From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: linux@armlinux.org.uk, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, arm@kernel.org
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: [PATCH] ARM: makefile: pass -march=armv4 to assembler even on CPU32v3
Date: Sun, 30 Sep 2018 04:49:04 +0200 [thread overview]
Message-ID: <20180930024904.14240-1-Jason@zx2c4.com> (raw)
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-=rUeh14CkUKON389OCE7stYCOFwKZpaCrg@mail.gmail.com/
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Ard Biesheuvel <ard.biesheuvel@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
next reply other threads:[~2018-09-30 2:49 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-30 2:49 Jason A. Donenfeld [this message]
2018-10-01 15:13 ` [PATCH] ARM: makefile: pass -march=armv4 to assembler even on CPU32v3 Arnd Bergmann
2018-10-02 3:53 ` Jason A. Donenfeld
2018-10-02 5:39 ` Ard Biesheuvel
2018-10-02 7:51 ` Arnd Bergmann
2018-10-02 9:16 ` Ard Biesheuvel
2018-10-02 12:30 ` Jason A. Donenfeld
2018-10-02 13:10 ` Ard Biesheuvel
2018-10-02 13:12 ` Jason A. Donenfeld
2018-10-02 13:20 ` [PATCH] ARM: makefile: use ARMv3M mode for RiscPC Jason A. Donenfeld
2018-10-02 13:28 ` Ard Biesheuvel
2018-10-02 13:53 ` Arnd Bergmann
2018-10-02 14:02 ` Jason A. Donenfeld
2018-10-01 17:56 ` [PATCH] ARM: makefile: pass -march=armv4 to assembler even on CPU32v3 Russell King - ARM Linux
2018-10-01 18:10 ` Ard Biesheuvel
2018-10-01 18:13 ` Russell King - ARM Linux
2018-10-02 3:56 ` Jason A. Donenfeld
2018-10-02 4:08 ` Jason A. Donenfeld
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