[SOLVED] Proxmox GPU passthrough - I can’t see the VM GPU output on the Proxmox monitor

[titust11]

I configured GPU passthrough in Proxmox, and a VM to use the PCIe GPU. The VM is set to boot at startup. I don’t want to access the VM remotely, and I was expecting to see the VM’s GPU output directly on the Proxmox monitor.
It works but with an annoying workaround.
The only way to achieve this, is to unplug the monitor cable, during Proxmox startup, and plug it back when the VM is up, then I can see the VM‘s GPU output on Proxmox server monitor. This is what I want to achieve.
If I don’t unplug the monitor during Proxmox boot, I see the blue grub screen briefly, then a black screen and it stops sending signal to the monitor.
The VM boots OK but the video output from the VM is not sent to the monitor anymore.
This unplugging and plugging back the monitor cable is annoying each time I have to reboot the server.

Any ideas to avoid this? A workaround?
thanks a lot

 

[Pifouney]

Hey,

(Hum ... not really need an answer, but need to explain ... Why use Windows + Passthough GPU for not using the dedicated GPU ? xD)

Can you post you VM configuration here ? screenshot or cat of your vmID.conf

thanks

 

[titust11]

agent: 1
bios: ovmf
boot: order=virtio0;ide2;net0;sata0
cores: 8
cpu: host
efidisk0: VMs:100/vm-100-disk-1.raw,efitype=4m,pre-enrolled-keys=1,size=528K
hostpci0: 0000:01:00,pcie=1,x-vga=1
ide2: local:iso/Win11_English_x64v1.iso,media=cdrom
machine: pc-q35-6.1
memory: 10240
meta: creation-qemu=6.1.1,ctime=1644877715
name: Windows11
net0: virtio=A2:9D:E2:24:A3:A3,bridge=vmbr0,firewall=1
numa: 0
onboot: 1
ostype: win11
sata0: local:iso/virtio-win-0.1.215.iso,media=cdrom,size=528322K
scsihw: virtio-scsi-pci
smbios1: uuid=8ffa55f4-507a-4040-b66f-6e144bea90be
sockets: 1
tpmstate0: VMs:100/vm-100-disk-2.raw,size=4M,version=v2.0
usb0: host=046d:c52b,usb3=1
virtio0: VMs:100/vm-100-disk-0.raw,size=64G
vmgenid: 8bef3f29-cb98-4ca5-86f4-a0eb39c8107f

 

[titust11]

Follow up on the above discussion.....
I thought my issue was caused the VM OS Windows11, so I created a Ubuntu VM. I have the same video output / cable problem. I tried then disabling completely the Integrated Graphics in the BIOS. I have the same problem.
I see two possibilities, either there is something wrong in the way I implemented passthrough (although I used the Promox step by step), or I should have installed Proxmox using the Integrated Graphics then disable it and switch to the PCIe GPU. I'm pooling my hair.
Anyone in the same situation?

 

[Pifouney]

You need to add a logical screen, for your kinf of use.

 

[titust11]

I’ve never hear of a logical screen, what do you mean by that? and how you do this?

 

[titust11]

You need to add a logical screen, for your kinf of use.

A brief search in google about “logical screen” returns nothing.

 

[titust11]

Here is the reason I had this behavior and the fix:
- There was an error in the grub file

GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt pcie_acs_override=downstream,multifunction nofb nomodeset video=vesafb:off,efifb:off"

This parameter video=vesafb:off,efifb:off the way it is written here was causing the problem. The line should be like this
GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt pcie_acs_override=downstream,multifunction nofb nomodeset video=efifb:off video=vesafb:off"

 

[yharby]

Here is the reason I had this behavior and the fix:
- There was an error in the grub file

This parameter video=vesafb:off,efifb:off the way it is written here was causing the problem. The line should be like this
GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt pcie_acs_override=downstream,multifunction nofb nomodeset video=efifb:off video=vesafb:off"

Thank you this helped me also with RX 580 4GB

 

[titust11]

I'm glad it worked for you too. Have you ever been able to pass through an iGPU? (Intel in my case)

 

[yharby]

I'm glad it worked for you too. Have you ever been able to pass through an iGPU? (Intel in my case)

Not tried yet, I will try and give feedback

 

[yharby]

You figured out how to share audio with VM?

 

[titust11]

You figured out how to share audio with VM?

I didn’t reach that point of testing audio, but I think you have to passthrough the audio controller of the mtb

 

[leechy00]

You figured out how to share audio with VM?

Guessing here: Back in the Hardware screen when you add the GPU as a PCI Device, make sure you check "All Functions"... maybe it brings the audio too then.

 

[semanticbeeng]

... don’t want to access the VM remotely, and I was expecting to see the VM’s GPU output directly on the Proxmox monitor.

So using this kernel command in the proxmox host line really achieves this?

GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt pcie_acs_override=downstream,multifunction nofb nomodeset video=efifb:off video=vesafb:off"

Asking in context of another question: https://forum.proxmox.com/threads/perfect-developer-desktop.133437/post-620594