From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964875Ab2CUQZf (ORCPT ); Wed, 21 Mar 2012 12:25:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57548 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758943Ab2CUQZd (ORCPT ); Wed, 21 Mar 2012 12:25:33 -0400 Message-ID: <4F6A00EC.3060706@redhat.com> Date: Wed, 21 Mar 2012 18:25:16 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 MIME-Version: 1.0 To: minyard@acm.org CC: Corey Minyard , Gleb Natapov , Wen Congyang , kvm list , qemu-devel , "linux-kernel@vger.kernel.org" , "Daniel P. Berrange" , KAMEZAWA Hiroyuki , Jan Kiszka Subject: Re: [PATCH 0/2 v3] kvm: notify host when guest panicked References: <4F58664D.1070800@cn.fujitsu.com> <4F66E14F.3040809@cn.fujitsu.com> <4F6854F4.3060703@cn.fujitsu.com> <20120320154517.GG27928@redhat.com> <4F692723.8050904@cn.fujitsu.com> <20120321091127.GO22368@redhat.com> <4F69FF48.3010200@acm.org> In-Reply-To: <4F69FF48.3010200@acm.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/21/2012 06:18 PM, Corey Minyard wrote: > >> Look at drivers/char/ipmi/ipmi_msghandler.c. It has code to send panic >> event over IMPI. The code is pretty complex. Of course if we a going to >> implement something more complex than simple hypercall for panic >> notification we better do something more interesting with it than just >> saying "panic happened", like sending stack traces on all cpus for >> instance. > > I doubt that's the best example, unfortunately. The IPMI event log > has limited space and it has to be send a little piece at a time since > each log entry is 14 bytes. It just prints the panic string, nothing > else. Not that it isn't useful, it has saved my butt before. > > You have lots of interesting options with paravirtualization. You > could, for instance, create a console driver that delivered all > console output efficiently through a hypercall. That would be really > easy. Or, as you mention, a custom way to deliver panic information. > Collecting information like stack traces would be harder to > accomplish, as I don't think there is currently a way to get it except > by sending it to printk. That already exists; virtio-console (or serial console emulation) can do the job. In fact the feature can be implemented 100% host side by searching for a panic string signature in the console logs. -- error compiling committee.c: too many arguments to function