From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59448) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2gPs-0000QP-W3 for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:05:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S2gPj-0007sa-RM for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:05:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33635) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2gPj-0007s2-G2 for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:05:39 -0500 Message-ID: <4F4DF86C.5010407@redhat.com> Date: Wed, 29 Feb 2012 12:05:32 +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> <20120229095842.GF5050@redhat.com> In-Reply-To: <20120229095842.GF5050@redhat.com> Content-Type: text/plain; charset=UTF-8 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: "Daniel P. Berrange" Cc: qemu-devel , KAMEZAWA Hiroyuki , kvm list , linux-kernel@vger.kernel.org On 02/29/2012 11:58 AM, Daniel P. Berrange wrote: > > > > How about using a virtio-serial channel for this? You can transfer any > > amount of information (including the dump itself). > > When the guest OS has crashed, any dumps will be done from the host > OS using libvirt's core dump mechanism. The guest OS isn't involved > and is likely too dead to be of any use anyway. Likewise it is > quite probably too dead to work a virtio-serial channel or any > similarly complex device. We're really just after the simplest > possible notification that the guest kernel has paniced. If it's alive enough to panic, it's alive enough to kexec its kdump kernel. After that it can do anything. Guest-internal dumps are more useful IMO that host-initiated dumps. In a cloud, the host-initiated dump is left on the host, outside the reach of the guest admin, outside the guest image where all the symbols are, and sometimes not even on the same host if a live migration occurred. It's more useful in small setups, or if the problem is in the hypervisor, not the guest. -- error compiling committee.c: too many arguments to function