool-archpref = $(32bit-tool-archpref)
> UTS_MACHINE := loongarch32
> +cflags-y += $(call cc-option,-m32)
> else
> tool-archpref = $(64bit-tool-archpref)
> UTS_MACHINE := loongarch64
> +cflags-y += $(call cc-option,-m64)
> endif
>
> ifneq ($(SUBARCH),$(ARCH))
> diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile
> index 42aa96249828..9c9181bb4071 100644
> --- a/arch/loongarch/vdso/Makefile
> +++ b/arch/loongarch/vdso/Makefile
> @@ -12,6 +12,8 @@ obj-vdso-$(CONFIG_GENERIC_GETTIMEOFDAY) += vgettimeofday.o
> ccflags-vdso := \
> $(filter -I%,$(KBUILD_CFLAGS)) \
> $(filter -E%,$(KBUILD_CFLAGS)) \
> + $(filter -m32,$(KBUILD_CFLAGS)) \
> + $(filter -m64,$(KBUILD_CFLAGS)) \
> $(filter -march=%,$(KBUILD_CFLAGS)) \
> $(filter -m%-float,$(KBUILD_CFLAGS)) \
> $(CLANG_FLAGS) \
> --
> 2.52.0
>
>