Ya,
for the working machine I just had to run

opt/xensource/libexec/xen-cmdline --set-dom0 "xen-pciback.hide=(0000:00:02.0)"

and on next reboot I could add the GPU as pass through in XOA. for the other machine this didn’t work but using xcp-center did make it show up as a pass through option

@khumps Turns out that was an issue with missing firmware. XCP-ng center fixed everything

@khumps
I just tried using xcp-ng center and it got it to show up as a passthrough in the gui and I see the device but still no luck getting /dev/dri/ to populate or i915 to load. Is there any diagnostic data or any support I can provide to help this get patched?

Sorry to revive a dead thread but I also am in the same place with the exact same Intel CPU model. My other CPU passed through just fine with the CLI parameters but this one won't.

They actually are distinctly different machines so maybe the specs may shed light.

The one that works:

CPU model	Intel(R) Xeon(R) E-2176G CPU @ 3.70GHz
GPUs	ASPEED Graphics Family, CoffeeLake-S GT2 [UHD Graphics P630]
Core (socket)	12 (1)
Hyper-threading (SMT)	Enabled
Manufacturer info	To Be Filled By O.E.M. (To Be Filled By O.E.M.)
BIOS info	American Megatrends Inc. (P2.70)

af31    0000:00:02.0	Display controller	CoffeeLake-S GT2 [UHD Graphics P630]	
be64   0000:00:17.0	SATA controller	Cannon Lake PCH SATA AHCI Controller	
eb5d   0000:00:1f.0	ISA bridge	Cannon Point-LP LPC Controller	
c25e   0000:00:1f.4	SMBus	Cannon Lake PCH SMBus Controller	
3bb1   0000:00:1f.5	Serial bus controller [0c80]	Cannon Lake PCH SPI Controller	
db2a   0000:00:1f.6	Ethernet controller	Ethernet Connection (7) I219-LM	
ac1a   0000:03:00.0	VGA compatible controller	ASPEED Graphics Family	
3cd2   0000:05:00.0	Ethernet controller	I210 Gigabit Network Connection

The one that doesn't work

CPU model	Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz
GPUs	CometLake-S GT2 [UHD Graphics 630]
Core (socket)	12 (1)
Hyper-threading (SMT)	Enabled
Manufacturer info	Dell Inc. (Precision Tower 3430)
BIOS info	Dell Inc. (1.4.2)

c264   0000:00:02.0	VGA compatible controller	CometLake-S GT2 [UHD Graphics 630]	
6bd6   0000:00:17.0	SATA controller	Cannon Lake PCH SATA AHCI Controller	
e4d6   0000:00:1f.0	ISA bridge	Cannon Point-LP LPC Controller	
7635   0000:00:1f.3	Audio device	Cannon Lake PCH cAVS	
c8ac   0000:00:1f.4	SMBus	Cannon Lake PCH SMBus Controller	
da68   0000:00:1f.5	Serial bus controller [0c80]	Cannon Lake PCH SPI Controller	
01f8   0000:00:1f.6	Ethernet controller	Ethernet Connection (7) I219-LM	
b462  0000:01:00.0	Non-Volatile memory controller	XG6 NVMe SSD Controller	
3b1d  0000:02:00.0	Ethernet controller	NetXtreme BCM5720 Gigabit Ethernet PCIe	
f9e7  0000:02:00.1	Ethernet controller	NetXtreme BCM5720 Gigabit Ethernet PCIe

Interesting things I noted was that on the machine that works:

• there are two GPUs listed there on the working machine (even though it is only the iGPU installed), not sure what ASPEED Graphics Family is
• The working GPU is listed as a Display controller, the not working one is listed as a VGA compatible controller

For now, I will try using xcp-ng center and see if that works for me