Patent attributes
A method and apparatus are described for facilitating proper ordering of peer-to-peer communications between bridged bus segments. According to one embodiment of the present invention a fence command is issued when a peer-to-peer communication between devices on separate bus segments connected on the same side of a bridge is detected. The fence command is inserted into a plurality of buffers in an I/O hub corresponding to the bus segments to force temporary ordering across all pipes of the I/O hub. The hub prohibits processing of subsequent commands from a buffer once a fence command has been read from that buffer until a corresponding fence command is read from all other buffers in the plurality of buffers therby assuring proper ordering of the peer-to-peer communication.