I had an older install of Qubes 4.1 on another SSD, pre Xen 4.14.1 to be precise. I recalled that at some point I could start sys-gui-gpu and so I tried again yesterday. The template was still fedora-32-xfce, everything like in the first thread opened by @panati last year:
Thanks to the information trickeling in bits and pieces from here and there I think I know a little more (not much) on how this is supposed to work.
I disabled sys-gui and enabled sys-gui-gpu.
I tried attaching my 2nd GPU via qubesctl state.sls qvm.sys-gui-gpu-attach-gpu like explained in the documentation draft. This selected 00:02.0 PCI (...) Processor root port which I think isn’t the right choice. I got an error message regarding a “non-ending pci device (…)”. I don’t know what to make of it but I read that the whole sys-gui-gpu is meant to be working out of the box for Intel rather than AMD graphics. So I looked at the list of pci-devices in my sys-gui-gpu app.
My 2nd GPU is listed as a display controller for my Radeon HD 8570. 01:00.0 Display Controller: Advanced Micro Devices, Inc. [AMD/ATI] Sun PRO [Radeon HD 8570A/8570M]
I selected this one and my laptop froze immediately after applying and restarting sys-gui-gpu. I read that this is expected and a reboot might be needed.
I restarted and my autostart-apps are booting up including sys-gui-gpu.
Now I am asking myself how I can check if things are working as they should?
First of all, might this be the right choice for my 2nd GPU. (It looked right to me but what do I know?)
Do I have to specifically assign selected or all apps to the sys-gui-gpu as guiVM like with sys-gui?
Something like qvm-prefs work guivm sys-gui-gpu ?