Proxmox Got freezed PC when GPU passthrough at PCI-e 16x (PCIEX4)

gerardgarcia

New Member
Mar 25, 2023
13
0
1
Hi there!

I have a Proxmox Server with an AMD Ryzen 7 pro, and a B450 Aorus M motherboard, a Sapphire Pulse RX580 8GB and a Nvidia GT710 1GB.
The motherboard got GPU passthrough successfully on the main PCI-e 16X speed (no matters which GPU I plug there).

But the issue comes when I'm trying to plug a GPU in the second port PCI-e that runs at 4x (PCIEX4).
No matters if I only plug one GPU in that port and nothing connected on the main port.
So, when I try to start a VM, using the GPU plugged on the PCIEX4 port, the computer got freezed instantly.

So the question is, will be a solution to got working GPU passthough on that PCIEX4 port using proxmox?
Or I might to resign to buy another motherboard that have two PCI-e 16X?

This is what Gigabyte manufacturer says about the specs of the mobo:
Expansion Ports:

  1. 1 x PCI Express x16 slot, running at x16 (PCIEX16)
    * Actual support may vary by CPU.
    * For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.
    (The PCIEX16 slot conforms to PCI Express 3.0 standard.)
  2. 1 x PCI Express x16 slot, running at x4 (PCIEX4)
  3. 1 x PCI Express x1 slot
    (The PCIEX4 and PCIEX1 slots conform to PCI Express 2.0 standard.)

Thanks in advance
 
I tried to add pcie_acs_override=downstream,multifunction on etc/default/grub in order to split the IOMMU groups, but, when I do this, the GT710 dissapear from the list. :(
 
So the question is, will be a solution to got working GPU passthough on that PCIEX4 port using proxmox?
Or I might to resign to buy another motherboard that have two PCI-e 16X?
Only the X570 and X570S have proper IOMMU isolation on all PCIe slots and (most) onboard devices. All other AM4 motherboards can only do passthough on the one x16 slot and the one M.2 slot (4 lanes) that use PCIe lanes directly from the CPU (and onboard devices that come from the CPU as well) . All other slots are in one big "chipset IOMMU group". The X470 and X370 can additionally split that x16 slot into two times x8 (which look like x16 for compatibility) that work with passthrough. Sometimes motherboard BIOS versions break passthrough as well.
 
Ok, I
Only the X570 and X570S have proper IOMMU isolation on all PCIe slots and (most) onboard devices. All other AM4 motherboards can only do passthough on the one x16 slot and the one M.2 slot (4 lanes) that use PCIe lanes directly from the CPU (and onboard devices that come from the CPU as well) . All other slots are in one big "chipset IOMMU group". The X470 and X370 can additionally split that x16 slot into two times x8 (which look like x16 for compatibility) that work with passthrough. Sometimes motherboard BIOS versions break passthrough as well



Ok I gonna try that.

As new trying, a few days I bought and PCI Express 2x8 Bifurcator, in order to divide the 16x lane in two 8x lanes and put two graphic cards on the Bus that supposedly work with IOMMU.

I set it up in BIOS, I have video on the RX580, but proxmox system can’t see the GT710.

Then I reboot the server, and plug the display and boot with the GT710.

But in certain way system it’s not freezed at all, but can’t send video to the RX580.

Then I access the proxmox server portal in my mobile, and I notice that in the list of IOMMU Peripherals it’s Empty! I mean it doesn’t detect any IOMMU Periferals.

So, I give up, trying with bifurcator and I gonna try with the x570 or x570s mobo and see what’s happen
 

About

The Proxmox community has been around for many years and offers help and support for Proxmox VE, Proxmox Backup Server, and Proxmox Mail Gateway.
We think our community is one of the best thanks to people like you!

Get your subscription!

The Proxmox team works very hard to make sure you are running the best software and getting stable updates and security enhancements, as well as quick enterprise support. Tens of thousands of happy customers have a Proxmox subscription. Get yours easily in our online shop.

Buy now!