Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763096AbXFBBJS (ORCPT ); Fri, 1 Jun 2007 21:09:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757090AbXFBBJJ (ORCPT ); Fri, 1 Jun 2007 21:09:09 -0400 Received: from mga01.intel.com ([192.55.52.88]:18551 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752902AbXFBBJI (ORCPT ); Fri, 1 Jun 2007 21:09:08 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.16,374,1175497200"; d="scan'208";a="252349575" Date: Fri, 1 Jun 2007 18:05:39 -0700 From: Venki Pallipadi To: Jesse Barnes Cc: Andi Kleen , Justin Piszcz , linux-kernel@vger.kernel.org Subject: Re: Intel's response Linux/MTRR/8GB Memory Support / Why doesn't the kernel realize the BIOS has problems and re-map appropriately? Message-ID: <20070602010539.GA13512@linux-os.sc.intel.com> References: <200706011407.51779.jbarnes@virtuousgeek.org> <20070601211943.GO7217@one.firstfloor.org> <200706011441.57149.jbarnes@virtuousgeek.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200706011441.57149.jbarnes@virtuousgeek.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1340 Lines: 26 On Fri, Jun 01, 2007 at 02:41:57PM -0700, Jesse Barnes wrote: > On Friday, June 1, 2007 2:19:43 Andi Kleen wrote: > > And normally the MTRRs win, don't they (if I remember the table correctly) > > So if the MTRR says UC and PAT disagrees it might not actually help > > I just checked, yes the MTRRs win for UC types. But it sounds like the cases > we're talking about are actually situations where there's no MTRR coverage, > so the default type is used. The manual doesn't specifically call out how > memory using the default type interacts with PAT, but it may well be that it > stays uncached if the default type is uncached. Again that argues for fixing > the MTRR mapping problem in some way. > I feel, having a silent/transparent workaround is not a good idea. With that chances are BIOS bug will go unnoticed (having an error message in dmesg may not get noticed either). Probably we should just panic at boot with a detailed message about the e820 mtrr discrepancy (which can be logged as a BUG to BIOS provider) and suggest a temporary workaround of "mem=___". Thanks, Venki - 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/