Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755886AbXFWAOW (ORCPT ); Fri, 22 Jun 2007 20:14:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752422AbXFWAOO (ORCPT ); Fri, 22 Jun 2007 20:14:14 -0400 Received: from mx2.suse.de ([195.135.220.15]:53013 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752556AbXFWAON (ORCPT ); Fri, 22 Jun 2007 20:14:13 -0400 From: Andi Kleen Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) To: Alan Cox Subject: Re: [PATCH] x86-64: disable the GART before allocate aperture Date: Sat, 23 Jun 2007 02:14:01 +0200 User-Agent: KMail/1.9.6 Cc: "Eric W. Biederman" , Muli Ben-Yehuda , Yinghai Lu , Andrew Morton , Vivek Goyal , Linux Kernel Mailing List References: <200706221219.16243.yinghai.lu@sun.com> <20070622231951.4d516215@the-village.bc.nu> In-Reply-To: <20070622231951.4d516215@the-village.bc.nu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200706230214.02535.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1203 Lines: 28 On Saturday 23 June 2007 00:19:51 Alan Cox wrote: > > YH do you think you can look at simply reserving a portion of the iommu? > > And having the kexec on panic kernel use the reserved portion? > > How about simply reserving all of it for the base kernel and using soft > iommu for the panic kernel, its hardly high performance criticial at this > point. The kdump kernel should be normally all <4GB anyways. You won't need any IOMMU for its IO unless you O_DIRECT/sendfile out of /proc/kcore. Just don't do that (but I suspect it won't work anyways) If it's not then swiotlb will also not work because it won't get any memory <4GB. But I doubt this was YH's problem - the panic kernel memory is always reserved and there shouldn't be any ongoing DMAs in this area anyways. And what happens outside the kdump kernel shouldn't matter. I suspect he rather saw problems with non kdump kexec where we can just shut down the GART properly beforehand. -Andi - 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/