A mechanism is provided for migrating domains from one physical data processing system to another are provided. Domains may be assigned direct access to physical I/O devices but in the case of migration, the I/O devices may be converted to virtual I/O devices without service interruption. At this point, the domain may he migrated without limitation. Upon completion of the migration process, the domain may be converted back to using direct physical access, if available in the new data processing system to which the domain is migrated. Alternatively, the virtualized access to the I/O devices may continue to be used until the domain is migrated back to the original data processing system. Once migration back to the original data processing system is completed, the access may be converted back to direct access with the original physical I/O devices.