From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dustin Kirkland Subject: Re: [PATCH] qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back to non-accelerated mode Date: Fri, 04 Sep 2009 11:06:38 -0500 Message-ID: <1252080398.4625.47.camel@x200> References: <1252008114.3084.136.camel@blaa> <5d6222a80909031518h2bf804fbk1f7a52424d3e8649@mail.gmail.com> <1252048961.3144.8.camel@blaa> Reply-To: kirkland@canonical.com Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-lIKkxHcfp9j8wJTKjHnF" Cc: Glauber Costa , qemu-devel@nongnu.org, kvm@vger.kernel.org To: Mark McLoughlin Return-path: Received: from adelie.canonical.com ([91.189.90.139]:52060 "EHLO adelie.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753631AbZIDQGq (ORCPT ); Fri, 4 Sep 2009 12:06:46 -0400 In-Reply-To: <1252048961.3144.8.camel@blaa> Sender: kvm-owner@vger.kernel.org List-ID: --=-lIKkxHcfp9j8wJTKjHnF Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Fri, 2009-09-04 at 08:22 +0100, Mark McLoughlin wrote: > 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 wr= ote: > > >> On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: > > >>> qemu-kvm: fix segfault when running kvm without /dev/kvm, falling b= ack > > >>> 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 la= te > > >>> in vl.c. This patch moves the kvm initialization a bit higher in t= he > > >>> 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 soluti= on. > > >> > > >> 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 mos= t > > > 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 =3D> try kvm, try kqemu, try tcg > > >> * --accelmode arg given =3D> 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 wher= e I left Thanks for the pointer, Glauber. My cycles a bit constrained too, but I'll have a look when I get a chance. > In the meantime, can we commit to stable-0.11 either Dustin's fix or > this: >=20 > http://git.et.redhat.com/?p=3Dqemu-fedora.git;a=3Dcommitdiff;h=3Daa1620= 047b +1. We're looking for something agreeable in stable-0.11, that solves the segfault and proceeds without VT acceleration. --=20 :-Dustin Dustin Kirkland Canonical, LTD kirkland@canonical.com GPG: 1024D/83A61194 --=-lIKkxHcfp9j8wJTKjHnF Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEABECAAYFAkqhOw4ACgkQs7pNXIOmEZQ5gQCdEVkQxabMSWzUZB3ZLTehlGAb MzEAoMhXsADUNnRPaI/5CcA4m7Xeui0p =c4Oz -----END PGP SIGNATURE----- --=-lIKkxHcfp9j8wJTKjHnF--