[PATCH 3.12 069/118] x86, build: Pass in additional -mno-mmx, -mno-sse options

Greg Kroah-Hartman
2013-12-18T21:30:44Z

From: "H. Peter Anvin" <hpa@linux.intel.com>

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@intel.com>
Cc: Sunil K. Pandey <sunil.k.pandey@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: H. J. Lu <hjl.tools@gmail.com>
Link: http://lkml.kernel.org/n/tip-j21wzqv790q834n7yc6g80j1@git.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/Makefile | 8 ++++----
arch/x86/boot/Makefile | 6 +++---
arch/x86/boot/compressed/Makefile | 1 +
arch/x86/realmode/rm/Makefile | 3 ++-
4 files changed, 10 insertions(+), 8 deletions(-)

--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -31,8 +31,8 @@ ifeq ($(CONFIG_X86_32),y)

KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return

- # Don't autogenerate SSE instructions
- KBUILD_CFLAGS += -mno-sse
+ # Don't autogenerate MMX or SSE instructions
+ KBUILD_CFLAGS += -mno-mmx -mno-sse

# Never want PIC in a 32-bit kernel, prevent breakage with GCC built
# with nonstandard options
@@ -60,8 +60,8 @@ else
KBUILD_AFLAGS += -m64
KBUILD_CFLAGS += -m64

- # Don't autogenerate SSE instructions
- KBUILD_CFLAGS += -mno-sse
+ # Don't autogenerate MMX or SSE instructions
+ KBUILD_CFLAGS += -mno-mmx -mno-sse

# Use -mpreferred-stack-boundary=3 if supported.
KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=3)
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -53,18 +53,18 @@ $(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.
-KBUILD_CFLAGS := $(USERINCLUDE) -g -Os -D_SETUP -D__KERNEL__ \
+KBUILD_CFLAGS := $(USERINCLUDE) -m32 -g -Os -D_SETUP -D__KERNEL__ \
-DDISABLE_BRANCH_PROFILING \
-Wall -Wstrict-prototypes \
-march=i386 -mregparm=3 \
-include $(srctree)/$(src)/code16gcc.h \
-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
+ -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)
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
GCOV_PROFILE := n

--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -13,6 +13,7 @@ KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFIL
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)

--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -73,9 +73,10 @@ KBUILD_CFLAGS := $(LINUXINCLUDE) -m32 -g
-march=i386 -mregparm=3 \
-include $(srctree)/$(src)/../../boot/code16gcc.h \
-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
+ -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_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__