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    Subject[PATCH 3.11 166/208] x86, build: Pass in additional -mno-mmx, -mno-sse options
    Date
    3.11.10.2 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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: Luis Henriques <luis.henriques@canonical.com>
    ---
    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(-)

    diff --git a/arch/x86/Makefile b/arch/x86/Makefile
    index 39e5f1a..6218fcb 100644
    --- 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)
    diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
    index 379814b..6cf0111 100644
    --- 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

    diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
    index dcd90df..c8a6792 100644
    --- a/arch/x86/boot/compressed/Makefile
    +++ b/arch/x86/boot/compressed/Makefile
    @@ -13,6 +13,7 @@ KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
    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)

    diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
    index 8869287..9cac825 100644
    --- a/arch/x86/realmode/rm/Makefile
    +++ b/arch/x86/realmode/rm/Makefile
    @@ -73,9 +73,10 @@ KBUILD_CFLAGS := $(LINUXINCLUDE) -m32 -g -Os -D_SETUP -D__KERNEL__ -D_WAKEUP \
    -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__
    --
    1.8.3.2


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