From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH 0/2] Introduce panic hypercall Date: Mon, 20 Jun 2011 14:28:42 -0500 Message-ID: <4DFF9F6A.5040201@codemonkey.ws> References: <1308577094-17551-1-git-send-email-gollub@b1-systems.de> <4DFF67CB.3060807@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Daniel Gollub , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mail-pv0-f174.google.com ([74.125.83.174]:41951 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751352Ab1FTT2u (ORCPT ); Mon, 20 Jun 2011 15:28:50 -0400 Received: by pvg12 with SMTP id 12so994374pvg.19 for ; Mon, 20 Jun 2011 12:28:50 -0700 (PDT) In-Reply-To: <4DFF67CB.3060807@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/20/2011 10:31 AM, Avi Kivity wrote: > On 06/20/2011 04:38 PM, Daniel Gollub wrote: >> Introduce panic hypercall to enable the crashing guest to notify the >> host. This enables the host to run some actions as soon a guest >> crashed (kernel panic). >> >> This patch series introduces the panic hypercall at the host end. >> As well as the hypercall for KVM paravirtuliazed Linux guests, by >> registering the hypercall to the panic_notifier_list. >> >> The basic idea is to create KVM crashdump automatically as soon the >> guest paniced and power-cycle the VM (e.g. libvirt). > > This would be more easily done via a "panic device" (I/O port or > memory-mapped address) that the guest hits. It would be intercepted by > qemu without any new code in kvm.\ > > However, I'm not sure I see the gain. Most enterprisey guests already > contain in-guest crash dumpers which provide more information than a > qemu memory dump could, since they know exact load addresses etc. and > are integrated with crash analysis tools. What do you have in mind? FYI, s390 has this functionality. It's useful because there's no use in having a guest just spin in a panic loop. Crash dump integration is much more complicated and requires functioning networking or some paravirt channel. Regards, Anthony Liguori