Multifunction communication interface supporting memory sharing among data processing systems

In a data processing environment, a communication interface of a second host data processing system receives, from a first host data processing system, a host command in a first command set. The host command specifiesa memory access to a memory coupled to the second host data processing system. The communication interface translates the host command into a command in a different second command set emulating coupling of an attached functional unit to the communication interface. The communication interface presents the second command to a host bus protocol interface of the second host data processing system. Based on receipt of the second command, the host bus protocol interface initiates, on a system fabric of the second host data processing system, a host bus protocol memory access request specifying the memory access.