The main objective is to provide a unique API to map a device
        resource whatever the bus.
        Of course for VME devices the implementation is for the time being,
        highly dependant of the PCI/VME_BRIDGE implementation. There is an on
        going initiative at CERN to expose VME device like PCI device resource
        file.
        Currently CERN_VME_BRIDGE is supported, but only activated through
        a condiational compile statement (see Makefile).
Signed-off-by: Michel Arruat <michel.arruat@cern.ch>