Method and apparatus for shared I/O in a load/store fabric

An apparatus for associating packets in a load/store serial communication fabric with root complexes to allow the root complexes to share an input/output (I/O) endpoint, the apparatus comprising:

• a shared I/O switch, coupled to each of the root complexes, said shared I/O switch having routing control to associate the packets from each of the root complexes with the root complex they originate from by incorporating a field within the packets;
• and
• a link between said shared I/O switch and the input/output (I/O) endpoint, wherein said link allows the packets to be transferred from said shared I/O switch to the input/output (I/O) endpoint with said field;
• wherein the input/output (I/O) endpoint associates the packets with their associated root complexes by examining said field.

A method for associating packets, within a serial load/store fabric, from a plurality of root complexes with their originating root complex, to allow the plurality of root complexes to share an I/O endpoint, the method comprising:

• providing a first link between the plurality of root complexes and a switch, the packets in the first link unaware that the root complexes are sharing the I/O endpoint;
• within the switch, embedding a header in the packets to associate the packets with their originating root complex;
• providing a second link between the switch and the I/O endpoint, the second link capable of communicating the packets with the embedded header between the switch and the I/O endpoint;
• and
• at the I/O endpoint, examining the packets with the embedded header to allow the I/O endpoint to associate each of the packets with their originating root complex.

A method for partitioning I/O devices among a plurality of processing complexes, the partitioning performed within the load/store domain of each of the processing complexes, the method comprising:

• providing a switch between the I/O devices and the plurality of processing complexes, the switch utilizing a first load/store fabric between the plurality of processing complexes and the switch, and a second load/store fabric between the switch and the I/O devices;
• mapping each of the plurality of processing complexes to one or more of the I/O devices;
• and
• transferring packets between the plurality of processing complexes to the I/O devices based upon said mapping;
• wherein at least one of the I/O devices is mapped to only one of the plurality of processing complexes;
• and
• wherein at least one of the I/O devices is mapped to two or more of the plurality of processing complexes.