Displays a stack trace.
Syntax |
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TR[ACE] [level] [options]
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The TR command produces a trace of the procedures active on the current PIN's stack. The command is mode sensitive. If the user is in cmdebug, a trace of the compatibility mode stack is produced, if in nmdebug, a trace of the native mode stack is printed. An interleaved stack trace of both CM and NM stacks is produced by using the DUAL option.
If the current stack is the NM interrupt control stack (ICS), when
the base of the ICS is reached, System Debug automatically switches
to the stack of the last running process and continues the stack
trace. This feature in no way implies that the routines on the ICS
were invoked on behalf of the last running process.
If the dispatcher is currently running, there is no last
running process, so the stack trace stops when the base of the ICS
is found.
Parameters |
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- level
The desired maximum depth for the stack trace. If level is omitted, the entire depth of the stack is traced.
- options
Any combination of the following options may be specified:
- DUAL
Display both NM and CM stack markers, interleaved across switch markers.
- SINGLE
Display a single stack marker at the specified level.
- UNWIND
Display formatted stack unwind descriptor information.
- FULL
Display a fully detailed stack trace.
- ISM
Trace across interrupt markers.
NM Examples |
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$nmdebug > tr
PC=115.00005b50 processstudent.highscore
* 0) SP=40221180 RP=115.00005f0c processstudent+$1e8
1) SP=40221180 RP=115.00006b1c PROGRAM+$300
2) SP=40221100 RP=115.00000000
(end of NM stack)
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Display an entire NM stack trace. The first line indicates the address the PC register points to. Each stack level is formatted, starting from the top of stack and working down the depth of the stack. Level numbers are indicated on the left; an asterisk marks the current level. (Refer to the LEV command.)
$nmdebug > tr
PC=a.0074da24 FWRITE
* 0) SP=40221260 RP=a.00748150 ?FWRITE+$8
export stub: f4.0012d044 P_FLUSHLINE+$54
1) SP=40221260 RP=f4.00139560 P_WRITELN+$20
2) SP=40221200 RP=f4.00139630 P_WRITELN+$9c
3) SP=402211c8 RP=f4.0013950c ?P_WRITELN+$8
export stub: 115.00005e30 processstudent+$10c
4) SP=40221180 RP=115.00006b1c PROGRAM+$300
5) SP=40221100 RP=115.00000000
(end of NM stack)
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The above example shows a stack trace that contains a call from the
program file to a user library, and from the user library to the system
NL. Transitions between libraries are performed through the use of
export stubs. (Refer to the Procedure Calling Conventions Reference Manual (09740-90015) for a description of export stubs.)
$nmdebug > tr,unw
PC=115.00005b50 processstudent.highscore
* 0) SP=40221180 RP=115.00005f0c processstudent+$1e8
Can't Unwind: 0 Entry-FR: 00 Call_FR: 00 Region: Normal
Millicode: 0 Entry-GR: 00 Call_GR: 00 Frame-size: 6 (dbl words)
Large-Frame-R3: 0 Save-SRs: 00 Save-SP: 0 Save-MRP: 0
Save-SR0: 0 Cleanup: 0 Save-RP: 0 Args-stored: 1
Interrupt-Mrkr: 0
1) SP=40221180 RP=115.00006b1c PROGRAM+$300
Can't Unwind: 0 Entry-FR: 00 Call_FR: 00 Region: Normal
Millicode: 0 Entry-GR: 03 Call_GR: 00 Frame-size: 10 (dbl words)
Large-Frame-R3: 0 Save-SRs: 00 Save-SP: 1 Save-MRP: 0
Save-SR0: 0 Cleanup: 0 Save-RP: 1 Args-stored: 1
Interrupt-Mrkr: 0
2) SP=40221100 RP=115.00000000
Can't Unwind: 0 Entry-FR: 00 Call_FR: 00 Region: Normal
Millicode: 0 Entry-GR: 00 Call_GR: 00 Frame-size: c (dbl words)
Large-Frame-R3: 0 Save-SRs: 00 Save-SP: 1 Save-MRP: 0
Save-SR0: 0 Cleanup: 0 Save-RP: 1 Args-stored: 0
Interrupt-Mrkr: 0
(end of NM stack)
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Native mode stack trace relies on the presence of unwind descriptors as
produced by the language compilers. Without these information
blocks, a stack trace would not be possible. The UNWIND option
is used to display the unwind descriptor associated with each procedure.
(Refer to the Procedure Calling Conventions Reference Manual (09740-90015) for a description of unwind descriptors.)
