I gave sys-gui-gpu a go. I first ran into into the dummy-psu-dom0 → dummy-psu-sender issue above, I guess that has not been release yet.
After patching sys-gui.sls, I ran into the qubes-input-trigger not found errno 2 reported above too.
I fixed that: Fix for no such file error starting sys-gui by face · Pull Request #415 · QubesOS/qubes-core-admin · GitHub. After applying my PR as a patch in dom0, you must restart the qubes manager api: sudo systemctl restart qubesd.service
I then had to disable the gui-vm with qubesctl, delete the VMs, and run the setup again with qubesctl as sys-gui-gpu was not configured properly from not booting during the salt scripts.
Made progress, but now I’m stuck.
sys-gui-gpu is working, and happy, except I cant see it. On sys-gui-gpu’s console, I see lightdm is running via my 2nd Nvidia GPU and nouveau drivers (I have a newer card and the proprietary drivers don’t work with xen but seem to be working with nouveau in sys-gui-gpu which is farther than I got in dom0 with this card).
dom0 still has my intel GPU and control of the monitors. I tried qubes-prefs default_guivm sys-gui-gpu…but dom0 still has the monitors. The setting seems to work for all other VMs and they send their screens to sys-gui-gpu. which I can not see. At one point in all this, I did get a lightdm login screen take over my KDE desktop…but could never reproduce that.
In another thread @fepitre says to log out and run a GuiVM session or run qvm-run -p --no-gui --service sys-gui-gpu qubes.GuiVMSession. The command returns Timed out waiting for Xorg display :1. If I log out , I can’t figure out how to “start a GuiVM session”. I’m running KDE, and sddm has no option. I stopped sddm and started lightdm, but still see no option for a GuiVM session. I don’t see a way or service to start a GuiVM session w/out lightdm or sddm running. Ref: Sys-gui in Qubes 4.1 - devel - #16 by fepitre
It actually makes no sense to me dom0 is still running a DM when lightdm is running on sys-gui-gpu, so I tried changing the runlevel of dom0 to multi-user.target…but dom0 still has the monitors, just a text console instead of a GUI. Note: If I try to give the intel GPU to sys-gui-gpu, insta hard boot of the entire laptop (xen crashes). Then, same crash on boot when sys-gui-gpu starts (I think because dom0 is using it, and xen doens’t like two VMs using the intel GPU at the same time). I can’t figure out how to tell dom0 to give up the GPU and let the sys-gui-gpu take over.