These results can be reproduced on all driver versions across Linux and Windows. The situation hasn't improved at all since the first drivers with OpenGL 4.2 "support" were released.
|Core Profile||Compatibility Profile|
Arguably the most important function for modern shading techniques, imageAtomicCompSwap doesn't work on any combination of profile or platform.
Drivers making wrong claims about supported functionality is actually worse for application developers than if the functionality wasn't implemented at all, because programs end up relying on broken functionality advertised by the drivers.
Previous discussion on opengl.org: http://www.opengl.org/discussion_boa...12-6?p=1241539