$nmdebug > tr,f
PC=a.0074da24 NL.PUB.SYS/FWRITE
* 0) SP=40221260 RP=a.00748150 ?FWRITE+$8
DP=c0200008 PSP=40221260 PCPRIV=0
export stub:
f4.0012d044 XL.PUB.SYS/P_FLUSHLINE+$54
1) SP=40221260 RP=f4.00139560 P_WRITELN+$20
DP=40200648 PSP=40221200 PCPRIV=3
2) SP=40221200 RP=f4.00139630 P_WRITELN+$9c
DP=40200648 PSP=402211c8 PCPRIV=3
3) SP=402211c8 RP=f4.0013950c ?P_WRITELN+$8
DP=40200648 PSP=40221180 PCPRIV=3
export stub: 115.00005e30 GRADES.DEMO.TELESUP/processstudent+$10c
4) SP=40221180 RP=115.00006b1c PROGRAM+$300
DP=40200008 PSP=40221100 PCPRIV=3
5) SP=40221100 RP=115.00000000
DP=40200008 PS
P=402210a0 PCPRIV=3
(end of NM stack)
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A FULL stack trace displays the value of DP, PSP and the privilege level (0-3 for each level in the stack).
$nmdebug > tr 2,single
2) SP=40221200 RP=f4.00139630 P_WRITELN+$9c
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Display only stack level 2.
$nmdebug > tr
PC=a.006777fc trap_handler
* 0) SP=40221338 RP=a.002a1fec conditional+$ac
1) SP=40221338 RP=a.000a5040 hpe_interrupt_marker_stub
--- Interrupt Marker
$nmdebug > tr,ism
PC=a.006777fc trap_handler
* 0) SP=40221338 RP=a.002a1fec conditional+$ac
1) SP=40221338 RP=a.000a5040 hpe_interrupt_marker_stub
--- Interrupt Marker
2) SP=402211e8 RP=25d.00015134 small_divisor+$8
--- End Interrupt Marker Frame ---
PC=25d.00015134 small_divisor+$8
0) SP=402211e8 RP=25d.00015d38 average+$b0
1) SP=402211e8 RP=25d.00015c74 ?average+$8
export stub: 25c.00005d98 processstudent+$74
2) SP=40221180 RP=25c.00006b1c PROGRAM+$300
3) SP=40221100 RP=25c.00000000
(end of NM stack)
$nmdebug >
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In the above example, the first stack trace encounters an interrupt marker and stops tracing. The second stack trace uses the ISM option to continue tracing past the interrupt marker. The interrupt that caused the interrupt marker to be generated was caused by a divide by zero in the small_divisor routine.
CM Examples |
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%cmdebug > tr
PROG % 0.1421 PROCESSSTUDENT+14 (mITroc CCG) SEG'
* 0) PROG % 0.2004 PROCESSSTUDENT+377 (mITroc CCG) SEG'
1) PROG % 0.253 OB'+253 (mITroc CCG) SEG'
2) SYS % 25.0 ?TERMINATE (MItroc CCG) CMSWITCH
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Display a CM stack trace. The first line indicates the address
CMPC points to. Each stack marker is formatted, starting from the top of stack and working down the depth of the stack. Level numbers are indicated on the left; an asterisk marks the current level.
(Refer to the LEV command.)
%cmdebug > tr,f
PROG % 0.1421 PROCESSSTUDENT+14 (CSTX 1) SEG'
X=22750 P=1421 Status=(mITroc CCG 301) DeltaQ=13670
* 0) PROG % 0.2004 PROCESSSTUDENT+377 (CSTX 1) SEG'
X=6 P=2004 Status=(mITroc CCG 301) DeltaQ=14
1) PROG % 0.253 OB'+253 (CSTX 1) SEG'
X=36 P=253 Status=(mITroc CCG 301) DeltaQ=10
2) SYS % 25.0 ?TERMINATE (CST 26) CMSWITCH
X=0 P=0 Status=(MItroc CCG 026) DeltaQ=4
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The above examples specifies the FULL option to display
the value of the X, P, and status registers, and the DELTA-Q value.
Translated Code Examples |
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Break at: NM [1] TRANS 24.00854ea4 PASCAL'LIBRARY2:?P'WRITESTR
$nmdebug > tr ,dual
PC=24.00854ea4 PASCAL'LIBRARY2:?P'WRITESTR
NM* 0) SP=40221290 RP=a.0067320c outer_block+$e8
NM 1) SP=402210a0 RP=a.00000000 inx_A0000+$14
(end of NM stack)
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The above example shows Debug stopping at a breakpoint. The breakpoint
was set in SL.PUB.SYS at the entry point to the P'WRITESTR
routine. Since the system SL is translated, Debug set two breakpoints
(one in the CM emulated code and one in the translated NM code). The
NM translated code breakpoint is encountered, and so Debug stops.
A stack trace reveals that the process is indeed stopped at the entry point to P'WRITESTR, but no other recognizable markers appear. This is because translated code does not actually switch to CM mode, so
no switch markers exist to enable the DUAL option to
function. However, the CM stack is maintained as if the code were being run by the emulator. Switching to cmdebug and performing a stack trace reveals this.
