From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH 2/2] x86/crash: Disable the watchdog NMIs on the crashing cpu. Date: Fri, 15 Nov 2013 21:01:09 +0000 Message-ID: <52868B95.6050004@citrix.com> References: <1384547567-17059-1-git-send-email-andrew.cooper3@citrix.com> <1384547567-17059-3-git-send-email-andrew.cooper3@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1384547567-17059-3-git-send-email-andrew.cooper3@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrew Cooper Cc: Tim Deegan , Keir Fraser , Jan Beulich , Xen-devel List-Id: xen-devel@lists.xenproject.org On 15/11/13 20:32, Andrew Cooper wrote: > PVOps Linux as a kexec image shoots itself in the foot otherwise. > > On a Core2 system, Linux declares a firmware bug and tries to invert some bits > in the performance counter register. It ends up setting the number of retired > instructions to generate another NMI to fewer instructions than the NMI > interrupt path itself, and ceases to make any useful progress. > > While this is not strictly Xen's fault, Xen can at least be kind and leave the > kexec environment with fewer issues to deal with. I don't appreciate my commit message being rewritten in this way. My original commit message was: "kexec: disable the NMI watchdog during a crash nmi_shootdown_cpus() is called during a crash to park all the other CPUs. This changes the NMI trap handlers which means there's no point in having the watchdog still running. This also disables the watchdog before executing any crash kexec image and prevents the image from receiving unexpected NMIs." David