From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756340Ab3J1MEH (ORCPT ); Mon, 28 Oct 2013 08:04:07 -0400 Received: from mout.gmx.net ([212.227.17.21]:54372 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755683Ab3J1MEE convert rfc822-to-8bit (ORCPT ); Mon, 28 Oct 2013 08:04:04 -0400 Date: Mon, 28 Oct 2013 13:03:58 +0100 From: Andreas Werner To: Borislav Petkov Cc: Ingo Molnar , tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] X86: MM: Add PAT Type write-through in combination with mtrr Message-ID: <20131028120358.GE2278@thinkpad.fritz.box> References: <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> <20131028103428.GA2278@thinkpad.fritz.box> <20131028105731.GF4314@pd.tnic> <20131028112505.GD2278@thinkpad.fritz.box> <20131028114541.GI4314@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20131028114541.GI4314@pd.tnic> User-Agent: Mutt/1.5.21 (2010-09-15) Content-Transfer-Encoding: 8BIT X-Provags-ID: V03:K0:2JPYFRau6YqDLk3PbDNcAPWRHUVKYRApnETuPD0vf247cUtvf4L nOszWhv0pf6vypW6R4xm/YJ8/CBlJ44j8RRdtCESZB+zycvwZoehAqr5amjB/o9eFi+AP9W XW/LuDpXwsoeXLVT3PH4ocDbaX3+nMjnl4yeOaIupCUXy6NyZBgVGNtnai3ecOihlgE9iXR ZhpUYDDhMBzmXcPBZhcrA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 28, 2013 at 12:45:41PM +0100, Borislav Petkov wrote: > Drop Dave's stale mail address. > > On Mon, Oct 28, 2013 at 12:25:05PM +0100, Andreas Werner wrote: > > > but you end up doing > > > > > > PAT=Write-Back + MTRR=Write-Through = Effective Memory of Write-Back > > > > > No the effective memory type is WT, check out the Intel document with the > > table of Effective memory type combinations. > > You need to read what I'm saying more carefully. Sorry then i missunderstood something? > > > Yes but, there is no way in the kernel to mark a memory WT, > > That doesn't mean you can return _PAGE_CACHE_WB for MTRR_TYPE_WRTHROUGH. > The correct thing to do, IMHO, would be to set the PWT bit in the PTEs > of those pages comprising your buffer. > But why? the combination of PAT=WB and MTRR=WT is allowed isnīt it? What should i return instead of? regards Andy > -- > Regards/Gruss, > Boris. > > Sent from a fat crate under my desk. Formatting is fine. > --