From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark McLoughlin Subject: Re: [PATCH] qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back to non-accelerated mode Date: Fri, 04 Sep 2009 08:22:41 +0100 Message-ID: <1252048961.3144.8.camel@blaa> References: <1252008114.3084.136.camel@blaa> <5d6222a80909031518h2bf804fbk1f7a52424d3e8649@mail.gmail.com> Reply-To: Mark McLoughlin Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Dustin Kirkland , qemu-devel@nongnu.org, kvm@vger.kernel.org To: Glauber Costa Return-path: Received: from mx1.redhat.com ([209.132.183.28]:57584 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752092AbZIDHXl (ORCPT ); Fri, 4 Sep 2009 03:23:41 -0400 In-Reply-To: <5d6222a80909031518h2bf804fbk1f7a52424d3e8649@mail.gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, 2009-09-03 at 19:18 -0300, Glauber Costa wrote: > On Thu, Sep 3, 2009 at 6:48 PM, Dustin Kirkland wrote: > > On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin wrote: > >> On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: > >>> qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back > >>> to non-accelerated mode > >>> > >>> We're seeing segfaults on systems without access to /dev/kvm. It > >>> looks like the global kvm_allowed is being set just a little too late > >>> in vl.c. This patch moves the kvm initialization a bit higher in the > >>> vl.c main, just after options processing, and solves the segfaults. > >>> We're carrying this patch in Ubuntu 9.10 Alpha. Please apply > >>> upstream, or advise if and why this might not be the optimal solution. > >> > >> Ah discussion about an alternative fix for this fizzled out recently: > >> > >> http://www.mail-archive.com/kvm@vger.kernel.org/msg19890.html > > > > Ah, thanks Mark. In that thread, I found Daniel's suggestion the most > > reasonable, and user-friendly: > > > > On Mon, Jul 27, 2009 at 1:44 PM, Daniel P. Berrange wrote: > >> Well, we could go for logic like: > >> > >> * No arg given => try kvm, try kqemu, try tcg > >> * --accelmode arg given => try $arg, and fail if unavailable > >> > >> then libvirt would simply always supply --accelmode for all VMs, > >> while people running qemu manually would get best available > I sent some patches to do that, but they were incomplete, and I was > preempted by something else. > If you want, you can wait for my cycles to come back, or pick from where I left In the meantime, can we commit to stable-0.11 either Dustin's fix or this: http://git.et.redhat.com/?p=qemu-fedora.git;a=commitdiff;h=aa1620047b Cheers, Mark.