Page of GC20-1807-7 As Updated April 1, 1981 by TNt GN25-0829 Ii Is there an ABEND condition? II If the message DMKDMP9081 SYSTEM FAILURE, COOE XXX XXX
appears on the console and I the alarm rings,
this is a CP ABEND.
The svstem dumps to disk or to the
printer if the set dump E command
has been issued, and automaticallv performs IPL. • V II If the messages DMKDMP9081 SYSTEM FAILURE, COOE XXXXXX DMKCKP9601 SYSTEM WARMSTART DATA SAVED DMKCKP961W SYSTEM SHUTDOWN COMPLETE
appear on the console,
this is a CP ABEND.
The system dumps to tape !l!' p!inte, .nd stops. - C5J II If the message DMSABNI48T SYSTEM ABEND XXX, CALLE!;) FROM YYYYYY appears on the terminal, this is a CMS ABEND.-C51 II If an ABEND message
from the virtual machine appears
on the terminal, START DEBUGGING ,_,w,_ __________ ...... I. has elapsed II If pressing the REOUEST key on the operator's
console leaves the REOUEST PENDING light on,
a CP disabled wait state exists.
The CPU console light will be on. --- C5J II If the CPU oonscle wait light is on,
the system is in a CP enabled wait state. II If the real PSW problem bit is OFF, f4;l there is a CP loop. ---_ .... II If anv of the following messages . DMKDSP450W CP ENTERED; DISABLED WAIT PSW DMKDSP451W CP ENTERED; INVALID PSW DMKDSP452W CP ENTERED; EXTERNAL INTERRUPT LOOP
DMKPRG453W Ci' ENTERED; PROGRAM INTERRUPT LOOP appears on the terminal,
there i. a disabled wait or an interrupt loop in the
this is an ABEND in the No problem exists
virtual machine. -------__ '\ operating svstem controlling this virtual machine._C5J II Otherwise, an ABEND
condition does not exist, I Fiqure ____________________ 0) 3. fI Unexpected Results? II If an operating system which
executes properly on a real machine
fails to execute properlv under VM/370, there are unexpected results r--"""\ inCP. • l5
A
J II
I! a program which executes under V the control of an operating svstem on
a real machine fails to execute correctly with the same operating svstem under VM/370, there are unexpected results rs;l in the virtual machine. V II
I! the program's output is Inaccurate or miSSIng, there are unexpected results
in the problem program. If the output is redundant r-::'\ check for a loop. - 0 II check for a wait or o Does a Problem Exist? II
I! preSSing the ATTN key once does not cause an mterrupt, V there is a disabled loop in the virtual machine. ) II
I! processing has ceased in the virtual machine without reaching end-of·job, the virtual machine is in an GJ enabled wait state and no 1/0 interrupt has ocwrred. li
lt processing time exceeds normal expectations,
the virtual machine mav have an enabled loop. ) Part 1. Debugging with VM/370 15

Fiqure
April 1, 1981
Debug Procedures for a Wait
4.
CP Disabled Wait • • Use AL TER/DISPLAY console mode (if available), to display real PSW and CSW. Also, display general and extended control registers and storage locations X·OO·-X·l00·. Press SYSTEM RESTART button to cause a CP ABEND
dump to be taken. IPL. CP Enabled Wait --------------------------------4 • Press SYSTEM RESTART button to cause a
CP ABEND dump to be taken.
Use the dump to check the status of each VMBLOK. Also, check RCHBLOK. RCUBLOK. and RDEVBLOK for each device. Virtual Machine Disabled Wait --------------------------1 • Use CP commands (CMS users may use the CMS DEBUG command) to display
the PSW, CSW, general registers, and control registers.
Use the CP DUMP command (or CMS DUMP subcommand) to
take a dump. Virtual Machine Enabled Wait --------------------------/
Take adump.
Debug Procedures for a Loop • • Use ALTER/DISPLAY console mode (if available) tei
display real PSW, general registers. control registers, and storage locations X·OO·-X·l00·. Press SYSTEM RESTART button to cause a CP
ABEND dump to be taken.
Examine the CP internal trace table to see where the loop is. Virtual Machine Disabled Loop --------------------------1 • • • Use the CP TRACE command to trace the loop.
Display the general registers and control llegisters via the CP DrSPLA Y command.
Take a dump using the CP DUMP command.
Examine the source code. Virtual Machine Enabled Loop --------------------------1
Trace the loop. Display the PSW, general registers,
and extended control registers. • Take a dump. • Examine source code.
Debug Procedures for Waits and Loops
16 IBM VM/J70 System programmer's Guide