From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Andi Kleen <ak@suse.de>
Subject: Re: [PATCH] Document Linux's memory barriers
Date: Tue, 7 Mar 2006 12:01:21 -0800
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Cc: "Bryan O'Sullivan" <bos@serpentine.com>,
       David Howells <dhowells@redhat.com>, torvalds@osdl.org, akpm@osdl.org,
       mingo@redhat.com, linux-arch@vger.kernel.org, linuxppc64-dev@ozlabs.org,
       linux-kernel@vger.kernel.org
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On Tuesday, March 7, 2006 3:57 am, Andi Kleen wrote:
> On Tuesday 07 March 2006 20:23, Bryan O'Sullivan wrote:
> > On Tue, 2006-03-07 at 18:30 +0000, David Howells wrote:
> > > True, I suppose. I should make it clear that these accessor
> > > functions imply memory barriers, if indeed they do,
> >
> > They don't, but according to Documentation/DocBook/deviceiobook.tmpl
> > they are performed by the compiler in the order specified.
>
> I don't think that's correct. Probably the documentation should
> be fixed.

On ia64 I'm pretty sure it's true, and it seems like it should be in the 
general case too.  The compiler shouldn't reorder uncached memory 
accesses with volatile semantics...

Jesse
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