From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:47578) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SAOF2-0004a5-9d for qemu-devel@nongnu.org; Wed, 21 Mar 2012 12:18:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SAOEw-00013k-1G for qemu-devel@nongnu.org; Wed, 21 Mar 2012 12:18:27 -0400 Received: from mail-gx0-f173.google.com ([209.85.161.173]:59097) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SAOEv-00010U-Ox for qemu-devel@nongnu.org; Wed, 21 Mar 2012 12:18:21 -0400 Received: by ggnj2 with SMTP id j2so1276496ggn.4 for ; Wed, 21 Mar 2012 09:18:18 -0700 (PDT) Message-ID: <4F69FF48.3010200@acm.org> Date: Wed, 21 Mar 2012 11:18:16 -0500 From: Corey Minyard 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> In-Reply-To: <20120321091127.GO22368@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked Reply-To: minyard@acm.org List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: kvm list , Jan Kiszka , "linux-kernel@vger.kernel.org" , qemu-devel , Avi Kivity , KAMEZAWA Hiroyuki > 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. -corey