Created attachment 254909 [details]
Xorg and kernel logs

Hi all,

with Linux 4.10 I still have a problem I already had with at least 4.8: On my MacBook Pro 8.2 (aka "early 2011") with Intel IGD and AMD Radeon discrete GPU, using the Radeon (not switching to IGD with vga_switcheroo before) causes Xorg not to start. Somewhere I had found this mentioned in some discussion, together with a hint to revert commit 4eebd5a4e72697aac25a8a57d3f888a9d5f80370 ("apple-gmux: lock iGP IO to protect from vgaarb changes"), which helps.
I seem to remember there was a mention of some kind of deadlock somewhere in the DRM infrastructure that thread, causing not only Xorg to hang, but also making it impossible to access any gpu-driven console. It is possible to do a regular shutdown via ACPI powerbutton though.

I had hoped this would somehow get resolved by the people on that thread, but obviously, it didn't.

I'm attaching some Xorg and kernel logs of both working and non-working states. The kernel logs both(!) contain a warning about a possible circular locking dependency where vgaswitcheroo tries to acquire a lock it already holds. The "4.10.0" logs are from the non-working, hanging state, while the "4.10.0-00001-gdf6ffb763137" logs are from the working state running 4.10.0 with the mentioned commit reverted.