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

[Daniel P . Berrangé]

On Fri, Jun 22, 2018 at 03:25:19PM +0100, Daniel P. Berrangé wrote:
> On Fri, Jun 22, 2018 at 04:19:29PM +0200, Markus Armbruster wrote:
> > Kevin Wolf <address@hidden> 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

This could be even easier if there was a --no-deprecations flag to
QEMU which triggered abort() whenever mgmt app uses a deprecated
feature.


Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|