The fix by AMD's Michel Dänzer has the Radeon Gallium3D winsys store GPU virtual memory addresses of buffer objects in a hash table. This change fixes problems with XWayland when using the RadeonSI GCN driver in conjunction with xf86-video-wlglamor, the XWayland DDX that uses GLAMOR for 2D acceleration when running X11 applications/games in a Wayland-based environment.
If you're an affected XWayland user the fix is in the latest Mesa code.
On a separate note, there's still been no communication if XWayland will attempt to be mainlined for the X.Org Server 1.16 release this summer, but at least there continues to be progress in porting various high profile software components to run on Wayland natively... SDL 2.0.2 was recently released with the Wayland back-end, Ozone-Wayland is working well for Chromium, Enlightenment is making progress to become its own Wayland compositor, KDE is making progress, and GNOME 3.12 made more Wayland improvements though it's still to be considered a preview future.
Stay tuned for more of the latest on Wayland and open-source Linux graphics developments at Phoronix.