$IO_FASTPATHW_

   On Alpha and Integrity server systems, performs operations on the
   set of Fast Path devices and CPUs enabled for Fast Path use.

   The $IO_FASTPATHW system service is functionally equivalent to
   the $IO_FASTPATH service except that it completes synchronously.
   That is, it returns after the operation is complete.

   Format

     SYS$IO_FASTPATHW  efn, cpu_mask, function_code, [iosb],

                       [astadr], [astprm], [,[mask_length]]

   C Prototype

     int sys$io_fastpathw  (unsigned int efn, UINT32_PQ cpu_mask,

                           int function_code, struct_iosb *iosb,

                           void (*astadr)(_ _unknown_params),

                           _ _int64 astprm, ...) ;)