Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759900AbXFVVmA (ORCPT ); Fri, 22 Jun 2007 17:42:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753013AbXFVVlx (ORCPT ); Fri, 22 Jun 2007 17:41:53 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:43472 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753983AbXFVVlw (ORCPT ); Fri, 22 Jun 2007 17:41:52 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Andi Kleen Cc: Alan Cox , Muli Ben-Yehuda , Yinghai Lu , Andrew Morton , Vivek Goyal , Linux Kernel Mailing List Subject: Re: [PATCH] x86-64: disable the GART before allocate aperture References: <200706221219.16243.yinghai.lu@sun.com> <20070622193124.GG5051@rhun.smartcity.com> <20070622213327.69663288@the-village.bc.nu> <200706222328.21259.ak@suse.de> Date: Fri, 22 Jun 2007 15:41:24 -0600 In-Reply-To: <200706222328.21259.ak@suse.de> (Andi Kleen's message of "Fri, 22 Jun 2007 23:28:20 +0200") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1506 Lines: 34 Andi Kleen writes: > On Friday 22 June 2007 22:33, Alan Cox wrote: >> You've got mapped live gart pages from the previous kernel. Even if you >> disable the gart before a memset > > It's probably too late then. It could also interfere with other operations. > If anything the GART should be disabled during kexec shutdown. Perhaps we just > need a suitable suspend function that does that. Eric, any preferences? Well it would be a shutdown method not a suspend method. The authors of the suspend code thought sharing code with the reboot and the rmmod case didn't make sense. For a normal kexec into another kernel I think this makes sense. >> 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). > > We disable those machine checks on K8 because they're not fully reliable. For the kexec on panic not shutting the hardware down if at all possible is the ideal. There I think we need a mode to not touch a chunk of the iommu and reserve it for the kexec on panic kernel (or perhaps just use the swiotlb code if we need bounce buffers at all). Eric - 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/