Add default value for audio driver

Can now use .audio.device=default similar to .video.display=default

You can still pick another driver, such as alsa or oss, if you want.

Signed-off-by: Anders F Björklund <anders.f.bjorklund@gmail.com>

examples/default.yaml

@@ -297,6 +297,9 @@ audio:
   # 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 of: coreudio, 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
 

pkg/qemu/qemu.go

@@ -463,6 +463,19 @@ func qemuMachine(arch limayaml.Arch) string {
 	return "virt"
 }
 
+// audioDevice returns the default audio device.
+func audioDevice() string {
+	switch runtime.GOOS {
+	case "darwin":
+		return "coreaudio"
+	case "linux":
+		return "pa" // pulseaudio
+	case "windows":
+		return "dsound"
+	}
+	return "oss"
+}
+
 func Cmdline(ctx context.Context, cfg Config) (exe string, args []string, err error) {
 	y := cfg.LimaYAML
 	exe, args, err = Exe(*y.Arch)
@@ -762,6 +775,9 @@ func Cmdline(ctx context.Context, cfg Config) (exe string, args []string, err er
 		id := "default"
 		// audio device
 		audiodev := *y.Audio.Device
+		if audiodev == "default" {
+			audiodev = audioDevice()
+		}
 		audiodev += fmt.Sprintf(",id=%s", id)
 		args = append(args, "-audiodev", audiodev)
 		// audio controller