From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 0/2] Introduce panic hypercall Date: Mon, 20 Jun 2011 20:23:20 +0300 Message-ID: <4DFF8208.7060401@redhat.com> References: <1308577094-17551-1-git-send-email-gollub@b1-systems.de> <20110620153825.GH13042@redhat.com> <4DFF6B20.7090107@redhat.com> <201106201826.32975.gollub@b1-systems.de> <4DFF76B1.8020509@redhat.com> <4DFF7FD0.4070002@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Daniel Gollub , "Daniel P. Berrange" , kvm@vger.kernel.org, qemu-devel To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34073 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755353Ab1FTRX3 (ORCPT ); Mon, 20 Jun 2011 13:23:29 -0400 In-Reply-To: <4DFF7FD0.4070002@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/20/2011 08:13 PM, Jan Kiszka wrote: > > A watchdog has the advantage that is also detects lockups. > > > > In fact you could implement the panic device via the existing > > watchdogs. Simply program the timer for the minimum interval and > > *don't* service the interrupt. This would work for non-virt setups as > > well as another way to issue a reset. > > If you manage to bring down the other guest CPUs fast enough. Otherwise, > they may corrupt your crashdump before the host had a chance to collect > all pieces. Synchronous signaling to the hypervisor is a bit safer. You could NMI-IPI them. But I agree a synchronous signal is better (note it's not race-free itself). -- error compiling committee.c: too many arguments to function From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:41763) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QYiC9-0004fH-2W for qemu-devel@nongnu.org; Mon, 20 Jun 2011 13:23:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QYiC7-0006Bo-J1 for qemu-devel@nongnu.org; Mon, 20 Jun 2011 13:23:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11420) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QYiC7-0006Bi-5J for qemu-devel@nongnu.org; Mon, 20 Jun 2011 13:23:27 -0400 Message-ID: <4DFF8208.7060401@redhat.com> Date: Mon, 20 Jun 2011 20:23:20 +0300 From: Avi Kivity MIME-Version: 1.0 References: <1308577094-17551-1-git-send-email-gollub@b1-systems.de> <20110620153825.GH13042@redhat.com> <4DFF6B20.7090107@redhat.com> <201106201826.32975.gollub@b1-systems.de> <4DFF76B1.8020509@redhat.com> <4DFF7FD0.4070002@siemens.com> In-Reply-To: <4DFF7FD0.4070002@siemens.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/2] Introduce panic hypercall List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Daniel Gollub , qemu-devel , kvm@vger.kernel.org On 06/20/2011 08:13 PM, Jan Kiszka wrote: > > A watchdog has the advantage that is also detects lockups. > > > > In fact you could implement the panic device via the existing > > watchdogs. Simply program the timer for the minimum interval and > > *don't* service the interrupt. This would work for non-virt setups as > > well as another way to issue a reset. > > If you manage to bring down the other guest CPUs fast enough. Otherwise, > they may corrupt your crashdump before the host had a chance to collect > all pieces. Synchronous signaling to the hypervisor is a bit safer. You could NMI-IPI them. But I agree a synchronous signal is better (note it's not race-free itself). -- error compiling committee.c: too many arguments to function