* tip-bot for H. Peter Anvin <tip...@zytor.com> wrote:
> Commit-ID: 5551a34e5aeab868f8d37f70d8754868921b4ee5
> Gitweb: http://git.kernel.org/tip/5551a34e5aeab868f8d37f70d8754868921b4ee5
> Author: H. Peter Anvin <h...@linux.intel.com>
> AuthorDate: Wed, 20 Nov 2013 13:31:49 -0800
> Committer: H. Peter Anvin <h...@linux.intel.com>
> CommitDate: Tue, 3 Dec 2013 17:40:22 -0800
>
> x86-64, build: Always pass in -mno-sse
>
> Always pass in the -mno-sse argument, regardless if
> -preferred-stack-boundary is supported. We never want to generate SSE
> instructions in the kernel unless we *really* know what we're doing.
>
> According to H. J. Lu, any version of gcc new enough that we support
> it at all should handle the -mno-sse option, so just add it
> unconditionally.
>
> Reported-by: Kevin B. Smith <kevin.b.sm...@intel.com>
> Signed-off-by: H. Peter Anvin <h...@linux.intel.com>
> Cc: H. J. Lu <hjl.to...@gmail.com>
> Link: http://lkml.kernel.org/n/tip-j21wzqv790q834n7yc6g8...@git.kernel.org
> Cc: <sta...@vger.kernel.org> # build fix only
> ---
> arch/x86/Makefile | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index 41250fb..eda00f9 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -31,6 +31,9 @@ ifeq ($(CONFIG_X86_32),y)
>
> KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
>
> + # Don't autogenerate SSE instructions
> + KBUILD_CFLAGS += -mno-sse
> +
> # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
> # with nonstandard options
> KBUILD_CFLAGS += -fno-pic
> @@ -57,8 +60,11 @@ else
> KBUILD_AFLAGS += -m64
> KBUILD_CFLAGS += -m64
>
> + # Don't autogenerate SSE instructions
> + KBUILD_CFLAGS += -mno-sse
> +
> # Use -mpreferred-stack-boundary=3 if supported.
> - KBUILD_CFLAGS += $(call cc-option,-mno-sse -mpreferred-stack-boundary=3)
> + KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=3)
>
> # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
> cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
Just a detail I noticed: in kbuild we intentionally use 8 spaces for
tabs in Makefiles and only use tabs for commands where tabs are
required.
The above code introduces tabs in the middle of 8-space sequences. It
works but is inconsistent.
Thanks,
Ingo
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