[libvirt] [PATCH 4/6] qemu: Implement startupPolicy for USB passed through devices

[Jiri Denemark]

On Wed, Oct 10, 2012 at 16:39:06 +0100, Daniel P. Berrange wrote:
> On Tue, Oct 09, 2012 at 02:13:25PM +0200, Jiri Denemark wrote:
> > 
> > +    virBufferAddLit(&buf, "usb-host");
> > +    if (!dev->missing) {
> > +        virBufferAsprintf(&buf, ",hostbus=%d,hostaddr=%d",
> > +                          dev->source.subsys.u.usb.bus,
> > +                          dev->source.subsys.u.usb.device);
> > +    }
> > +    virBufferAsprintf(&buf, ",id=%s", dev->info->alias);
> 
> I'm curious about this - it will result in
> 
>    -device  usb-host,id=XXXXX
> 
> shouldn't we actually just leave out the entire arg. I'm not sure
> what QEMU would do with such a device specification.

According to Gerd (and my testing) it's the desired command line. QEMU needs
to know about the usb-host device during incoming migration to avoid aborting
on unknown section in migration data. It's not necessary when starting a
domain from scratch but it doesn't seem to cause any harm.

Jirka