OpenCL host library

The API implementations of The OpenCL Runtime and the The OpenCL Platform Layer are compiled to a single dynamic library (e.g., This library contains all implementations and, if pocl is compiled in the ICD mode, is what the ICD loader accesses. In case pocl is instructed (via -DENABLE_ICD=0) to compile a “directly linkable library”, is produced which can be linked directly to the OpenCL programs (instead of linking against the ICD loader).