[SOLVED] Passthrough device added - network adapters disappear

[MisterDeeds]

Hello all

I have a Proxmox host on which I have enabled IOMMU (both bios side and under Proxmox). This seems to work as well.





However, as soon as a passthrough device is added to a VM, the physical network adapters disappear.




Only after deactivating the IOMMU option in the BIOS, the server boots normally (with network connection) and I can remove the device via the web interface.
After that, everything works normally again.

Does anyone have any idea?

Thanks and best regards

 

[Dunuin]

Did you checked that the GPU got its own IOMMU group and is not sharing it with other devices (find /sys/kernel/iommu_groups/ -type l)?

 

[MisterDeeds]

Hi Dunuin

Thank you for the answer. You are right, it is because of the IOMMU groups. The GPU is in its own group, but I have a PCI-E RS232 card that I want to pass through to another VM. This is in the same group as the network adapters.



I tried to write "pcie_acs_override=downstream" in the /etc/kernel/cmdline, unfortunately the groups remain the same

Since it is a rack server with mATX motherboard I have no other PCI-E port free to install the card...

Is there any other way to separate the groups?

 

[MisterDeeds]

if you write too fast and search too little long, sorry!

... now it works:

I also had to put "multifunction" behind it, so like this: pcie_acs_override=downstream,multifunction

Now it works!


Thanks for the hint and best regards