Interprocessor communication

Interprocessor communication (IPC) is a function that provides communication between processors sharing the same control program. Those executing functions that require a processor or program action on one or more processors use the IPC interface to invoke the desired action. The IPC function uses the signal processor (SIGP) instruction to provide the necessary hardware interface between the processors.

Based on the condition code of the SIGP instruction, the IPC function may invoke the excessive spin routine. The excessive spin routine may cause message IEE331A to be issued. This message either requires the operator to initiate alternate CPU recovery (ACR) or continue with processing. For more information concerning the SIGP instruction, see Principles of Operation.

Remote class services are defined for those control program functions that require the execution of a software function on one of the configured processors. Emergency signal is a remote immediate service that can be invoked via the RISGNL macro.

An emergency-signal external-interruption condition is generated at the specified processor. The interruption condition becomes pending during the execution of the SIGP instruction. The associated interruption occurs when the processor is interruptible for that condition. At any one time the receiving processor can keep pending one emergency-signal condition for each processor of the multiprocessing system, including the receiving processor itself. Issue the RISGNL macro to invoke the emergency signal function.