Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758574AbYBSToO (ORCPT ); Tue, 19 Feb 2008 14:44:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752113AbYBSTn7 (ORCPT ); Tue, 19 Feb 2008 14:43:59 -0500 Received: from mga09.intel.com ([134.134.136.24]:44375 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752459AbYBSTn6 (ORCPT ); Tue, 19 Feb 2008 14:43:58 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.25,377,1199692800"; d="scan'208";a="299952765" Date: Tue, 19 Feb 2008 11:42:46 -0800 From: "Siddha, Suresh B" To: Roland Dreier Cc: Arjan van de Ven , Andi Kleen , Frans Pop , linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: Unable to continue testing of 2.6.25 Message-ID: <20080219194246.GA20438@linux-os.sc.intel.com> References: <200802171025.30590.elendil@planet.nl> <20080217124650.576990ce@laptopd505.fenrus.org> <20080218085018.05f3190a@laptopd505.fenrus.org> <20080218171159.GA24090@basil.nowhere.org> <20080218093215.5cf611a8@laptopd505.fenrus.org> <20080218110706.221d3015@laptopd505.fenrus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1101 Lines: 26 On Mon, Feb 18, 2008 at 11:18:48AM -0800, Roland Dreier wrote: > > > AFAIK mapping PCI memory WB is not allowed, so WC is really our only > > > choice. > > > afaik that depends on the BAR being prefetchable or not. > > In my case the BAR is prefetchable. Even if the BAR is prefetchable, on some platforms mapping MMIO space as WB can cause bad results like machine check etc. > > (and by your argument, ioremap_cached() would not be useful, and since that was, until > > 2.6.25-rc1, the default behavior for ioremap(), would have caused massive problems) > > I'm not sure what ioremap_cached() would really do in my case, since > the MTRRs for PCI memory are set to UC, so without monkeying with MTRR > contents (which can't really be done safely) the only choices we have > are leaving the mapping as UC or using PAT to get WC. 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/