I discovered another scenario where the games launch properly…
- Moved the DP cable to a side DP port (one driven by the iGPU)
- Set KDE settings display orientation so the laptop was on the left (mouse flows properly between displays; matches the physical layout)
- rem’d my extra lines in
/usr/share/sddm/scripts/Xsetupsince I knew they were not needed with the DP monitor on iGPU … that SDDM would load across both monitors without it. - rebooted
- launched the games and they behaved properly?! good, but confused why
This scenario kinda suggests that when the dGPU port is used to drive a display, it wants to be on the left? And that’s basically the same as scenario one, except set to the left in the KDE settings with the monitor plugged directly to the dGPU.
Might this be an amdgpu bug, or issue with the dGPU?
------- Update -------
I got curious and wondered what would happen if I added a step 6… swapping the kde orientation settings so the DP was set to be on the left of the laptop again (keeping it physically right)… no problems!
I think it is also important to note that this is while booted into a KDE X11 session. If I log out and launch KDE wayland the “windowed” game behaves properly, but a fullscreen game crashes xwayland… and so I stick to x11 where my game at least all launch.
------- Update 2 -------
I think I figured out another important detail… some steam games have a native linux version whereas many require PROTON to allow windows games to run on Linux. The two games focused on in my writings were not Linux native games, so PROTON / VULKAN / etc is involved. Launched a 3rd windowed game that has a Linux native version, and it launched/behaved properly.