From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Egger Subject: breakage with c/s 19950 Date: Tue, 21 Jul 2009 16:49:16 +0200 Message-ID: <200907211649.16613.Christoph.Egger@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org Hi Jan! In c/s 19950, you disable the GART TLB walk error of the northbridge as a workaround for AMD K8 CPUs. The comment says, it happens with IOMMU & 3ware & Cerberus. There's a Linux/Dom0 boot problem with this: The Linux/Dom0 kernel also has this workaround which leads to a #GP in the guest because in Xen mce.c:mce_wrmsr() returns -1. The question is, is the workaround really really necessary ? IOMMU is not yet on market and if there will be AMD K8 machines with an IOMMU is very questionable. If the workaround is not needed, please remove it from both Linux and Xen. If the workaround is valid, then mce.c:mce_wrmsr() needs a special check for this workaround to NOT return -1. Christoph -- ---to satisfy European Law for business letters: Advanced Micro Devices GmbH Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen Geschaeftsfuehrer: Thomas M. McCoy, Giuliano Meroni Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632