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[POWERPC] Add -mno-spe for ARCH=powerpc builds

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Newer GCC's are capable of autovectorization for ISA extensions like
AltiVec and SPE.  If we happen to build with one of those compilers we
will get SPE instructions in random kernel code.  Today we only allow
basic interger code in the kernel and FP, AltiVec, or SPE in special
explicit locations that have handled the proper saving and restoring of
the register state (since on uniprocessor we lazy context switch the
register state for FP, AltiVec, and SPE).

-mno-spe disables the compiler for automatically generating SPE
instructions without our knowledge.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
This commit is contained in:
Kumar Gala 2007-10-18 16:53:19 -05:00
parent 688016f4e2
commit 0197cd2e35
1 changed files with 3 additions and 0 deletions
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3
arch/powerpc/Makefile
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@ -107,6 +107,9 @@ endif
# No AltiVec instruction when building kernel
KBUILD_CFLAGS += $(call cc-option,-mno-altivec)
# No SPE instruction when building kernel
KBUILD_CFLAGS += $(call cc-option,-mno-spe)
# Enable unit-at-a-time mode when possible. It shrinks the
# kernel considerably.
KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)