From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:41468) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2gwm-00010P-E9 for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:39:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S2gwg-0006SX-4V for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:39:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:12972) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2gwf-0006SF-Ss for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:39:42 -0500 Message-ID: <4F4E0061.1050508@redhat.com> Date: Wed, 29 Feb 2012 12:39:29 +0200 From: Avi Kivity MIME-Version: 1.0 References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4CB926.6050600@redhat.com> <4F4D7F5E.5040202@cn.fujitsu.com> <4F4DF4C6.90609@redhat.com> <20120229095557.GE24600@redhat.com> <4F4DF749.7060507@redhat.com> <20120229100550.GF24600@redhat.com> <4F4DF913.5030809@redhat.com> <4F4DFB37.8060208@cn.fujitsu.com> In-Reply-To: <4F4DFB37.8060208@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] kvm: notify host when guest paniced List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wen Congyang Cc: Gleb Natapov , kvm list , qemu-devel , linux-kernel@vger.kernel.org, KAMEZAWA Hiroyuki On 02/29/2012 12:17 PM, Wen Congyang wrote: > >>> > >> Yes, crash can be so severe that it is not even detected by a kernel > >> itself, so not OOPS message even printed. But in most cases if kernel is > >> functional enough to print OOPS it is functional enough to call single > >> hypercall instruction. > > > > Why not print the oops to virtio-serial? Or even just a regular serial > > port? That's what bare metal does. > > If virtio-serial's driver has bug or the guest doesn't have such device... We have the same issue with the hypercall; and virtio-serial is available on many deployed versions. > > > >>>> Having special kdump > >>>> kernel that transfers dump to a host via virtio-serial channel though > >>>> sounds interesting. May be that's what you mean. > >>> > >>> Yes. The "panic, starting dump" signal should be initiated by the > >>> panicking kernel though, in case the dump fails. > >>> > >> Then panic hypercall sounds like a reasonable solution. > > > > It is, but I'm trying to see if we can get away with doing nothing. > > > > If we have a reliable way with doing nothing, it is better. But I donot > find such way. We won't have a 100% reliable way. But I think a variant of the driver that doesn't use interrupts, or just using the ordinary serial driver, should be reliable enough. -- error compiling committee.c: too many arguments to function