I wrote a message to the OpenGL driver forum a while ago about the imageAtomicCompSwap GLSL call (it's part of OpenGl 4.2 and previously was the EXT_shader_image_load_store extension) being defective on all ATI GPUs that I have available, i.e., HD 50000- HD 7000 cards (http://www.opengl.org/discussion_boards/showthread.php/178148-imageAtomicCompSwap-not-working-on-AMD...). Since problem appears to be neither OS related nor specific to a single GPU generation I assume it's a driver bug (or a very stable hardware bug, that's present in multiple generations of GPUs). Unfortunately, the OpenGL.org post did not invoke any response from AMD (only from a couple of other developers that can reproduce the issue), filing a detailed bug report with AMDs including short demo code to demonstrate the issue did not result in any response either (neither a fix nor any response whatsoever). Having no idea what to do now I post this here in the hopes that some AMD employe might eventually read this and find some time to respond. Even if this would be hard/impossible to fix or be very low priority I think it would help to get some idea about a possible timeframe.