Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751912Ab0DDHve (ORCPT ); Sun, 4 Apr 2010 03:51:34 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:52505 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751509Ab0DDHv2 (ORCPT ); Sun, 4 Apr 2010 03:51:28 -0400 To: Bernhard Walle Cc: Joerg Roedel , nhorman@redhat.com, nhorman@tuxdriver.com, Joerg Roedel , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Chris Wright , hbabu@us.ibm.com, iommu@lists.linux-foundation.org, vgoyal@redhat.com Subject: Re: [PATCH 3/4] Revert "x86: disable IOMMUs on kernel crash" References: <20100403012751.834020949@sous-sol.org> <20100403012820.229410717@sous-sol.org> <20100403174128.GQ24846@8bytes.org> <4BB83EAE.5090609@bwalle.de> From: ebiederm@xmission.com (Eric W. Biederman) Date: Sun, 04 Apr 2010 00:51:10 -0700 In-Reply-To: <4BB83EAE.5090609@bwalle.de> (Bernhard Walle's message of "Sun\, 04 Apr 2010 09\:24\:30 +0200") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: bernhard@bwalle.de, vgoyal@redhat.com, iommu@lists.linux-foundation.org, hbabu@us.ibm.com, chrisw@sous-sol.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, joerg.roedel@amd.com, nhorman@tuxdriver.com, nhorman@redhat.com, joro@8bytes.org X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Scanned: No (on in01.mta.xmission.com); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1124 Lines: 26 Bernhard Walle writes: > Am 03.04.10 19:49, schrieb Eric W. Biederman: >> Not a problem. We require a lot of things of the kdump kernel, >> and it is immediately apparent in a basic sanity test. > > Also, in most cases (for example: distribution kernels), the kdump > kernel nowadays is identical to the running kernel. So, if the running > kernel has IOMMU support, the kdump kernel also has. I have been rather pleasantly surprised at how well that works. Although I am still glad I insisted that using the same kernel version not be a hard requirement. It allowed us to specify a good solid interface. How to cope with GART in that situation without having to manually specify iommu=off in the configuration I find a more compelling question. I expect I will have a look at that in the coming months if someone doesn't get there before I do. 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/