Issue with noVNC when pass-through PCI GPU is set on primary

[bellocarico]

I've tried to summaries the issue in the title. Essentially following some background investigation on the amount of CPU demand while the Windows 11 VM is idle I ended up enabling the option "Primary GPU" on the pass-through PCI video card.

This reduced the CPU demand where it should be but now noVNC is completely unusable (Failed connect to vncproxy).

Is there a workaround for this case?

Thanks

 

[leesteken]

I can only confirm that enabling Primary GPU disables the virtual display (which you select in the Display setting). That's probably why the CPU load was reduced: the CPU is no longer used to draw the virtual display.
I don't think you can have it both ways with Proxmox. Either there is a virtual display rendered by the CPU that can be viewed by noVNC (or SPICE) or the GPU is used to render to a physical display.
Other remote desktop software like RDP and Parsec, Steam Link and Looking Glass are capable to show you the GPU rendered display remotely.

 

[bellocarico]

I can only confirm that enabling Primary GPU disables the virtual display (which you select in the Display setting). That's probably why the CPU load was reduced: the CPU is no longer used to draw the virtual display.
I don't think you can have it both ways with Proxmox. Either there is a virtual display rendered by the CPU that can be viewed by noVNC (or SPICE) or the GPU is used to render to a physical display.
Other remote desktop software like RDP and Parsec, Steam Link and Looking Glass are capable to show you the GPU rendered display remotely.

Thanks for the answer that makes sense. Taking a different approach: could I share a GTX1070 at hypervisor level (so no passthrough but sharing the same GPU amongst multiple VMs)? Vmware could do that but had some nasty NVIDIA licenses implication I seem to remember....

 

[leesteken]

could I share a GTX1070 at hypervisor level (so no passthrough but sharing the same GPU amongst multiple VMs)?

I have not experience with this, sorry. For NVidia, the manual mentions GRID, so probably not.

EDIT: There might be some more information on this forum about it.