I run windows as a VM and pass my GPU though, the pass through bit is working, the performance however is not what I was expecting, in fact its crap, I mean no better than GTX1070. The fps is all over the place there are very large lags spikes even in older games like subnautica which shouldn’t tax a RX6800 even at 1440p. The system shock remake with vsync off can’t manage more than 60fps at any detail level and the gpu barely pulls more than 75watts. Running furmark it’ll happily pull more than 200watts so I know its not power delivery. I also know its not poor disk performance. In the Radeon windows drivers the card is reported to be running at PCI-E Gen 4 x1 rather than x16, now I know nvidia cards report lower pci-e gen usage when idle so I'm going to assume AMD's do too, however when applying a load like a game you'd expect it to be running at gen 4 x16,
kernel: 6.3.11-200.fc38.x86_64
I should note everything is set correctly in the bios too, no bifurcation of the x16 slot
I also have a Radeon WX2100 is running as pci-e gen 3 x1 has the amdgpu driver accidentally configured my RX6800 to use a single lane or am I barking mad? The RX6800 is using vfio-pci as its kernel driver. I know the drivers in windows are able to read the PCI-E widths and speeds, as my old 1070 would display as PCi-E 3.0 x16.
I'm unable to know whether it worked in earlier versions of the kernel as this is a new piece of hardware. Is there anyway to verify which pci-e mode the card is actually running in rather than just its capability?
System Specs:
Ryzen 5900X
32GB ECC RAM
Gigabyte Aorus X570 Pro
Radeon RX6800 [Guest Passthrough GPU] (in main PCI-E x16, PCI-E slot 1)
Radeon WX2100 [Host GPU] (in PCI-E x1 PCI-E slot 3) This card is set as the first display in the bios so it displays post
Random PCI-E Usb card (Guest Passthrough)
Adata SX8200 ssd in the main m.2 slot.