(In reply to pavol from comment #4) > I do not have radeonsi supported device. How does Intel driver support this? > I think this is really useful for picking algorithm. The piglit test tests/spec/glsl-1.50/execution/primitive-id-no-gs.shader_test is for this very case. That test passes at least on my Ivybridge. I don't know what we do in the driver to make this work... or if the hardware just sorts it out.