ARM: pass -marm to gcc by default for both C and assembler (91802a8e) · Commits · 戴 / test

The Linaro cross toolchain and probably others nowadays default to building in THUMB2 mode. When building a kernel for a CPU that does not support THUMB2, the compiler complains about incorrect flags. We can work around this by setting -marm for all non-T2 builds. -marm was passed unconditionally for C files previously, but nothing was passed to the gcc frontend when processing .S files, resulting in a warning. The assembler never defaults to ARM unless -Wa,-mthumb is supplied explicitly, so the files were still assembled correctly. This patch makes sure that -marm is passed for .S files too, and also avoids the redundant gcc -marm -mthumb in Thumb kernels. Without this patch, building assabet_defconfig results in: usr/initramfs_data.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default] arch/arm/nwfpe/entry.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default] firmware/cis/PCMLM28.cis.gen.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default] (and many more) Signed-off-by:

Arnd Bergmann <arnd@arndb.de> Acked-by:

Nicolas Pitre <nico@linaro.org> Acked-by:

Dave Martin <dave.martin@linaro.org> Cc: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Makefile

+7 −6

Original line number	Diff line number	Diff line
		@@ -21,8 +21,6 @@ endif
		OBJCOPYFLAGS :=-O binary -R .comment -S
		GZFLAGS :=-9
		#KBUILD_CFLAGS +=-pipe
		# Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
		KBUILD_CFLAGS +=$(call cc-option,-marm,)

		# Never generate .eh_frame
		KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm)
		@@ -105,17 +103,20 @@ endif
		ifeq ($(CONFIG_THUMB2_KERNEL),y)
		AFLAGS_AUTOIT :=$(call as-option,-Wa$(comma)-mimplicit-it=always,-Wa$(comma)-mauto-it)
		AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W)
		CFLAGS_THUMB2 :=-mthumb $(AFLAGS_AUTOIT) $(AFLAGS_NOWARN)
		AFLAGS_THUMB2 :=$(CFLAGS_THUMB2) -Wa$(comma)-mthumb
		CFLAGS_ISA :=-mthumb $(AFLAGS_AUTOIT) $(AFLAGS_NOWARN)
		AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb
		# Work around buggy relocation from gas if requested:
		ifeq ($(CONFIG_THUMB2_AVOID_R_ARM_THM_JUMP11),y)
		CFLAGS_MODULE +=-fno-optimize-sibling-calls
		endif
		else
		CFLAGS_ISA :=$(call cc-option,-marm,)
		AFLAGS_ISA :=$(CFLAGS_ISA)
		endif

		# Need -Uarm for gcc < 3.x
		KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_THUMB2) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm
		KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_THUMB2) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float
		KBUILD_CFLAGS +=$(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

		CHECKFLAGS += -D__arm__

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