From: Andi Kleen <ak@suse.de>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i386, x86_64 Initial PAT implementation
Date: Tue, 30 Aug 2005 16:50:22 +0200 [thread overview]
Message-ID: <200508301650.23149.ak@suse.de> (raw)
In-Reply-To: <1125413136.8276.14.camel@localhost.localdomain>
On Tuesday 30 August 2005 16:45, Alan Cox wrote:
> On Llu, 2005-08-29 at 18:20 -0600, Eric W. Biederman wrote:
> > ways. Currently this code only allows for an additional flavor
> > of uncached access to physical memory addresses which should be hard
> > to abuse, and should raise no additional aliasing problems. No
> > attempt has been made to fix theoretical aliasing problems.
>
> Even an uncached/cached alias causes random memory corruption or an MCE
> on x86 systems. In fact it can occur even for an alias not in theory
> touched by the CPU if it happens to prefetch into or speculate the
> address.
>
> Also be sure to read the PII Xeon errata - early PAT has a bug or two.
We can always force cpu_has_pat == 0 on these machines.
I don't think it is worth it to add any more complicated workarounds
for old broken systems.
-Andi
next prev parent reply other threads:[~2005-08-30 14:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-30 0:20 [PATCH] i386, x86_64 Initial PAT implementation Eric W. Biederman
[not found] ` <200508300230.39844.ak@suse.de>
2005-08-30 1:49 ` Eric W. Biederman
[not found] ` <200508300412.55027.ak@suse.de>
2005-08-30 6:21 ` solving page table access attribute aliasing Eric W. Biederman
[not found] ` <200508301714.35017.ak@suse.de>
2005-08-30 15:50 ` Eric W. Biederman
2005-08-30 14:45 ` [PATCH] i386, x86_64 Initial PAT implementation Alan Cox
2005-08-30 14:50 ` Andi Kleen [this message]
2005-08-30 15:31 ` Mikael Pettersson
2005-08-30 16:01 ` Eric W. Biederman
2005-08-30 15:20 ` Eric W. Biederman
[not found] ` <200508301748.50941.ak@suse.de>
2005-08-30 16:06 ` Eric W. Biederman
2005-08-30 17:06 ` Dave Jones
2005-08-31 1:39 ` Eric W. Biederman
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