$nmdebug > cm
%cmdebug > tr
SYS % 36.15626 ?P'WRITESTR (mITroc CCG) PASCAL'LIBRARY2
* 0) PROG % 0.1737 PROCESSSTUDENT+%332 (mITroc CCG) SEG'
1) PROG % 0.253 OB'+%253 (mITroc CCG) SEG'
2) SYS % 25.0 ?TERMINATE (MItroc CCG) CMSWITCH
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The above trace shows all of the CM procedures that are active on the
stack. Remember, the CM stack is maintained even if the code is running
translated.
Dual Mode Examples |
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$nmdat > tr,d
PC=a.000a4838 enable_int+$20
NM* 0) SP=40201ce0 RP=a.0013cdf0 notify_dispatcher.block_current_process+$294
NM 1) SP=40201ce0 RP=a.0013deec notify_dispatcher+$34c
NM 2) SP=40201c88 RP=a.001dc964 wait_for_active_port+$ec
NM 3) SP=40201c10 RP=a.001dd680 receive_from_port+$450
NM 4) SP=40201bc0 RP=a.00228514 extend_receive+$4d8
NM 5) SP=40201b28 RP=a.00218bdc rendezvousio.get_specific+$194
NM 6) SP=40201a78 RP=a.00218ec8 rendezvousio+$13c
NM 7) SP=40201a08 RP=a.0020f274 attachio.perform_io+$f8
NM 8) SP=402018c8 RP=a.00210414 attachio.terminal_functions+$fac
NM 9) SP=40201838 RP=a.00214d40 attachio+$2e4
NM a) SP=402017e0 RP=a.0020e3bc ?attachio+$8
export stub: a.003e30e4 arg_regs+$28
NM b) SP=402015c8 RP=a.0044db34 nm_switch_code+$f30
NM c) SP=40201498 RP=a.000a09b0 cm_swtnm_call+$8
(switch marker frame)
CM SYS % 27.253 SWITCH'TO'NM'+%4 (Mitroc CCG) SUSER1
CM * 0) SYS % 27.253 SWITCH'TO'NM'+%4 (Mitroc CCG) SUSER1
CM 1) SYS % 25.7765 ATTACHIO+%325 (Mitroc CCG) CMSWITCH
CM 2) SYS % 22.17700 DEALLOCATE+%30 (Mitroc CCG) XLSEG11
CM 3) SYS % 3.5540 F'CLOSE'+%4321 (MitroC CCG) FSSEG3
CM 4) switch marker (Mitroc CCG)
NM d) SP=40201208 RP=a.000a07bc ?CM_SWITCH+$30
export stub: a.0044c3e4 switch_to_cm+$c30
NM e) SP=40201018 RP=a.006f3c84 fclose_nm+$74c
NM f) SP=40200db0 RP=a.006e62a8 FCLOSE+$368
NM 10) SP=40200aa8 RP=a.0036a0b0 fs_proc_term+$a4
NM 11) SP=40200a00 RP=a.00197550 terminate_process+$318
NM 12) SP=40200948 RP=a.00326fb0 TERMINATE+$28
NM 13) SP=40200668 RP=a.00326a2c ?TERMINATE+$8
export stub: a.003e30e4 arg_regs+$28
NM 14) SP=40200638 RP=a.0044db34 nm_switch_code+$f30
NM 15) SP=40200508 RP=a.000a09b0 cm_swtnm_call+$8
(switch marker frame)
CM 5) SYS % 27.253 SWITCH'TO'NM'+%4 (MITroc CCG) SUSER1
CM 6) SYS % 25.5 TERMINATE+%5 (MITroc CCG) CMSWITCH
CM 7) PROG % 0.244 (mITroc CCE)
CM 10) SYS % 25.0 ?TERMINATE (MItroc CCG) CMSWITCH
NM 16) SP=40200278 RP=a.0030d868 outer_block+$144
NM 17) SP=40200088 RP=a.00000000
(end of NM stack)
$nmdat >
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The above example shows an interleaved NM and CM stack trace.
Limitations, Restrictions |
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The DUAL option is ignored if the current mode is not the same as the original entry mode. (Refer to the ENV ENTRY_MODE command.)
When CM code has been translated, it is not possible to obtain dual
mode stack traces. The NM and CM stacks may be traced individually, however.
People debugging the operating system need to be aware of the following
limitation. If an interrupt handler is running that has interrupted code running in CM mode, dual stack trace is incorrect. In addition, not all of the CM stack may be shown.
Native mode stack trace depends on the presence and accuracy of
unwind descriptors in the program file and libraries to trace stacks.
If these descriptors are not present, corrupted, or not correctly sorted,
System Debug may produce incorrect stack traces.
DAT is only able to trace the part of the NM stack that corresponds to
code in NL.PUB.SYS. If by chance the unwind descriptors of the
code that called the NL routines are resident, the stacked procedure
calls are displayed all the way to the base of the stack. The
names of the procedures in other libraries and program files are not
known to DAT.
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 | CAUTION: The output format of all System Debug commands is subject to change
without notice. Programs that are developed to postprocess
System Debug output should not depend on the exact format (spacing,
alignment, number of lines, uppercase or lowercase, or spelling) of
any System Debug command output. |
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