Re: [Qemu-devel] [libvirt] [PULL 25/26] block: Remove deprecated -drive option serial

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Jun 22, 2018 at 04:19:29PM +0200, Markus Armbruster wrote:
> Kevin Wolf <kwolf@redhat.com> writes:
> 
> > Am 22.06.2018 um 13:38 hat Christian Borntraeger geschrieben:
> >> 
> >> On 06/15/2018 04:21 PM, Kevin Wolf wrote:
> >> > The -drive option serial was deprecated in QEMU 2.10. It's time to
> >> > remove it.
> >> > 
> >> > Tests need to be updated to set the serial number with -global instead
> >> > of using the -drive option.
> >> 
> >> libvirt 4.5 still creates those (at least on s390x)
> >> 
> >>     <disk type='file' device='disk'>
> >>       <driver name='qemu' type='qcow2' cache='none' io='native' iothread='1'/>
> >>       <source file='/var/lib/libvirt/qemu/image.zhyp137'/>
> >>       <target dev='hda' bus='virtio'/>
> >>       <serial>skel</serial>
> >>       <boot order='1'/>
> >>       <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0000'/>
> >>     </disk>
> >> 
> >> 
> >> -> 
> >> [...]
> >> -drive file=/var/lib/libvirt/qemu/image.zhyp137,format=qcow2,if=none,id=drive-virtio-disk0,serial=skel,cache=none,aio=native -device virtio-blk-ccw,iothread=iothread1,scsi=off,devno=fe.0.0000,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1,write-cache=on 
> >> [...]
> >> 
> >> 2018-06-22T11:25:20.946024Z qemu-system-s390x: -drive file=/var/lib/libvirt/qemu/image.zhyp137,format=qcow2,if=none,id=drive-virtio-disk0,serial=skel,cache=none,aio=native: Block format 'qcow2' does not support the option 'serial'
> >> 2018-06-22 11:25:21.098+0000: shutting down, reason=failed
> >> 
> >> So it seems that this breaks s390x.
> >
> > Thanks for bringing this up. libvirt should fix this before QEMU 3.0 is
> > released.
> >
> > Sadly, it also shows that deprecation warnings in log files go
> > unnoticed.
> 
> Nobody reads log files until things have gone belly up, and even then
> unrelated log entries get ignored.
> 
> The way to get deprecation warnings noticed it to have the management
> application fail its "make check".
> 
> Perhaps we could use a more structured notification, to make detecting
> use of deprecated features programmatically trivial.  A QMP event might
> do.

Libvirt currently has CI that is largely focused on unit testing. We
recently did some work, however, to get our functional test suite
working properly again (Sys-Virt-TCK) and are trying to get some
new CI hardware. So if we get that running, we coud run tests on real
QEMU versions and check the /var/log/libvirt/qemu/$GUEST.logs to
make sure we're not triggering unexpected warnings from QEMU

Regards,
Daniel
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