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SubjectRe: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code
FromBenjamin Herrenschmidt <>
DateTue, 20 May 2008 18:02:18 -0400

On Tue, 2008-05-20 at 16:38 -0500, Scott Wood wrote:
> It looks like we rely on -fno-strict-aliasing to prevent reordering
> ordinary memory accesses (such as to DMA descriptors) past the I/O
> access. It won't prevent reordering of memory reads around an I/O
> read,
> though, which could be a problem if the I/O read result determines
> the
> validity of the DMA buffer. IMHO, a memory clobber would be better.

We probably want a full "memory" clobber then...

Ben.




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