lib/mpi/generic_mpi-asm-defs.h - linux - Git at Google

 /* This file defines some basic constants for the MPI machinery.  We
  * need to define the types on a per-CPU basis, so it is done with
  * this file here.  */
 #define BYTES_PER_MPI_LIMB  (SIZEOF_UNSIGNED_LONG)
	/* This file defines some basic constants for the MPI machinery. We
	* need to define the types on a per-CPU basis, so it is done with
	* this file here. */
	#define BYTES_PER_MPI_LIMB (SIZEOF_UNSIGNED_LONG)