Per the discussion about half-way down in [1], the kernel doesn't actually support the ARMv3 ISA, but selects it for some ARMv4 ISA hardware that benefits from ARMv3 code generation. Such a consideration, then, only applies to the compiler but not to the assembler. This commit passes -march=armv4 to the assembler in those cases, so that code written for ARMv4 will continue to compile and run fine, without needing module-specific asflags-y overrides.
[1] https://lore.kernel.org/lkml/CAKv+Gu9FoFQymp2-=rueh14ckukon389oce7stycofwkzpa...@mail.gmail.com/ Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> --- I don't have too much familiarity with hardware this old, nor access to testing systems, so please do carefully evaluate the assertions above before merging this, since I'm not sure I have a full understanding of the Linux ARMv3 situation. arch/arm/Makefile | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/arm/Makefile b/arch/arm/Makefile index d1516f85f25d..7a264cacb482 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -76,8 +76,14 @@ arch-$(CONFIG_CPU_32v4T) =-D__LINUX_ARM_ARCH__=4 -march=armv4t arch-$(CONFIG_CPU_32v4) =-D__LINUX_ARM_ARCH__=4 -march=armv4 arch-$(CONFIG_CPU_32v3) =-D__LINUX_ARM_ARCH__=3 -march=armv3 +# We do not actually support the ARMv3 ISA and prefer it above only for +# code generation purposes, which does not apply to assembly. So we pass +# v4 to the assembler, so that we can still assemble all instructions. +arch-asflags-$(CONFIG_CPU_32v3) =-march=armv4 + # Evaluate arch cc-option calls now arch-y := $(arch-y) +arch-asflags-y := $(arch-asflags-y) # This selects how we optimise for the processor. tune-$(CONFIG_CPU_ARM7TDMI) =-mtune=arm7tdmi @@ -130,7 +136,7 @@ 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_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float +KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) $(arch-asflags-y) -include asm/unified.h -msoft-float CHECKFLAGS += -D__arm__ -- 2.19.0
