[PATCH] x86_64: Prevent gcc from generating MMX code by mistake.

This will help only on gcc 4+.  On older gccs there is a workaround too, but
it is so ugly and there are no actual observed failures that I didn't apply
it.
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: <rth@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/Makefile

@@ -59,6 +59,8 @@ endif
 # -funit-at-a-time shrinks the kernel .text considerably
 # unfortunately it makes reading oopses harder.
 CFLAGS += $(call cc-option,-funit-at-a-time)
+# prevent gcc from generating any FP code by mistake
+CFLAGS += $(call cc-option,-mno-sse -mno-mmx -mno-sse2 -mno-3dnow,)
 
 head-y := arch/x86_64/kernel/head.o arch/x86_64/kernel/head64.o arch/x86_64/kernel/init_task.o