Problem
Type
Abend
Unexpected
Results
Wait
Loop
Where
Abend Occurs CP abend
CMS abend
Virtual
machine
abend (other
than CMS)
CP
Virtual
machine
CP LOADER RSCS
CP disabled
loop
Virtual
machine dis­
abled loop
Virtual
machine ena­
bled loop
Figure 61. VM/SP Problem Types
Distinguishing Characteristics
For a complete discussion of reasons for abends and system pro­
grammer's actions, see the CP and CMS abend codes charts in
VM/SP System Messages and Codes.
When OS or DOS abnormally terminates on a virtual machine, the
messages issued and the dumps taken are the same as they would be if OS or DOS abnormally terminated on a real machine.
VM/SP may terminate or reset a virtual machine if a nonrecoverable
channel check or machine check occurs in that virtual machine. One of the following messages:
DMKMCH616I MACHINE CHECK; USER userid TERMINATED
DMKCCH604I CHANNEL ERROR; DEV xxx; USER
userid; MACHINE RESET
is sent to the system operator at the processor console. Also, the vir­
tual user is notified by one of the following messages that his virtual
machine was terminated or reset:
DMKMCH619I MACHINE CHECK; OPERATION TERMINATED
DMKCCH606I CHANNEL ERROR; OPERATION TERMINATED
If an operating system, other than CMS, executes properly on a real
machine, but not properly with CP, a problem exists. Inaccurate data
on disk or system files (such as spool files) is an error.
If a program executes properly under the control of a particular oper­
ating system on a real machine, but does not execute correctly under
the same operating system with VM/SP, a problem exists.
For a complete discussion of CP, loader, and RSCS wait state codes,
see VM/SP System Messages and Codes.
The processor console wait light is off. The problem state bit of the
real PSW is off. No I/O interrupts are accepted.
The program is taking longer to execute than anticipated. Signaling
attention from the disabled loop terminal does not cause an interrupt
in the virtual machine. The virtual machine operator cannot commu­
nicate with the virtual machine's operating system by signalling atten­
tion.
Excessive processing time is often an indication of a loop. Use the
CP QUERY TIME command to check the elapsed processing time.
In CMS, the continued typing of the blip characters indicates that
processing time is elapsing. If time has elapsed, periodically display
the virtual PSW and check the instruction address. If the same
instruction, or series of instructions, continues to appear in the PSW,
a loop probably exists.
Introduction to Debugging 471

Is there an ABEND condition? If the message DMKDMP9081 SYSTEM FAI LURE, CODE XXXXXX appears on
the console and the alarm rings, this is a CP ABEND. The system dumps to disk
or to the printer if the set dump E
command has been issued, automatically performs IPL. If the messages DMKDMP9081 SYSTEM Y FAI LURE CODE XXXXXX DMKCKP9601 SYSTEM WARMSTART DATA SAVED
DMKCKP961W SYSTEM SHUTDOWN COMPLETE appear on the console, this is
a CP ABEND. The system dumps to or printer and stops. Pi V If the message DMSABN148T SYSTEM I!:B ABEND XXX, CALLED FROM YYYYYY
appears on the terminal, this is a CMS ABEND. 50 R If an ABEND message from the virtual iii machine appears on the terminal, this is
an ABEND in the operating controlling this virtual machine. R Otherwise, an ABEND condition does not exist. GO TO Does a problem exist?
START DEBUGGING No problem exists
Unexpected Results? f!iR1llf an operating system which executes liY:iJ properly on a real machine fails to execute
Figure 62. Does a Problem Exist? properly under VM/SP, there are unexpected results in CPo .. If a program which executes under the control of an operating system on a real machine fails to execute correctly with
the same operating system under VM/SP
there are unexpected results in the I5:l virtual machine. lt r;;:;;J If the program's output is inaccurate or r!::!.] missing, there are unexpected results in
the problem program. If the output is redundant check
for a Fall Otherwise, check for a wait or loop . ........... 472 VM/SP System Programmer's Guide
Excessive time has elapsed. If pressing the REQUEST key on the EY3 operator's console leaves the REQUEST PENDING light on, a CP disabled wait will be on.- .. 4A
state exists. The CPU console light If the CPU console wait light is on system is in a CP enabled wait state. If the real PSW problem bit is OFF, r4':l there is a CP loop. .. 0 r:rlr If any of the following messages DMKDSP450W CP ENTERED; DISABLED WAIT PSW, DMKDSP451W CP ENTERED; INVALID PSW,
DMKDSP452W CP ENTERED;
EXTERNAL INTERRUPT LOOP DMKPRG453W CP ENTERED; PROGRAM INTERRUPT LOOP appears on the terminal, there is a disabled wait or an interrupt loop f4::l in the virtual machine. .. rm If pressing the ATTN key once does not IlY cause an interrupt, there is loop in the virtual machine. . If processing has ceased in the virtual machine without reaching end of job,
the virtual machine is in an enabled wait state and no I/O interrupt has occurred. [61 If processing time exceeds normal expectations the virtual may have an enabled loop. . V 1m Otherwise,