I tested 0001-nvkm_gpuobj-size-is-smaller-then-nvkm_gpuobj-size-ca.patch with
4.9.0-rc7 and it correctly initializes the console at 3840x2160 @ 30Hz (for
some reason, the 60Hz mode is not detected).

I also tried the patch on top of drm-next (which as of today is still based on
4.9.0-rc5), but all I got a blank screen. This branch has other stability
issues, so it's not necessarily a nouveau regression.

With 4.9.0-rc7, I can start Xorg, but xf86-video-nouveau fails to initialize:

 [   336.771] (II) [drm] nouveau interface version: 1.3.1
 [   336.771] (EE) Unknown chipset: NV124

This is expected, since GM20x acceleration landed after
xf86-video-nouveau-1.0.13. I'll try rebuilding from head and report back.