Hi there,

 

I've managed to get an Ubuntu 20.04 LTS VM running with a GPU and a USB card passed through with no issues - except that all sound output onto the NVIDIA audio controller sounds like the Terminator having a stroke. It's not just distorted, it's a single tone of varying pitch with a stutter effect on top that persists for a couple seconds after the sound source stops playing. I tried a USB sound card, and it sounds fine.

 

I'm running an ASUS TUF Gaming X570-Plus with a Ryzen 5 3600, an NVIDIA NVS 310 in the primary slot and an NVIDIA NVS 510 in the secondary slot, plus a PCI USB card. The 510 graphics and audio and the USB card are passed through.

 

Relevant IOMMU groups:

IOMMU group 21:

[10de:0ffd] 03:00.0 VGA compatible controller: NVIDIA Corporation GK107 [NVS 510] (rev a1)

[10de:0e1b] 03:00.1 Audio device: NVIDIA Corporation GK107 HDMI Audio Controller (rev a1)

IOMMU group 22:

[1106:3483] 04:00.0 USB controller: VIA Technologies, Inc. VL805 USB 3.0 Host Controller (rev 01)

IOMMU group 24: (just for info)

[10de:107d] 09:00.0 VGA compatible controller: NVIDIA Corporation GF119 [NVS 310] (rev a1)

[10de:0e08] 09:00.1 Audio device: NVIDIA Corporation GF119 HDMI Audio Controller (rev a1)

 

And relevant part of my VM XML:

<hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
      </source>
      <alias name='hostdev0'/>
      <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x03' slot='0x00' function='0x1'/>
      </source>
      <alias name='hostdev1'/>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
      </source>
      <alias name='hostdev2'/>
      <address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/>
    </hostdev>

Thanks in advance for any help or advice!

https://forums.unraid.net/topic/53062-ubuntu-16041-x64-quotdemonicquot-audio/?tab=comments#comment-519239