(In reply to Diego Viola from comment #62)
> export MESA_EXTENSION_OVERRIDE="-GL_NV_texture_barrier"
> 
> This helps alleviate the problem (xterm does not have the issue with this),
> however, the problem is still present in Xephyr.

To clarify, you mean Xephyr from xserver 1.16 here (where glamor didn't make
use of GL_NV_texture_barrier yet), disabling GL_NV_texture_barrier helps with
current Xephyr, right?

It seems like DPBB needs to be disabled when glTextureBarrier(NV) is called,
otherwise primitives may be reordered across the barrier. Does that make sense,
Marek?