Non native display resolution with Intel UHD Graphics 630 graphics passthorugh (max 2048x1080 instead of 2560x1440)

[emma.makes]

I'm currently in the trial phase with Unraid and set up a VM with Intel UHD Graphics 630 pass-through for the graphics. The connected display has a native resolution of 2560x1440, but the VM only allows setting a resolution of 2048x1080. I've tested the behavior with Fedora 36 and Xubuntu 22.04.

 

Is there anything I can attempt to allow the VM to set 2560x1440 resolution? Is this due to the virtualization limitation or a problem of the VM guest OS?

[ghost82]

Hi, look at this, it doesn't seem related to vm settings.

https://unix.stackexchange.com/questions/547812/how-to-enable-2560x1440-option-for-display-in-linux-mint

 

Look at the xrandr output and see what are available resolutions and max.

Check your monitor EDID, decode it, and see if 2560x1440 is available in the EDID.

Check also the refresh rate (frequency) when you set the new resolution, this depends on the monitor, gpu, cable and resolution.

Edited May 30, 2022 by ghost82

[emma.makes]

7 hours ago, ghost82 said:

Hi, look at this, it doesn't seem related to vm settings.

https://unix.stackexchange.com/questions/547812/how-to-enable-2560x1440-option-for-display-in-linux-mint

 

Look at the xrandr output and see what are available resolutions and max.

Check your monitor EDID, decode it, and see if 2560x1440 is available in the EDID.

Check also the refresh rate (frequency) when you set the new resolution, this depends on the monitor, gpu, cable and resolution.

Thank you for the feedback. I'll have to try and manually force the resolution, but this behavior does not occur, if I boot (e.g. Fedora 36) without Unraid KVM.

I've had similar issues with Ubuntu and Debian, which seemed like an issue related with an older kernel version, while Fedora with a newer kernel automatically picked up the correct resolution of the monitor. So maybe this is related to the kernel version used by the Unraid Slackware base?

[ghost82]

8 minutes ago, emma.makes said:

So maybe this is related to the kernel version used by the Unraid Slackware base?

I don't think so, because when you passthrough a (i)gpu to a guest all should be managed by the guest and the kernel of the host should have no impact.

By "passing through the igpu" you mean gvt-d with a monitor connected to the vga output directly or something else?

Edited May 30, 2022 by ghost82

[emma.makes]

1 hour ago, ghost82 said:

I don't think so, because when you passthrough a (i)gpu to a guest all should be managed by the guest and the kernel of the host should have no impact.

By "passing through the igpu" you mean gvt-d with a monitor connected to the vga output directly or something else?

Oh okay, interesting! I wasn't aware of that.

 

I'm not sure what you mean by gvt-d. I've set the VMs Graphics Card to "Intel UHD Graphics 630 (00:02.0)" (the only option I have other than VNC) and no "Graphics ROM BIOS". The monitor is directly connected via HDMI on the monitor to Display Port on the HP ProDesk (Display Port to HDMI cable). If I boot Fedora on the HP ProDesk, without Unraid, it detects the correct resolution.

 

If it's relevant, machine is set to Q35-6.2 and BIOS to OVMF.

 

 

[ghost82]

9 minutes ago, emma.makes said:

I'm not sure what you mean by gvt-d. I've set the VMs Graphics Card to "Intel UHD Graphics 630 (00:02.0)"

That's gvt-d, direct access, lucky you that works

I have no explanation for the resolution, sorry, I would try to add it manually.

 

PS: can you share your xml for that vm, or even better diagnostics?Another user is struggling to make his uhd630 passthrough without success...

Edited May 30, 2022 by ghost82

[emma.makes]

7 minutes ago, ghost82 said:

That's gvt-d, direct access, lucky you that works

I have no explanation for the resolution, sorry, I would try to add it manually.

 

PS: can you share your xml for that vm, or even better diagnostics?Another user is struggling to make his uhd630 passthrough without success...

 

Thanks, I'll give it a try!

Honestly, I'm really surprised myself, that the iGPU passthrough works so smoothly. I've previously attempted to achieve the same with Proxmox and failed.

 

I've replaced the UUIDs and the MAC address in the config, let me know if I can help out in any other way. The host is a HP ProDesk 400 G5 Mini (https://support.hp.com/us-en/document/c06403257, with an i5-9500T CPU). Unraid is the latest stable (6.10.2) via the USB installer, VM client is a Fedora 36 netinst/everything. I've set up the VM with basically all the default settings, except the Graphics Card.

vm.txt