Date: Sun, 13 Nov 2005 11:36:42 -0800 (PST)
From: Linus Torvalds <torvalds@osdl.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
cc: Andi Kleen <ak@suse.de>, Dave Jones <davej@redhat.com>,
       Zachary Amsden <zach@vmware.com>, Pavel Machek <pavel@ucw.cz>,
       Andrew Morton <akpm@osdl.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       "H. Peter Anvin" <hpa@zytor.com>,
       Zwane Mwaikambo <zwane@arm.linux.org.uk>,
       Pratap Subrahmanyam <pratap@vmware.com>,
       Christopher Li <chrisl@vmware.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>,
       Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 1/10] Cr4 is valid on some 486s
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On Sun, 13 Nov 2005, Alan Cox wrote:
>
> On Sul, 2005-11-13 at 20:00 +0100, Andi Kleen wrote:
> > It's a bad hack anyways. Better would be probably to use a uncached WC write.
> > I would rather use that.
> 
> I'm not clear that anything but lock operations have the required
> guarantee of atomicity relative to bus masters which are not processors.
> Especially so on intel.

The thing is, we wouldn't ever remove _all_ lock prefixes. Only the ones 
that already depend on SMP.

So the memory barriers etc that have lock prefixes even on UP would be 
totally untouched.

		Linus
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