from m5 import build_envfrom m5.params import *from m5.proxy import *from MemObject import MemObjectif build_env['FULL_SYSTEM']:    from Device import BadAddrclass Bus(MemObject):    type = 'Bus'    port = VectorPort("vector port for connecting devices")    bus_id = Param.Int(0, "blah")    clock = Param.Clock("1GHz", "bus clock speed")    header_cycles = Param.Int(1, "cycles of overhead per transaction")    width = Param.Int(64, "bus width (bytes)")    responder_set = Param.Bool(False, "Did the user specify a default responder.")    block_size = Param.Int(64, "The default block size if one isn't set by a device attached to the bus.")    if build_env['FULL_SYSTEM']:        responder = BadAddr(pio_addr=0x0, pio_latency="1ps")        default = Port(Self.responder.pio, "Default port for requests that aren't handled by a device.")    else:        default = Port("Default port for requests that aren't handled by a device.")