Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758299AbXFBIoQ (ORCPT ); Sat, 2 Jun 2007 04:44:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754786AbXFBIoD (ORCPT ); Sat, 2 Jun 2007 04:44:03 -0400 Received: from lucidpixels.com ([75.144.35.66]:53746 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753715AbXFBIoB (ORCPT ); Sat, 2 Jun 2007 04:44:01 -0400 Date: Sat, 2 Jun 2007 04:43:59 -0400 (EDT) From: Justin Piszcz X-X-Sender: jpiszcz@p34.internal.lan To: Jesse Barnes cc: Venki Pallipadi , Andi Kleen , 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? In-Reply-To: <200706011815.53065.jbarnes@virtuousgeek.org> Message-ID: References: <200706011441.57149.jbarnes@virtuousgeek.org> <20070602010539.GA13512@linux-os.sc.intel.com> <200706011815.53065.jbarnes@virtuousgeek.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1603 Lines: 37 On Fri, 1 Jun 2007, Jesse Barnes wrote: > On Friday, June 1, 2007 6:05:39 Venki Pallipadi wrote: >> 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=___". > > That might be best, short of actually fixing the MTRRs... > > Jesse > > Indeed, at least it will inform the user of -what- is going on. - 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/