On Tue, Nov 21, 2017 at 11:24:06 +0000, Daniel Berrange wrote:
On Tue, Nov 14, 2017 at 02:45:08PM +0100, Pavel Hrdina wrote:
If there is no sound device configured for the guest we can disable the audio output because hot-plugging sound devices isn't supported.
Are you sure about that. While libvirt may not have wired up ability to hotplug sound devices, I'm pretty sure that QEMU is able to hotplug them.
At least the USB sound card should allow hotplug in qemu, so I agree with this... On the other hand the output should be a property which can be configured individually for every sound card. I think it's desirable to have a soundcard dedicated to one output method and a second one for a different output method and let the guest OS decide on which cards the sound will play.
Ff libvirt forceably disables the audio backend, now, and then future libvirt enables the pre-existing QEMU support for hotplug, existing VMs will be doomed.
IOW, I don't think this patch is desirable.
We could allow hotplug only if qemu will allow to specify the sound output per-soundcard which would avoid this problem.