Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030918Ab2B2KQW (ORCPT ); Wed, 29 Feb 2012 05:16:22 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:61690 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1030332Ab2B2KQU (ORCPT ); Wed, 29 Feb 2012 05:16:20 -0500 Message-ID: <4F4DFB37.8060208@cn.fujitsu.com> Date: Wed, 29 Feb 2012 18:17:27 +0800 From: Wen Congyang User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: Avi Kivity CC: Gleb Natapov , kvm list , KAMEZAWA Hiroyuki , "Daniel P. Berrange" , linux-kernel@vger.kernel.org, qemu-devel Subject: Re: [PATCH] kvm: notify host when guest paniced 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> In-Reply-To: <4F4DF913.5030809@redhat.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-02-29 18:14:27, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-02-29 18:14:32, Serialize complete at 2012-02-29 18:14:32 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1772 Lines: 48 At 02/29/2012 06:08 PM, Avi Kivity Wrote: > On 02/29/2012 12:05 PM, Gleb Natapov wrote: >> On Wed, Feb 29, 2012 at 12:00:41PM +0200, Avi Kivity wrote: >>> On 02/29/2012 11:55 AM, Gleb Natapov wrote: >>>>>> >>>>> >>>>> How about using a virtio-serial channel for this? You can transfer any >>>>> amount of information (including the dump itself). >>>>> >>>> Isn't it unreliable after the guest panicked? >>> >>> So is calling hypercalls, or dumping, or writing to the screen. Of >>> course calling a hypercall is simpler and so is more reliable. >>> >> 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... > >>>> 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. Thanks Wen Congyang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/