Happened now again when exiting SteamVR. The window was still visible when the system froze.
System report right after reboot: https://gist.github.com/Zamundaaa/839b161f890b50b06f06eb55677239a2
With the latest Mesa and LLVM (maybe Steam, too, idk) updates this doesn't seem to be a problem anymore. I haven't had any hangs for the last few days so I assume this is fixed.
Whelp, so much about that. Just got a freeze again.
I once again haven't had hangs for a while so I guess this can be closed again.
Nothing extracted yet.
System Information (please complete the following information):
Sometimes when starting SteamVR it freezes all graphics on the system, audio apparently still continues playing just fine. The headset does turn on but displays jibberish data, I assume just random patches of GPU memory. After resetting the PC Steam then requires login data again. The crash happens even before any SteamVR window pops up, I basically press "play" in Steam, the launch window appears, disappears and then it hangs.
Note: Commenters who are also experiencing this issue are encouraged to include the "System Information" section in their replies.