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SubjectRe: [PATCH] ARM: pass -msoft-float to gcc earlier
On Tue, May 19, 2020 at 3:09 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> Szabolcs Nagy ran into a kernel build failure with a custom gcc
> toochain that sets -mfpu=auto -mfloat-abi=hard:
>
> /tmp/ccmNdcdf.s:1898: Error: selected processor does not support `cpsid i' in ARM mode
>
> The problem is that $(call cc-option, -march=armv7-a) fails before the
> kernel overrides the gcc options to also pass -msoft-float.

The call to `$(call cc-option, -march=armv7-a)

>
> Move the option to the beginning the Makefile, before we call

beginning of the

> cc-option for the first time.
>
> Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87302
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Moving this looks harmless enough, though it's not clear to me how the
failure you're describing would occur. I don't see calls to as-instr
in arch/arm/Makefile. Which object is being built before -msoft-float
is being set?

> ---
> arch/arm/Makefile | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
> index 7d5cd0f85461..e428ea6eb0fa 100644
> --- a/arch/arm/Makefile
> +++ b/arch/arm/Makefile
> @@ -16,6 +16,8 @@ LDFLAGS_vmlinux += --be8
> KBUILD_LDFLAGS_MODULE += --be8
> endif
>
> +KBUILD_CFLAGS += -msoft-float
> +
> ifeq ($(CONFIG_ARM_MODULE_PLTS),y)
> KBUILD_LDS_MODULE += $(srctree)/arch/arm/kernel/module.lds
> endif
> @@ -135,7 +137,7 @@ AFLAGS_ISA :=$(CFLAGS_ISA)
> endif
>
> # Need -Uarm for gcc < 3.x
> -KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm
> +KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -Uarm
> KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float
>
> CHECKFLAGS += -D__arm__
> --
> 2.26.2
>


--
Thanks,
~Nick Desaulniers

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