Re: [PATCH] Document Linux's memory barriers

David Howells
2006-03-08T12:34:45Z

Linus Torvalds <torvalds@osdl.org> wrote:

> > Linus explained recently that wmb() on x86 does not order stores to
> > system memory w.r.t. stores to stores to prefetchable I/O memory (at
> > least that's what I think he said ;).

On i386 and x86_64, do IN and OUT instructions imply MFENCE? It's not obvious
from the x86_64 docs.

David