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Fran

Member

Registered: 2017-08-23

Posts: 15

qemu-4.0: soundcard passthrough does not work (works in qemu-3.1)

In qemu-3.1 I can passthrough the integrated soundcard to windows without problems with:

  echo vfio-pci > /sys/bus/pci/devices/0000:00:1b.0/driver_override
  echo 0000:00:1b.0 > /sys/bus/pci/devices/0000:00:1b.0/driver/unbind
  echo 0000:00:1b.0 > /sys/bus/pci/drivers_probe
  qemu-system-x86_64 [...] -device vfio-pci,host=0000:00:1b.0 [...]

Today qemu was updated to 4.0 and although GPU passthrough still works fine, soundcard passthrough stopped working. Windows 10 does not see any soundcard device. Downgrading to 3.1 fixes the issue.

Note that in both cases (qemu-3.1 and qemu-4.0) vfio-pci is in use:

$ lspci -nnk -s 0000:00:1b.0
00:1b.0 Audio device [0403]: Intel Corporation 9 Series Chipset Family HD Audio Controller [8086:8ca0]
	Subsystem: ASUSTeK Computer Inc. 9 Series Chipset Family HD Audio Controller [1043:860b]
	Kernel driver in use: vfio-pci
	Kernel modules: snd_hda_intel

Anyone else?

(edit) BTW, I've been testing the emulated audio in 4.0

-audiodev pa,id=pa1,server=/run/user/1000/pulse/native -soundhw hda

and the sound is perfect: as good as passthrough (no crackles or noises as in previous qemu versions), and without the hassle of losing the audio in the host. The only downside is high CPU usage (~10%) for the pulseaudio process. So I'll continue to use 4.0 with emulated sound. I won't mark this as solved though, since the issue persists.

Last edited by Fran (2019-04-27 10:17:41)

malcontent

Member

Registered: 2017-09-27

Posts: 12

Re: qemu-4.0: soundcard passthrough does not work (works in qemu-3.1)

Do you happen to know if this solution works for input as well? E.g. transmitting your voice over microphone.

I tried to do this before but I couldn't get it to work.