Got an interesting one:

i9-9900 (Coffee Lake) system w/ i915 graphics. This is a signage type mini PC with an HDMI and two Display Port outputs.

It has space for NVMe and SSD (SATA) drives. Currently have a 500GB NVMe installed on which I installed xcp-ng 8.3/XOA, created an SR on same and put a Linux Mint 22 VM on.

I need to get display outputs from the PC itself as the end user won't understand Xen Orchestra or the rest of the under-the-hood stuff I'm doing with the system. So...isolated the Intel graphics adapter from Dom0, set igd_passthrough=true (via command line on the XOA instance) and added a PCI Device via the VM's Advanced settings.

When xcp-ng starts up the HDMI-connected monitor goes blank as it should. I start the Linux VM via XOA on another system, can get a Login screen and then a desktop.

Display Settings only shows the Console (bochs-drm) driven screen. inxi -G when run from a terminal on the Console screen shows both bochs-drm and i915 drivers loaded, and only the one screen listed.

If I ssh into the system and run inxi -G in the terminal session I see all three physically connected screens listed but no video is displayed on any of them. Doesn't matter if I use Wayland or X11 - results are same; detected monitors are same. Xorg.0.log also shows EDID captures for the two Display Port monitors so I know they're being queried successfully.

Thoughts, suggestions on where to go from here?

Hardware update:

Got a couple M9148 (4 port Matrox DP) and Wavlink WL-UG7500DH (4 port DP/HDMI) in to test.

Configured a Win11 Pro VM with the Matrox driver. It broke the VM so severely that I had to re-pave. So, I pulled the card, swapped for a Wavlink and created another Win11 Pro VM - to which I assigned the Wavlink card and loaded their drivers.

It works flawlessly. Both HDMI displays I had connected were instantly recognized in Device Manager and available.

I then shut it down, created another VM with Mint 22.3 and assigned resources exactly per the Windows machine. Installed the Wavlink Ubuntu driver and DisplayLink. Rebooted.

Still only see the XOA virtual (Console) screen regardless if I have the VM's VGA option turned on or not. The evdi driver is running as is the DisplayLink service. Looking at Xorg.0.log, I see EDID returns for the two HDMI monitors connected to the Wavlink card along with that from the virtual screen - but no screens other than the virtual one show in Display.

Interesting bit: The GT730 card behaves EXACTLY the same way. Works great under Win11, driver initializes correctly in Mint but no display other than virtual.

Going to post something on the DisplayLink support forum but find it odd that two different cards behave the same way in two different OSes.

Meant to update this again last night - as a road map for those who might try similar at some point:

This community's documentation led me to some relevant information on mouse/keyboard pass-through. Namely, if you want this to work you have to pass the entire PCI controller through to the guest(s), Won't work with motherboard devices.

But I'm out of PCIe slots. What to do...

Simple. Chuck the two serial adapters and install two dual USB 2.0 adapters in their places. Connect the keyboard/mouse to one of the ports and a 4/8/16 port USB to serial adapter to the other. Then pass the entire controller through.

In this particular server (R810) I have 5 available PCIe slots. Two will be used for the video cards, one for a 4x NVMe to PCIe adapter (which is eventually where the VMs will reside) and the remaining two for the USB interfaces. This effectively gives me two discrete physical systems, a third available VM instance (say, for network management, monitoring or whatever) and the XOA instance.

For application/radio control systems hypervisors (nested) I'll probably have 2ea Win11 and whatever flavor of Linux that supports the GT730 GPU on the system - each assigned the pass-through devices - but only two running at any given time. So no resource contention issues.

As far as the displays:

I have the main interface of the server connected via SIP to a 2160AS KVM. I'll take 2 more SIPs and use these as the keyboard/mouse inputs for the USB cards. Video...I use an HDMI active splitter on other systems in the network so I'll employ that here. One of the ports on the add-in GPUs goes to the splitter, one of the splitter outputs goes to the SIP via HDMI to VGA adapter and the other feeds the main ceiling mount monitor. The Primary display will be replicated to the KVM screen. Resolution isn't an issue as I have a video scaler inline with the KVM for just this scenario.

The concept could be expanded. I'm looking at picking up a T630 and building 4 effective "systems" out of it, following the same principle. The 630 has 8 available PCIe slots.

Will update when the next batch of hardware arrives - or I get the Linux side of things sorted. That's next.

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.

@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.

@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.

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.