DMKIOFVR -- parameter reflection, record the error. DMKSVC, REFSVCB ---aEFSVCB--Is-ca11ed if TRACE SVC was in effect or if the virtual
machine's page zero is not in real storage. Obtains the system lock
before continuing. If the system lock is not immediately available, REFSVCB defers the interrupt and exits to DMKDSPRU. DMKTRCSV module is called if TRACE SVC was invoked. DMKPRGRF is not active, flag user as being in instruction wait
state and reflect the SVC back to the user. DMKSVC ---rf-the virtual machine's page zero is in real storage. generate and
store an old SVC PSi. Fetch the new SVC PSi. If there is no PSi state
change, store user's new PSi in RUNPSi, restore registers and
dispatch via LPSi. DMKSVC, REFSVCA there-Is a PSi state change, obtain the system lock before
continuing. If the system lock is not immediately available, defer
the interrupt and exit to DMKDSPRU. DMKDSPB ---Check the altered PSi. SVC INTERRUPTIONS - SUPERVISOR STATE Entry is for a system failure and is a SVC 0 or SVC 4 abend
condition. DMKDMPDK ---perform partial or full real storage dump. DMKCKPT ---Checkpoint the system. DMKCPINT ---perform an automatic IPL if indicated. DMKSVC, SVCLINK 8 provides linkage to a called routine in R15. DMKPTRUL routine is not resident, page it in and return control to
the caller by loading the SAVERTN into the old PSi and then load the
old PSi. The caller's addressabi1ity, SAVEAREA address and return
address are maintained in a new SAVEAREA. QMKSVC, Entry via SVC 12 return control from the called routine to the
calling routine and restores addressabi1ity via R12 and R13. DMKPTRUL module, unlock page to return it to DISD. Entry via SVC 16 to release the current SAVEAREA used by SVC 8 and Return to caller. DMKSVC, SVCGET via-SVC 20 to obtain a new SAVEAREA. Return to caller. Entry via SVC 24 to switch control to the main processor. EXTERNAL AND CLOCK INTERRUPTION REFLECTION DMKPSAEX via the interruption key on system console, adjust accounting
to charge for supervisor overhead. If problem Bode, attention
interruption, update the virtual machine PSi from the external old PSi. 1-184 IBM VM/370 System Logic and Problem Deteraination--Voluae 1

DMKPSA, Exit to dispatcher, if there is no logged-on operator, or the
operator is disconnected, or there is no active terminal. If the
operator was logged on and the external interruption key was pressed,
disconnect the operator's terminal.
DKKQCNCL
Clear all console requests. DMKSCNRD ----If-the device is a terminal or graphic device, issue HIO to the real
device. DMKDSPCH the dispatcher. QKKPSA, For 3704/3705, convert resource identifier for the NCP terminal for
the indexable entry into the NICBLOK for the associated VMBLOK, then
DMKRNHND ---aeset all BTUs. DMKDSPCH - Exit-to the dispatcher. !2MKPSA, Upon location X'80' timer interruption, indicate the user end of the time slice by storing flag in the VMBLOK's VKOSTAT. If the system lock is held or is available, exit to the main entry of
the dispatcher, DMKDSPCH. Otherwise, exit to DKKDSPRU. Upon processor timer interruption, VMTLEVEL in VKBLOK as a real
processor timer interruption. DMKTKRVT ---Simulate the interruption. If the system lock is held or is available, exit to the .ain entry of
the dispatcher, DMKDSPCH. Otherwise, exit to DMKDSPRU. DMKPSA, EXTCKC ---Upon clock-comparator interruption reflection Use the printer to unchain the active TRQBLOK. Call DMKSTKIO. DMKSTKIO ---Stack the block. DMKDSPCH, DMKDSPRU system-lock is held or is available, exit to the main entry of
the dispatcher, DMKDSPCH. Otherwise, exit to DMKDSPRU. MONITOR INTERRUPTION PROCESSING DMKKOR VM Monitor data collection component uses both sample and trace
techniques. Selected system counters are sampled by routines entered
periodically via TRQBLOK •. Selected events are traced upon execution
via monitor call instructions embedded at strategic points in the
control program. DMKMORTI ---riQBLOK gives control here every 60 seconds (unless specified
otherwise with the MONITOR INTERVAL command), and a new TRQBLOK is immediately stacked via call to DMKSCHST, to request a return to the same entry point 60 seconds later. Control register 8 monitor mask is used to determine which of the three sampled data classes (PERFORM, USER, DASTAP) are enabled. Appropriate counters are
sa.pled using special subroutines for each class and the data is
stored in the monitor buffers. Upon completion, goes to dispatcher. CP Method of Operation and Program Organization 1-185