DMSITP, the CMS program interrupt handler, issues error messages when a
program check occurs. If aSPIE or a ST AE has been issued, control is passed
to the specified routine; otherwise control passes to DMSABN to attempt to
recover from the error. If the message DMSITP144T is issued, theUFDBUSY byte is not zero and control is halted after the message is typed. If the wait
state bit is turned off in thePSW, control continues as above. Also, if the error
occurred during the execution of a system routine, control is halted until the
wait state bit is turned off orCMS is re-IPLed.
To determine the registers andPSW at the time of the abend, get the address
of PGMSECT in the nucleus constant area(NUCON X'654'). The old PSW is
stored 12 (X'C') bytes into the DSECT, immediately followed by registers 14,15,0, 1, and 2. The program interrupt element (PIE), needed by SPIE, prima
rily uses these areas. Registers0 through 15 are stored at location X'3 C' into
the DSECT. TheSPIE/ST AE routine or the DMSSAR routine uses the other
areas within the DSECT.
Another aid to debugging is theSVC save area (SVCSA VE) for the virtual
machine. Location X'528' inNUCON points to these areas. The save areas
are easily recognizable by the check words 'ABCD' and 'EFGH' contained
within them. The address of theSVC caller is stored at location 4 and the
name of the routine being called is saved at location 8. At locationX'10', the
oldPSW is stored, followed by the addresses for the normal return and the
error return. The registers0 through 15 are stored at location X'20', followed
by the floating point register atX'60'. After the first check word ('ABCD'),
the address of the nextSVCSAVE area is stored, followed by the address of
the previousSVCSAVE area and the address of the user's area. If the address
of the next or previousSVCSAVE area is zero, the chain is terminated.
Debugging With eMS 535
program check occurs. If a
to the specified routine; otherwise control passes to DMSABN to attempt to
recover from the error. If the message DMSITP144T is issued, the
state bit is turned off in the
occurred during the execution of a system routine, control is halted until the
wait state bit is turned off or
To determine the registers and
of PGMSECT in the nucleus constant area
stored 12 (X'C') bytes into the DSECT, immediately followed by registers 14,
rily uses these areas. Registers
the DSECT. The
areas within the DSECT.
Another aid to debugging is the
machine. Location X'528' in
are easily recognizable by the check words 'ABCD' and 'EFGH' contained
within them. The address of the
name of the routine being called is saved at location 8. At location
old
error return. The registers
by the floating point register at
the address of the next
the previous
of the next or previous
Debugging With eMS 535
