Re: [dpdk-dev] [libvirt] [RFC] Vhost-user backends cross-version migration support

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Feb 02, 2017 at 03:06:21PM +0000, Daniel P. Berrange wrote:
> On Thu, Feb 02, 2017 at 03:14:01PM +0100, Maxime Coquelin wrote:
> > 
> > 
> > On 02/01/2017 12:41 PM, Daniel P. Berrange wrote:
> > > 
> > > It depends where / how in OVS it needs to be set. The only stuff libvirt
> > > does with OVS is to run 'add-port' and 'del-port' commands via the ovs
> > > cli tool. We pass through arguments from the port profile stored in the
> > > XML config.
> > > 
> > >   <interface type='bridge'>
> > >     <source bridge='ovsbr'/>
> > >     <virtualport type='openvswitch'>
> > >       <parameters profileid='menial' interfaceid='09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f'/>
> > >     </virtualport>
> > >   </interface>
> > > 
> > > eg those things in <parameters/> get passed as cli args to the 'add-port'
> > > command. Soo if add-port needs this new version string, then we'd need
> > > to add the version to the openvswitch virtualport XML.
> > > 
> > > If the version is provided to OVS in a different command, then it would
> > > probably be outside scope of libvirt.
> > 
> > I think it would make sense to be a parameter of the add-port command.
> > But it would be for vhost-user related add-port command, I didn't find
> > where/if this is managed in libvirt XML.
> 
> For vhost-user, libvirt does not have any interaction with OVS at
> all. If the thing that's using the vhost-user UNIX socket, in turn
> connects to OVS, that's outside scope of libvirt. IOW, for vhost-user
> OVS it seems like that job is for Nova / os-vif to solve.
> 
> Regards,
> Daniel

I don't think they currently understand the issues involved in
cross-version migration though.  This is a complex subject and easy to
get wrong.  It would be significantly better to figure it out at libvirt
level since it already deals with cross-version migration issues.


> -- 
> |: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
> |: http://libvirt.org              -o-             http://virt-manager.org :|
> |: http://entangle-photo.org       -o-    http://search.cpan.org/~danberr/ :|