XXX: new device tree management
The address parameter is used to uniquely identify the device on the ISA bus. For example, if there are two identical NE2000 cards plugged into the machine, the address will be be the only way the host OS can distinguish them, because all of the other parameters of the device will be identical. If address is in the range 0-0xffff (0-65535), it is interpreted as a port number in I/O space; otherwise, it is interpreted as a physical memory address. For devices that use any I/O ports for communication with software, the base of the ``primary'' range of I/O ports used by the device should be used as the address; a physical memory address should be used only for devices that only communicate through memory-mapped I/O.