On Alpha and Integrity server systems, allows a process to map
    a section of its address space to a specified physical address
    range represented by page frame numbers. This service creates and
    maps a private page frame section.

    This service accepts 64-bit addresses.

    Format

      SYS$CRMPSC_PFN_64  region_id_64 ,start_pfn ,page_count ,acmode

                         ,flags ,return_va_64 ,return_length_64

                         [,start_va_64]

    C Prototype

      int sys$crmpsc_pfn_64  (struct _generic_64 *region_id_64,

                             unsigned int start_pfn, unsigned

                             int page_count, unsigned int

                             acmode, unsigned int flags, void

                             *(*(return_va_64)), unsigned __int64

                             *return_length_64,...);