libvirt: xen: Use of vfb in HVM definitions causes xenbus errors

The following changes will prevent the vkbd device from being created (or it will be removed when updating the instance configuration). Right now, waiting on some upstream feedback. Depending on that outcome, I would proceed and try to submit this upstream.

Hi Stefan,

to be clear, would you like this to be rolled into our package while you try to get it upstream? Or should that also await feedback?

On on hand some upstream feedback would be nice, even for the Ubuntu package. On the other side this only affects creation and modification of HVM instances via libvirt. Which I was able to verify and it is working. So missing feedback should not prevent us from using / applying it. The main worry would be whether this change works / is correct with newer versions of Xen as well (which is not really an issue for the Precise package).
So I think it should be safe to upload the package. It is not install critical and could be done with the updates. But then there are those that won't pull in any of those and still complain if things don't work. The effect is not critical either. Just about a 5 minute delay until the xenbus startup fails. And when shutting down during that time, there is additional errors. So I just think, if we can do better, why not.

To be more clear: yes...

Hm hold back, just saw a reply to my question and it sounds like from the Xen side the preferred way may be to change the kernel in a way that avoids the delays.

Ok, it seems I just was too confusing when I tried to explain the problem.

"So the argument is that ATM libvirt uses a vfb config line with HVM guests and that is wrong. I agree with you there, the vfb config line is for PV guests only and should be removed from any HVM guests configurations."

I will work on an upstreamable version of that, but we can go ahead and roll the attached change into our package. (upstream code changed code wise, so the patch won't apply there).

This bug was fixed in the package libvirt - 0.9.8-2ubuntu16

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libvirt (0.9.8-2ubuntu16) precise; urgency=low

  [ Serge Hallyn ]
  * Apply patches from Josh Durgin <email address hidden> to make
    attaching rbd volumes and taking snapshots of them work.
    - ubuntu/9022-qemu-unescape-HMP-commands-before-converting-them-to.patch
    - ubuntu/9023-qemu-change-rbd-auth_supported-separation-character-.patch
    - ubuntu/9024-qemu-allow-snapshotting-of-sheepdog-and-rbd-disks.patch
    - ubuntu/9025-qemu-change-rbd-auth_supported-separation-character-.patch

  [ Stefan Bader ]
  * Do not use vfb sections in HVM graphics definitions (side-
    effect will create a vkbd device as well which causes error
    messages in the HVM guest). (LP: #973529)
 -- Serge Hallyn <email address hidden> Thu, 05 Apr 2012 11:43:15 -0500