On Fri, 2007-03-23 at 13:56 +0100, Segher Boessenkool wrote:

quoted

GCC may generate inline copy loop to handle memcpy() function
instead of kernel defined memcpy() with -mstring or -Os.
But this inlined version of memcpy() caused an alignment interrupt
when copying from SPU local store on PS3.
(http://ozlabs.org/pipermail/cbe-oss-dev/2007-March/001348.html)

This patch deletes -mstring option on all powerpc and force -mno-string
option on Cell.

Please split into two patches, the first half (deleting
-mstring) we can all agree on and "the other half".

What your patch does is setting -mno-string for all files
if your kernel is configured to support Cell.  It would be
better to set this option (and all other options needed,
-mno-multiple and -mno-algebraic come to mind, and that last
compiler option doesn't even exist yet) unconditionally on
the few Cell-specific files that are affected, not on the
whole kernel:

	CFLAGS_whatever.o := -msome-flags

It would be even better to not lie to the compiler by
telling it it can use the LS area as normal memory, since
evidently it cannot :-)

It's fair enough to use -mno-string overall. If the kernel is going to
run on cell, performance will suck with string instructions. In fact,
I'm not sure they are worth having on anything anyway.

Ben.