[PATCH 3.2 129/185] x86, build: Pass in additional -mno-mmx,-mno-sse options

From: Ben Hutchings
Date: Sat Dec 28 2013 - 21:36:41 EST

3.2.54-rc1 review patch. If anyone has any objections, please let me know.


From: "H. Peter Anvin" <hpa@xxxxxxxxxxxxxxx>

commit 8b3b005d675726e38bc504d2e35a991e55819155 upstream.

In checkin

5551a34e5aea x86-64, build: Always pass in -mno-sse

we unconditionally added -mno-sse to the main build, to keep newer
compilers from generating SSE instructions from autovectorization.
However, this did not extend to the special environments
(arch/x86/boot, arch/x86/boot/compressed, and arch/x86/realmode/rm).
Add -mno-sse to the compiler command line for these environments, and
add -mno-mmx to all the environments as well, as we don't want a
compiler to generate MMX code either.

This patch also removes a $(cc-option) call for -m32, since we have
long since stopped supporting compilers too old for the -m32 option,
and in fact hardcode it in other places in the Makefiles.

Reported-by: Kevin B. Smith <kevin.b.smith@xxxxxxxxx>
Cc: Sunil K. Pandey <sunil.k.pandey@xxxxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: H. J. Lu <hjl.tools@xxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-j21wzqv790q834n7yc6g80j1@xxxxxxxxxxxxxx
[bwh: Backported to 3.2:
- Drop changes to arch/x86/Makefile, which sets these flags earlier
- Adjust context
- Drop changes to arch/x86/realmode/rm/Makefile which doesn't exist]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -51,18 +51,18 @@ $(obj)/cpustr.h: $(obj)/mkcpustr FORCE

# How to compile the 16-bit code. Note we always compile for -march=i386,
# that way we can complain to the user if the CPU is insufficient.
-Wall -Wstrict-prototypes \
-march=i386 -mregparm=3 \
-include $(srctree)/$(src)/code16gcc.h \
-fno-strict-aliasing -fomit-frame-pointer \
+ -mno-mmx -mno-sse \
$(call cc-option, -ffreestanding) \
$(call cc-option, -fno-toplevel-reorder,\
- $(call cc-option, -fno-unit-at-a-time)) \
+ $(call cc-option, -fno-unit-at-a-time)) \
$(call cc-option, -fno-stack-protector) \
$(call cc-option, -mpreferred-stack-boundary=2)
-KBUILD_CFLAGS += $(call cc-option, -m32)

--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
cflags-$(CONFIG_X86_32) := -march=i386
cflags-$(CONFIG_X86_64) := -mcmodel=small
KBUILD_CFLAGS += $(cflags-y)
+KBUILD_CFLAGS += -mno-mmx -mno-sse
KBUILD_CFLAGS += $(call cc-option,-ffreestanding)
KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)

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