Another passthrough issue: Audio causing slowdown even after applying known fixes

[dakazze]

Hey guys!

I have done GPU passthrough setups several times but this time I am quite stuck.

• PVE 8.2
• Intel I7 4765t
• Currently only running 1 VM for testing

agent: 1
balloon: 0
bios: ovmf
boot: order=scsi0;net0
cores: 5
cpu: host
efidisk0: local-zfs:vm-101-disk-0,efitype=4m,pre-enrolled-keys=1,size=1M
hostpci0: 0000:00:02,pcie=1,rombar=0,x-vga=1
hostpci1: 0000:00:03,pcie=1
machine: q35
memory: 10240
meta: creation-qemu=9.0.2,ctime=1728954259
name: buntuJelly
net0: virtio=BC:24:11:A6:A1:CC,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
parent: predriver
scsi0: NAS:101/vm-101-disk-0.qcow2,iothread=1,size=16G
scsihw: virtio-scsi-single
smbios1: uuid=bab57786-cc6c-486c-8683-ab370a349d74
sockets: 1
usb0: host=3-2
usb1: host=04d9:1512
vga: none
vmgenid: f5693923-fa90-49ad-a5e0-dd6bba99a84c

root=ZFS=rpool/ROOT/pve-1 boot=zfs quiet intel_iommu=on iommu=pt nofb nomodeset video=efifb:off video=vesafb:off

00:02.0 VGA compatible controller [0300]: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller [8086:0412] (rev 06)
00:03.0 Audio device [0403]: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller [8086:0c0c] (rev 06)

I know that the hardware is lacking but this is just a small off-site backup and I want to use it as a media player for Jellyfin, which should be perfectly doable. Video output over display port is working fine but there are audio issues. Audio is causing major slowdowns/stutter and only when I set audio output to 5.1 it is working somewhat okay.

As you see GPU/Audio is recognized wrong on the host and also on the gues it shows up as Xeon E3-1200 though I dont know if that has anything to do with the issues at hand.

Before applying the known fix from the wiki inside the guest:
echo "options snd-hda-intel enable_msi=1" >> /etc/modprobe.d/snd-hda-intel.conf


.... audio was not working at all and slowdowns were even worse.

CPU/RAM utilization stay below 50% even when playing back high bitrate 4k video at 1080p.


Since I already spent hours on this I would appreciate any help I can get! If you think it is an OS issue, I would not mind to switch to anything else since the only purpose of this machine is to play jellyfin.

 

[dakazze]

I did a bit more research and both GPU and HD-Audio are a completely differenct model from the ones that get recognize by proxmox. Detected GPU is P4600 and in reality it is HD4600.
I guess that might be the issue why the guest is using the wrong driver. Any solution to get PVE to detect the correct devices?

 

[dakazze]

Looks like my issues are gone!

After changing the machine settings from Q35 to

machine: q35,viommu=intel

everything runs smooth as butter!
Now the question is if it makes sense to use the same setting for my main PVE machine that does the video transcoding on a Xeon-2176.

 

[dakazze]

Back to square 1 with a Win10 VM....

After researching and trying half a day I am back with another passthrough issue.

I tried getting a Win 10 VM to run and I managed to get a video signal through the Display port but whatever I do I cant get audio over HDMI to work
I did not post a VM config here because I have 2 installs, one with SeaBIOS, one with UEFI and I tried all machine types and different versions as well.

Thats the args I am working with but I also already tried deleteing the second device and added the HDMI audio via the GUI. I know that the host setup and the hardware are okay because I got audio on the ubuntu VM

args: -device "vfio-pci,host=00:02.0,addr=0x02,x-vga=off,x-igd-gms=1,rombar=1,x-igd-opregion=on" -device "vfio-pci,host=00:03.0,addr=0x03"

Windows device manager shows a intel audio device but in the taskbar it says that there is no audio device detected, I also already tried different drivers without any success.

 

[leesteken]

I managed to get a video signal through the Display port but whatever I do I cant get audio over HDMI to work

I have read here before that HDMI of integrated Intel graphics sometimes requires a patched ROM file. I don't know the details (as I don't have Intel) but maybe you can find the relevant threads somewhere on this forum?

 

[dakazze]

I have read here before that HDMI of integrated Intel graphics sometimes requires a patched ROM file. I don't know the details (as I don't have Intel) but maybe you can find the relevant threads somewhere on this forum?

Thank you very much, at least this gives me another angle to try, I will start researching into this and maybe someone can chime in who already has hands on experience with this.