(Alpha and Integrity servers) This parameter is a bitmap
    representing up to 1024 CPUs. Each bit set in this bitmap
    indicates that the corresponding CPU is available for use as a
    Fast Path preferred CPU.

    IO_PRCPU_BITMAP defaults to all bits set. (CPU 0 through CPU 1023
    are all enabled for Fast Path port assignment.)

    You might want to disable the primary CPU from serving as a
    preferred CPU by leaving its bit clear in IO_PRCPU_BITMAP, which
    reserves the primary CPU for non-Fast Path IO operations to use.

    To change the value of IO_PRCPU_BITMAP in SYSBOOT or SYSGEN,
    specify a list of individual bits or contiguous groups of bits.
    For example:

       SYSGEN> SET IO_PRCPU_BITMAP 0,5,17-21

    This command sets bits 0, 5, 17, 18, 19, 20, and 21 in the bitmap
    and clears all other bits.

    Changing the value of IO_PRCPU_BITMAP causes the FASTPATH_SERVER
    process to run the automatic assignment algorithm that spreads
    Fast Path ports evenly among the new set of usable CPUs.

    For additional information, see FAST_PATH and FAST_PATH_PORTS.

    This parameter replaces IO_PREFER_CPU.