From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932214AbVH3RHG (ORCPT ); Tue, 30 Aug 2005 13:07:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932225AbVH3RHF (ORCPT ); Tue, 30 Aug 2005 13:07:05 -0400 Received: from mx1.redhat.com ([66.187.233.31]:31941 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S932214AbVH3RHE (ORCPT ); Tue, 30 Aug 2005 13:07:04 -0400 Date: Tue, 30 Aug 2005 13:06:00 -0400 From: Dave Jones To: Alan Cox Cc: "Eric W. Biederman" , Andrew Morton , linux-kernel@vger.kernel.org, Andi Kleen Subject: Re: [PATCH] i386, x86_64 Initial PAT implementation Message-ID: <20050830170600.GA10042@redhat.com> Mail-Followup-To: Dave Jones , Alan Cox , "Eric W. Biederman" , Andrew Morton , linux-kernel@vger.kernel.org, Andi Kleen References: <1125413136.8276.14.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1125413136.8276.14.camel@localhost.localdomain> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 30, 2005 at 03:45:36PM +0100, 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. There are various PAT errata all the way through to Pentium-M iirc. Dave