I Signaling I SIGNAL Macro IPUADDR CPU address of this processor IPUADDRX CPU address of the other processor
The system uses this information for interprocessor communication.
During certain critical periods, such as when a processor malfunctions or when a
processor synchronization must occurs, one processor must signal the other
processor. There are three types of program-controlled signals possible under VM/SP. They are:
Emergency signals
Direct signals
External call signals Use the SIGNAL macro to issue the signal processor (SIGP) instruction. If you
have generated the system as an AP IMP system, the control program expands the
macro. The macro expansion code destroys the contents of registers 0, 1, 14, and
15. The macro expansion loads register 0 with the signalled processor address,
loads register 1 with the function code, and uses registers 14 and 15 for linkage.
Note: If you have not generated the system as an AP IMP system, the control pro­
gram treats the SIGNAL macro as a no-operation.
The SIGNAL macro causes all signaling requests to be sent to the external inter­
ruption handler so that error analysis and recovery attempts are centralized.
The format of the SIGNAL macro and the functions that you can perform using
each type of signal are:
label SIGNAL CLKCHK , [
,CONTROL=SERIAL]
EXTEND
QUIESCE SHUTDOWN SYNC
XTNDEXIT 1------- -----------------------
APR
[
,CONTROL=[PARALLEL]]
DISPATCH = AUTO RESUME WAKEUP :-------- ----------------------
RESTART
[
,CONTROL=[PARALLEL]]
START = AUTO STOP \ SSS
where:
label
is any desired label.
CP in Attached Processor and Multiprocessor Modes 211
is the function to be performed and is a required positional parameter. This
parameter can be an emergency signal, an external call signal, or a direct
signal.
Emergency Signals
When one processor wants the other processor to perform an action imme­
diately, it executes an emergency signal instruction. Since emergency signals
can only be serial, control is not returned to the issuing processor until the oth­
er processor pericrms the function. The emergency signals are:
CLKCHK -indicates that the high order bits of the time-of-day clocks are not
synchronized
EXTEND -indicates that free storage extend processing is to take place
QUIESCE -indicates that the receiving processor is to halt all execution until a
RESUME signal is received SHUTDOWN - indicates that the system is about to shutdown
SYNC -indicates that the low order bits of the time of day clocks are no long­
er synchronized
XTNDEXIT -indicates that free storage extend process is complete and virtual
machines can be dispatched again
External Call Signals
When one processor wants to call the other processor's attention to an event or
condition, it executes an external call order. The external call functions are:
APR -causes automatic processor recovery to be invoked to attempt to remove
a failing processor from the configuration
DISPATCH -indicates that a CPEXBLOX is on the dispatcher's queue for the
receiving processor
RESUME -cancels a previous QUIESCE signal
WAKEUP -indicates that the processor is to resume operations after having
stopped processing
Direct Signals
212 VM/SP System Programmer's Guide
Direct signals correspond to physical buttons on the real processor. These
signals are controlled by the hardware, and cannot be masked off. The direct
signals are: RESTART, START, STOP, and SSS (stop and store status). CONTROL= is the second operand. CONTROL=SERIAL - specifies that control returns to the sender
after the function is complete. CONTROL=SERIAL is the only
parameter that you can use with the emergency signals. You cannot
specify CONTROL=SERIAL for the external calls and direct signals.
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