A shared memory system includes a plurality of processing nodes and a packetized input/output link. Each of the plurality of processing nodes includes a processing resource and memory. The packetized I/O link operably couples the plurality of processing nodes together. One of the plurality of processing nodes is operably coupled to: initiate coherent memory transactions such that another one of plurality of processing nodes has access to a home memory section of the memory of the one of the plurality of processing nodes; and facilitate transmission of a coherency transaction packet between the memory of the one of the plurality of processing nodes and the another one of the plurality of processing nodes over the packetized I/O link.