From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] kvm: notify host when guest paniced Date: Wed, 29 Feb 2012 12:39:29 +0200 Message-ID: <4F4E0061.1050508@redhat.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , kvm list , KAMEZAWA Hiroyuki , "Daniel P. Berrange" , linux-kernel@vger.kernel.org, qemu-devel To: Wen Congyang Return-path: In-Reply-To: <4F4DFB37.8060208@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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