Just to clarify there are certain OpenCL extensions which are features that a GPU might provide that is outside of the specification for OpenCL. The one required by the Help Conquer Cancer GPU application is cl_khr_local_int32_base_atomics. If you get this error it means that your GPU does not provide this feature therefore the code will exit in the beginning. I have not found a good site from the vendors which specifies which extensions each of their cards provides. At the beginning of the HCC GPU run information for the GPU to be run on is output and one of the things it lists is all the extensions. This list can be found in the stderr after the tag "CL_DEVICE_EXTENSIONS:". On our end we need to go through the list of cards producing this error and exclude them from receiving work. Unfortunately for the HCC GPU work this extension is required.

Thanks,
armstrdj