Dual video adapters - what should I see, and where?

FredM273

xcp-ng 8.3 on a Dell R810 w/ Geforce GT730 four port HDMI adapter set up as PCI passthrough. Card has been isolated from Dom0.

Several VMs - one Win11 Pro; others are various Linux Mint versions.

Let's start with the Windows VM. I installed the appropriate NVidia drivers and connected up a few monitors to the card. Device Manager shows the driver as initialized and running.

Initially I accessed the VM from the Xen Orchestra Console and went to Display Settings to check for the presence of multiple displays. Nada - the only one showing was the server's built-in VGA adapter.

I then pressed "Detect other displays" and locked the VM up. Reboots show a black screen in the Console (hadn't checked the HDMI monitors yet; server is remote).

What SHOULD I be seeing here - all the displays listed or just the Console's video device?

I'll touch on the Linux stuff later in thread.

acebmxer

@FredM273

Did you enable PCI-Pass through for the nvida card? If so did you then add the pci card to the vm? the gpu can only be utilized by 1 vm at a time fyi.

https://docs.xcp-ng.org/compute/

FredM273

@acebmxer Certainly did - and got it working in my Windows guest...somewhat. When that VM initializes, all four monitors are activated by the graphics card, and I can log into the VM via an XOA-connected laptop. Can set up the monitors too. But...can only get mouse/keyboard focus on the main display (which I suspect is due to the way XOA Console handles things). So now I have to figure out a way to pass the keyboard and mouse through to the VMs.

The Linux issue I suspect is due to driver signing requirements but at least this part works. There will be two 4-port video cards in the system - one for each VM that's assigned a pass-through device.

acebmxer

@FredM273

Maybe I am a little confused on what you are trying to archive.

The GT730 - https://www.techpowerup.com/gpu-specs/geforce-gt-730.c1988 This is the card correct?

Reguardless of video card passing though. It should behaive simiar to native compuer with gpu and multiple moniors connected. As long as there are monitors connected to the outputs. If passed my gpu just for LLM's not for actuall work. I believe the xcp-ng web console and the first monior connected to video card would mirror themselves.

FredM273

@acebmxer What I'm up to is the following:

Two separate VMs, each with one of these video cards and an 8-port PCIe serial controller assigned. I have 8 monitors for the setup; 4 per VM.

The VMs will be used to run software which controls radio receivers and each display will act as a heads-up for a different instance of the software. I run this particular configuration with a Type 1 hypervisor on smaller systems but this is the first time deploying on larger-scale bare metal.

As further experimentation I put the serial cards in the server and verified via lspci they were there. I ran xen-pciback.hide against each adapter by itself then against all three (including video card, per docs online) and they appear assignable when queried from the hypervisor's local command prompt. But the new cards (serial) don't appear in the drop-down of the Attach PCI section - even after a server reboot.

A somewhat related question on keyboard/mouse pass-through: One has to have a separate mouse/keyboard for EACH VM running on the system in order for this to work properly, I assume? By separate, not the one used to access the hypervisor console itself.

FredM273

I figured out how to get serial and GPU PCIe devices added.

Serial must be done via CLI at the server console. When you access the VM properties with Orchestra you'll see the graphics card has been detached. You can add it back via Attach PCI then both devices will show up as attached.