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From: | Rusty Russell |
Subject: | [Qemu-devel] Re: virtio breakage with 2.6.25 guest kernel |
Date: | Thu, 15 Jan 2009 12:47:53 +1030 |
User-agent: | KMail/1.10.3 (Linux/2.6.27-9-generic; KDE/4.1.3; i686; ; ) |
On Wednesday 14 January 2009 19:52:58 Mark McLoughlin wrote: > On Tue, 2009-01-13 at 22:05 +0100, Alexander Graf wrote: > > > On 13.01.2009, at 21:14, Anthony Liguori <address@hidden> 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. Just add a feature "VIRTIO_F_LIES_ABOUT_FEATURES"? No guest should ever set this. But I'm not sure it's worth the pain... Rusty. |
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