Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755024AbXFVU2d (ORCPT ); Fri, 22 Jun 2007 16:28:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751348AbXFVU21 (ORCPT ); Fri, 22 Jun 2007 16:28:27 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:53172 "EHLO the-village.bc.nu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751099AbXFVU20 (ORCPT ); Fri, 22 Jun 2007 16:28:26 -0400 Date: Fri, 22 Jun 2007 21:33:27 +0100 From: Alan Cox To: Muli Ben-Yehuda Cc: Yinghai Lu , Andi Kleen , Andrew Morton , "Eric W. Biederman" , Vivek Goyal , Linux Kernel Mailing List Subject: Re: [PATCH] x86-64: disable the GART before allocate aperture Message-ID: <20070622213327.69663288@the-village.bc.nu> In-Reply-To: <20070622193124.GG5051@rhun.smartcity.com> References: <200706221219.16243.yinghai.lu@sun.com> <20070622193124.GG5051@rhun.smartcity.com> X-Mailer: Claws Mail 2.9.1 (GTK+ 2.10.8; i386-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1223 Lines: 27 On Fri, 22 Jun 2007 12:31:24 -0700 Muli Ben-Yehuda wrote: > On Fri, Jun 22, 2007 at 12:19:15PM -0700, Yinghai Lu wrote: > > [PATCH] x86-64: disable the GART before allocate aperture > > > > For K8 system: 4G RAM with memory hole remapping enabled, or more > > than 4G RAM installed. when mem is allocated for GART, it will do > > the memset for clear. and for kexec case, the first kernel already > > enable that, the memset in second kernel will cause the system > > restart. So disable that at first before we try to allocate mem for > > it. > > Why does the memset in the second kernel cause a system restart? You've got mapped live gart pages from the previous kernel. Even if you disable the gart before a memset you may well have the video card using gart translations and possibly live IOMMU mappings for devices using it via bus mastering - and those will cause you MCE exceptions with a corrupt cpu context flag (ie not nicely recoverable). Alan - 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/