tree 59c7aae8cab7c4e1e557dd3a4fff6afbffab38e2
parent 6628465e33ca694bd8fd5c3cf4eb7ff9177bc694
author Benjamin Herrenschmidt <benh@kernel.crashing.org> 1115098498 +1000
committer Linus Torvalds <torvalds@ppc970.osdl.org> 1115131114 -0700

[PATCH] ppc64: fix gcc 4.0 vs CONFIG_ALTIVEC

gcc-4.0 generates altivec code implicitly when -mcpu indicates an
altivec capable CPU which is not suitable for the kernel.  However, we
used to set -mcpu=970 when CONFIG_ALTIVEC was set because a gcc-3.x bug
prevented from using -maltivec along with -mcpu=power4, thus prevented
building the RAID6 altivec code.

This patch fixes all of this by testing for the gcc version.  If 4.0 or
later, just normally use -mcpu=power4 and let the RAID6 code add
-maltivec to the few files it needs to be compiled with altivec support.
For 3.x, we still use -mcpu=970 to work around the above problem, which
is fine as 3.x will never implicitly generate altivec code.

The Makefile hackery may not be the most lovely, I welcome anybody more
skilled than me to improve it.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>