Thanks a lot for the links. The smp_processor_id returns the CPU ID on which the current process is running. This is required to maintain the process affinity. In the driver on which I am working the code checks to see if the last interrupt was received on the current cpu. And based on this decision further processing is done. On interrupt: last_intr_cpu = store the current CPU id In some other function if (current CPU ID = last_intr_cpu) _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.