From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:48240) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SAOLx-0006sI-GV for qemu-devel@nongnu.org; Wed, 21 Mar 2012 12:25:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SAOLr-0002Vu-Fk for qemu-devel@nongnu.org; Wed, 21 Mar 2012 12:25:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35616) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SAOLr-0002VH-7o for qemu-devel@nongnu.org; Wed, 21 Mar 2012 12:25:31 -0400 Message-ID: <4F6A00EC.3060706@redhat.com> Date: Wed, 21 Mar 2012 18:25:16 +0200 From: Avi Kivity MIME-Version: 1.0 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 Subject: Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: minyard@acm.org Cc: Gleb Natapov , Jan Kiszka , qemu-devel , "linux-kernel@vger.kernel.org" , kvm list , Corey Minyard , KAMEZAWA Hiroyuki 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