[CentOS-virt] CentOS 6 Xen virt* issues

Tue Sep 29 11:37:25 UTC 2015
George Dunlap <dunlapg at umich.edu>

On Sat, Sep 26, 2015 at 9:29 PM, Pasi Kärkkäinen <pasik at iki.fi> wrote:
> On Sat, Sep 26, 2015 at 09:04:23PM +0300, Pasi Kärkkäinen wrote:
>> Hello,
>> I just upgraded some of my el6xen boxes to latest CentOS 6.7, Xen 4.4.3 and dom0 3.18.17 rpms, and noticed these new problems:
> And third issue aswell:
> 3) Creating an HVM guest using virt-manager with file-based storage uses loopback-mount, not blktap
> When I manually create a new Xen HVM guest using virt-manager, and choose file-based image for storage of the VM, it seems to be set up to use file: backend/driver with loopback-mounted image file:
>     <disk type='file' device='disk'>
>       <driver name='file'/>
>       <source file='/var/lib/libvirt/images/testvm2.img'/>
>       <backingStore/>
>       <target dev='hda' bus='ide'/>
>     </disk>
> # losetup -a
> /dev/loop0: [fd00]:1709109 (/var/lib/libvirt/images/testvm2.img)
> With earlier versions of rpms similar setup used blktap2 backend.. (and yes, I do have blktap module loaded in dom0 kernel).

I remember having to patch some dependency of virt-manager to give it
the correct default driver name (something like, it got 'tap' but
needed to be 'tap2').  In all likelihood, someone has sussed that
'tap' doesn't work and just replaced it with 'file'.  Actually, it's
fairly likely if they've updated stuff in CentOS that you're not
getting the re-build virt-manager stuff either -- I may have to respin
that one as well.

While we're here, could you give me a couple of virt-install and
virt-viewer "smoketest" commands that I could add to my automated test
scripts?  ATM I'm testing libvirt by using virsh to import an xl .cfg
file, but it would be better to have something that created the config
end-to-end.  Using virt-manager directly is probably more work than
I'm up for in most cases, but hopefully if I can test the things it
depends on I can notice this sort of breakage.