[fedora-virt] [fedora-specific libvirt PATCH] qemu: replace deprecated fedora-13 machine type with pc-0.13

[Eric Blake]

On 12/09/2011 09:33 AM, Eric Blake wrote:
>>> Except for the missing gating, it looks reasonable; I'll take some time
>>> to test a domain snapshot taken before the patch and loaded after and
>>> report back with that (but at first glance, it should work).
>>>
>>
>>
>> It may also be useful to start a domain running prior to the upgrade, 
>> then do a snapshot after the upgrade is finished and see if it gets the 
>> right machine type in the xml that's stored in the snapshot file.
> 
> Yep, I'll include that in my testing results.

Testing results - upgrading libvirtd with a running domain of type
fedora-13 passed, and I noticed all persistent configurations were
properly upgraded as part of the new libvirtd.  All attempts to modify a
running fedora-13 machine were converted to pc-0.13, as expected by the
code.

HOWEVER, pc-0.13 is wrong.  I had one rather significant test failure:

I did this on a running domain:
old libvirt: virsh save dom file.sav
upgrade libvirtd
new libvirt: virsh restore file.sav

and got a cryptic failure:

error: Failed to restore domain from file.sav
error: internal error process exited while connecting to monitor: char
device redirected to /dev/pts/5
Unknown savevm section or instance 'kvmclock' 0
load of migration failed

But I then hand-hacked the save file (well, actually, I did:

sed "s/='fedora-13'/='pc-0.14'  /" file.sav > file.sav2

at which point:
new libvirt: virsh restore file.sav2

succeeded.  My conclusion?  Qemu must be saving the machine type
somewhere in the migration file format (virsh save is a migration to
file, which means you'd see the same behavior when migrating between two
machines); and pc-0.13 is missing something related to kvmclock, and is
thus unable to reparse the migration data.  But pc-0.14 works just fine,
which means your patch is _almost_ right - just change fedora-13 to
pc-0.14, and I think we're set.

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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