1. An apparatus for transferring data in a load/store fabric between a plurality of root complexes and a shared input/output (I/O) endpoint, the apparatus comprising: an interface configured to receive a packet from at least one of the plurality root complexes, the packet including a header field for identifying the shared I/O endpoint for which the packet is destined, said interface coupled to the plurality of root complexes, wherein in lieu of including a controller within each of the root complexes for transferring data to the shared I/O endpoint, the plurality of root complexes are coupled to said interface to share the endpoint; and circuitry configured to: add an operating system domain (OSD) header field to the packet for identifying which one of the plurality of root complexes is associated with the packet; and transfer the packet with the added OSD header field to the shared endpoint.