US Patent 7409506 Multiprocessor system with high-speed exclusive control

A multiprocessor system includes a plurality of processors, a shared bus coupled to the plurality of processors, a resource coupled to the shared bus and shared by the plurality of processors, and an exclusive control unit coupled to the plurality of processors and configured to include a lock flag indicative of a locked/unlocked state regarding exclusive use of the resource, wherein the processors include a special purpose register interface coupled to the exclusive control unit, and are configured to access the lock flag by special purpose register access through the special purpose register interface.