Hope this helps AMD64 uses addresses of "canonical form" (see pages 131-135 here) for implementations that do not implement the full 64 bits. The rationale behind this weird scheme is that it is possible to add more bits in the future as hardware evolves, and the two halves will grow together towards the middle. Currently, all implementations (i.e. all existing processors) have 48 bit addresses, thus 00000000'00000000--00007FFF'FFFFFFFF, and FFFF8000'00000000--FFFFFFFF'FFFFFFFF are valid address ranges, with 128TB of memory in each half of the usable address space (256TB total).
AMD OpenCL 2.0 SVM(Shared Virtual Memory) per allocation size and total maximum size
should help you out I experienced similar problem and update to the latest Catalyst (15.7) fixed the problem. Link Also update to the final version of AMD APP SDK v3.0 in case you are still on Beta. Link