1. A computer program product for facilitating input/output (I/O) processing of at least one guest processing system, the computer program product comprising: a tangible storage medium readable by a processor and storing instructions for execution by the processor to perform a method comprising: emulating on a native system an I/O architecture for the at least one guest processing system, wherein emulating the I/O architecture comprises: providing multiple device managers, the multiple device managers emulating a plurality of I/O devices of the emulated I/O architecture, wherein the multiple device managers receive I/O command messages of the at least one guest processing system, the I/O command messages being in at least one guest processing system format; providing at least one emulated communications adapter interfacing the multiple device managers to at least one network driver process of the native system external to the emulated I/O architecture, the at least one emulated communications adapter providing a protocol for data transmission from the emulated I/O architecture to the at least one network driver process; and wherein the multiple device managers translate the received I/O command messages in the at least one guest processing system format to messages in native system format and provide the messages in native system format for processing by the at least one emulated communications adapter, thereby facilitating I/O processing of the at least one guest processing system.