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From: David Howells <dhowells@redhat.com>
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Subject: Re: [PATCH] Document Linux's memory barriers 
Date: Wed, 08 Mar 2006 12:34:25 +0000
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To: Linus Torvalds <torvalds@osdl.org>
Cc: Paul Mackerras <paulus@samba.org>, David Howells <dhowells@redhat.com>, akpm@osdl.org, mingo@redhat.com, linux-arch@vger.kernel.org, linuxppc64-dev@ozlabs.org, linux-kernel@vger.kernel.org
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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