Re: [Qemu-devel] [PATCH] virtio-serial: add enable_backend callback

[Michael S. Tsirkin]

On Mon, Jul 10, 2017 at 04:13:54PM +0200, Laurent Vivier wrote:
> >  static void virtconsole_realize(DeviceState *dev, Error **errp)
> >  {
> >      VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
> > @@ -233,6 +253,7 @@ static void virtserialport_class_init(ObjectClass 
> > *klass, void *data)
> >      k->unrealize = virtconsole_unrealize;
> >      k->have_data = flush_buf;
> >      k->set_guest_connected = set_guest_connected;
> > +    k->enable_backend = virtconsole_enable_backend;
> 
> Why don't you register a  vm_state change handler to change the state of
> the virtconsole according to the state of the machine instead of adding
> a new function in the VirtIOSerialPortClass?
> 
> See a23a6d1 ("virtio-rng: stop virtqueue while the CPU is stopped")
> 
> Thanks,
> Laurent


In fact that commit does it the wrong way IMHO.

The order of this call wrt other virtio calls is not
guaranteed.

IMHO the right way is to set a vm state change handler in VirtioBusClass
or status change handler in VirtioDeviceClass.

-- 
MST