Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932336AbZJSVuj (ORCPT ); Mon, 19 Oct 2009 17:50:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932289AbZJSVui (ORCPT ); Mon, 19 Oct 2009 17:50:38 -0400 Received: from mga03.intel.com ([143.182.124.21]:12541 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932264AbZJSVui (ORCPT ); Mon, 19 Oct 2009 17:50:38 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,587,1249282800"; d="scan'208";a="200929012" Subject: Re: [RFC Patch] use MTRR for write combining if PAT is not available From: Suresh Siddha Reply-To: Suresh Siddha To: Ingo Molnar Cc: Thomas Schlichter , Jan Beulich , "arjan@linux.intel.com" , "dri-devel@lists.sourceforge.net" , "hancockrwd@gmail.com" , "hmh@hmh.eng.br" , "hpa@zytor.com" , "jbarnes@virtuousgeek.org" , "jeremy.fitzhardinge@citrix.com" , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , "tglx@linutronix.de" , "thellstrom@vmware.com" , "tj@kernel.org" , "Pallipadi, Venkatesh" , "x86@kernel.org" , "yinghai@kernel.org" In-Reply-To: <20091019153134.GA18198@elte.hu> References: <1392906098@web.de> <20091019153134.GA18198@elte.hu> Content-Type: text/plain Organization: Intel Corp Date: Mon, 19 Oct 2009 14:49:27 -0700 Message-Id: <1255988967.2576.36.camel@sbs-t61> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1165 Lines: 33 On Mon, 2009-10-19 at 08:31 -0700, Ingo Molnar wrote: > * Thomas Schlichter wrote: > > > I don't think this is a good idea, Robert Hancock wrote there may be > > millions of such Laptops (Core Solo/Duo erratum AE7, Pentium M erratum > > Y31) : > > > > http://marc.info/?l=linux-kernel&m=125537136105246&w=2 > > > > > or Perhaps just try to add mtrr only for the pci mmap case like the > > > 4th patch in this series.. > > > > I'd prefer this! ;-) > > Hm, we could perhaps do that - but i think we should only do that on > systems that have PAT disabled. > > Which brings up the question of how to properly QA such a narrow segment > of the market. Maybe disabling CONFIG_X86_PAT should enable that logic > too. Also, I think we can simplify and avoid mtrr_add_unaligned() and worry only about the pci mmap aligned cases etc. Those are the only interesting ones. thanks, suresh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/