(In reply to Michel Dänzer from comment #63)
> (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?

Primitives aren't reordered with DPBB. Primitives can't also survive a barrier
with DPBB. DPBB has no effect on behavior, it just changes how PS wavefronts
are formed.