4. Consult the source code to search for the faulty instructions, exam1n1ng previously executed modules if necessary. Begin by
scanning for instructions that set the condition code or branch en
it.
5. If the manner of loop entry is still undetermined. assume that a
wild branch has occurred and begin a search for its origin. WAIT No processing occurs in the virtual machine when it is in a wait state. When the wait state is an enabled one, an I/O interrupt causes
processing to resume. Likewise
r when the Contrel Program is in a wait
state, its processing ceases.
A disabled wait state usually results from a hardware malfunction.
During the 1PL process; normally correctable hardware errors may cause a
wait state because the operating system error recovery procedures are
not accessible at this point. These conditions are recorded in the
current PSW. CP may be in an enabled wait state with channel 0 disabled when it is
attempting to acquire more free storage. Examine EC register 2 to see
whether or not the multiplexer channel is disabled. A severe .achine
check could also cause a CP disabled wait state.
Three types of severe machine checks can cause the Control
Program to terminate or cause a CP disabled wait state. • An unrecoverable machine check in the control program • A machine check that cannot be diagnosed • Timing facilities damage A machine check error cannot be diagnosed if either the machine check
old PSi or the machine check interrupt code is invalid. These severe
machine checks cause the control program to terminate.
If a severe machine check or channel check caused a CP disabled wait
state, one of the following messages will appear: CHANNEL ERROR, RUN SEREP, RESTART SYSTEM MACHINE CHECK TIMING FACILITIES tAMAGE; RUN SEREP DMKMCT612i MACHINE CHECK TIMING FACILITIES DAMAGE; RUN SEREP Part 1. Debugging with VM/370 27

If an unrecoverable machine check occurs in the control program, the message DMKMCH610W MACHINE CHECK SUPERVISOR DAMAGE --or-- DMKMCT610i MACHINE CHECK SUPERVISOR DAMAGE appears on the processor console. The control program is terminated and
enters a wait state 001 or wait state 013. If the machine check handler cannot diagnose a certain machine check,
the integrity of the system is The message DMKMCH611i MACHINE CHECK SYSTEM INTEGRITY LeST --or-- DMKMCT611i MACHINE CHECK SYSTEM INTEGRITY LOST appears on the processor console. The control program is terminated and
enters wait state 001 or wait state 013. Hardware errors are probably the cause of these severe machine checks. The system operator should run the CPEREP program and save the
output for the installation hardware maintenance personnel.
If the generated system cannot run on the real machine because of
insufficient storage, CP enters the disabled wait state with code OOD in
the PSi. The insufficient storage condition occurs if: • The generated system is larger than the real machine size
--or-- • A hardware malfunction occurs which reduces the available amount of
real storage to less than that required by the generated system The message DMKCPI955i INSUFFICIENT STORAGE FOR VM/370 appears on the processor console.
If CP cannot continue because consecutive hardware errors are
occurring on one or more V8/310 paging devices, the message D8KPAG415E CONTINUOUS PAGING ERRORS FROM DASD xxx appears on the processor console and CP enters the disabled wait state
with code OOF in the PSi. If more than one paging device is available, disable the device cn
which the hardware errors are occurring and IPt the system again. If
the VM/370 system is encountering hardware errors on its only paging
device, move the paging volume to another physical device and IPL again.
Bote: This error condition may occur if the VM/370 paging volume was not properly formatted. 28 IB!