From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark McLoughlin Subject: Re: virtio breakage with 2.6.25 guest kernel Date: Wed, 14 Jan 2009 09:22:58 +0000 Message-ID: <1231924978.4944.76.camel@localhost.localdomain> References: <496C9813.7000609@suse.de> <496CF614.5000405@codemonkey.ws> <2D739E97-509B-4523-B04B-B18364C152EB@suse.de> Reply-To: Mark McLoughlin Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Anthony Liguori , kvm-devel , "qemu-devel@nongnu.org" , "rusty@rustcorp.com.au" To: Alexander Graf Return-path: Received: from mx2.redhat.com ([66.187.237.31]:59036 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753852AbZANJXM (ORCPT ); Wed, 14 Jan 2009 04:23:12 -0500 In-Reply-To: <2D739E97-509B-4523-B04B-B18364C152EB@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, 2009-01-13 at 22:05 +0100, Alexander Graf wrote: > On 13.01.2009, at 21:14, Anthony Liguori wrote: > > > Alexander Graf wrote: > >> Hi, > >> > >> while I don't fully understand the problem, here's what I > >> experience so far: > >> > >> When using an openSUSE 11.0 kernel (2.6.25) in the guest, virtio on > >> tap > >> breaks with current KVM git, while it used to work before (haven't > >> bisected, definitely worked in kvm-78, but is probably due to > >> Anthony's > >> rewrite). It shows the following message (comes from qemu): > >> > > > > There were a couple of old-guest-breaking regressions. I think > > we've fixed all of them but there could be more. Are you using the > > latest kvm-userspace? See: http://lists.gnu.org/archive/html/qemu-devel/2009-01/msg00574.html > This one is definitely due to the broken guest kernel. I applied the > patch mark mentioned to ours and things started working. > > So the only way I can think of to 'fix' it is by detecting broken > guests. We could supply a host mask of 0xffffffff and see if tge guest > feature mask is tge same. If so, feature masking is probably broken. Nice idea, but no way of making the guest through feature detection negotiation, I don't think. Cheers, Mark.