From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756090Ab3J1K4t (ORCPT ); Mon, 28 Oct 2013 06:56:49 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57110 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754133Ab3J1K4s (ORCPT ); Mon, 28 Oct 2013 06:56:48 -0400 Message-ID: <526E421A.3090507@zytor.com> Date: Mon, 28 Oct 2013 03:53:14 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Ingo Molnar , Andreas Werner CC: Borislav Petkov , tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, dave@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] X86: MM: Add PAT Type write-through in combination with mtrr References: <20131027133401.GB24817@pd.tnic> <20131027165159.GD1617@thinkpad.fritz.box> <20131027173131.GC21868@pd.tnic> <20131027175608.GA1340@thinkpad.fritz.box> <20131027190148.GD21868@pd.tnic> <20131028062946.GA1391@thinkpad.fritz.box> <20131028101749.GA4389@gmail.com> <20131028102938.GD4314@pd.tnic> <20131028103132.GA6274@gmail.com> <20131028104505.GB2278@thinkpad.fritz.box> <20131028105101.GC6274@gmail.com> In-Reply-To: <20131028105101.GC6274@gmail.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/28/2013 03:51 AM, Ingo Molnar wrote: >> >> If i mark the region WB and call clflush my system will crash without >> any message, it just stop working. > > Yeah, I was wondering whether it's valid at all to mark IO memory as > cacheable - with the lack of MESI transactions and all that ... > > So it's apparently not valid and we've got to live with WT as the > 'best' caching/bursting method for reads. > On a lot of systems I'm not sure if even WT is legitimate. -hpa