From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932192AbVH3QGh (ORCPT ); Tue, 30 Aug 2005 12:06:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932193AbVH3QGh (ORCPT ); Tue, 30 Aug 2005 12:06:37 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:29090 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S932192AbVH3QGg (ORCPT ); Tue, 30 Aug 2005 12:06:36 -0400 To: Andi Kleen Cc: Alan Cox , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] i386, x86_64 Initial PAT implementation References: <1125413136.8276.14.camel@localhost.localdomain> <200508301748.50941.ak@suse.de> From: ebiederm@xmission.com (Eric W. Biederman) Date: Tue, 30 Aug 2005 10:06:07 -0600 In-Reply-To: <200508301748.50941.ak@suse.de> (Andi Kleen's message of "Tue, 30 Aug 2005 17:48:50 +0200") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen writes: > On Tuesday 30 August 2005 17:20, Eric W. Biederman wrote: > >> Right. To the best of my understanding problem aliases are either >> uncached/write-back or write-combine/write-back. I don't think >> uncached/write-combine can cause problems. My basic reason for > > Well it can if one driver expects the mapping to be uncached and the > other to be WC. The WC one might blast over the other one badly. > > Also the architecture defines all attribute conflicts to be undefined > and it's better to not rely on undefined behaviour because that could > break quite badly on a future microarchitecture. Agreed. It is better. My assessment was only to show that the immediate danger of data corruption or problems isn't very high, even if someone does goof. Eric