Support for more audio devices in qemu and examples

[afbjorklund]

Description

Current the intel-hda virtual hardware is hardcoded, and there is no config or example for virtio.

"Intel HD Audio Controller and HDA codec"

It would be good with some config, and an option to select virtio-sound for qemu (just as in vz)

And then an example with paravirtualized sound.

Not sure if alsa is still the best, or try pulseaudio?

• Can't find any ALSA soundcard #3729
• Pulseaudio on container #1107

NOTE: virtio-sound appeared in QEMU 8.2.0 (2023)

It needs a guest OS kernel with CONFIG_SND_VIRTIO

[afbjorklund]

These are the legacy device and codec:

name "intel-hda", bus PCI, desc "Intel HD Audio Controller (ich6)"
name "ich9-intel-hda", bus PCI, desc "Intel HD Audio Controller (ich9)"

name "hda-duplex", bus HDA, desc "HDA Audio Codec, duplex (line-out, line-in)"
name "hda-micro", bus HDA, desc "HDA Audio Codec, duplex (speaker, microphone)"
name "hda-output", bus HDA, desc "HDA Audio Codec, output-only (line-out)"

And these are the paravirtualized virtio:

name "virtio-sound-device", bus virtio-bus

name "virtio-sound-pci", bus PCI, alias "virtio-sound", desc "Virtio Sound"

We have already used the name Device for the audiodev, so the device needs to be called something like Interface...

https://www.qemu.org/docs/master/system/devices/virtio-snd.html

-audiodev alsa,id=my_audiodev
-device virtio-sound-device,streams=1
-device virtio-sound-pci,audiodev=my_audiodev

audio:
  # EXPERIMENTAL
  # QEMU audiodev, e.g., "none", "coreaudio", "pa", "alsa", "oss".
  # VZ driver, use "vz" as device name
  # Choosing "none" will mute the audio output, and not play any sound.
  # Choosing "default" will pick a suitable choice of: coreaudio, pa, dsound, oss.
  # As of QEMU v6.2 the default is to create a disconnected sound device
  # that is still visible in the guest but not connected to the host.
  # 🟢 Builtin default: ""
  device: null
  # QEMU device, e.g. "hda" (the default) or "virtio"
  # VZ driver, use "virtio" as interface
  # 🟢 Builtin default: ""
  interface: null

[afbjorklund]

Currently we don't have an option to enable microphone, and it seems that we only do mono channel on VZ?

https://developer.apple.com/documentation/virtualization/vzvirtiosounddeviceconfiguration

https://developer.apple.com/documentation/virtualization/vzvirtiosounddeviceoutputstreamconfiguration

Should probably make all drivers have the same default, which currently is to create the hardware disconnected?

https://developer.apple.com/documentation/virtualization/vzaudiooutputstreamsink

https://developer.apple.com/documentation/virtualization/vzvirtiosounddeviceoutputstreamconfiguration

---

There seems to be some bug with VZ at the moment, where we are creating the audio device in two places?

pkg/driver/vz/vm_darwin.go=func attachAudio(inst *store.Instance, config *vz.VirtualMachineConfiguration) error {
pkg/driver/vz/vm_darwin.go:             outputStream, err := vz.NewVirtioSoundDeviceHostOutputStreamConfiguration()
pkg/driver/vz/vm_darwin.go=func attachOtherDevices(_ *store.Instance, vmConfig *vz.VirtualMachineConfiguration) error {
pkg/driver/vz/vm_darwin.go:     outputStream, err := vz.NewVirtioSoundDeviceHostOutputStreamConfiguration()