ALL traces all instructions, interrupts, successful branches,
privileqe instructions, and virtual machine I/O operations. CSW provides contents of virtual and real channel status words at I/O interrupt.
END terminates all tracinq activity and prints a termination messacre. PRINTER directs tracinq output to PRINTER is specified, RUN is NORUN can be specified.
a virtual spooled printer. If
assumed; however neither RUN nor directs tracing output to the terminal (virtual machine
console). BOTH directs tracing output to both a virtual spooled printer and
the terminal. OFF halts tracing of the specified activities on both the printer
and terminal. RUN stops proqram execution after the trace output to the terminal
and enters the CP command environment. If a Diagnose code X'OOS' is being traced, NORUN has no
effect and program execution does not stop.
continues the program execution after
terminal has completed and does not
environment.
the trace output to the
enter the:P command
1. If vour virtual machine has the virtual=real option and NOTRANS set
on, CP forces CCW translation while tracing either SIO or :CW. When tracing is terminated with the TRACE END command, CCW translation is bypassed again.
2. If hardware assist is enabled on your virtual machine, CP
turns it off while tracing SVC, PRIV, BRANCH, INSTRU:T, or ALL If virtual interval timer support is available on your
processor and is active (that is, SET ASSIST TMR is in effect), CP
turns the timer support off while tracing external interrupts.
After the tracing is terminated with the TRACE END command, CP
turns hardware assist on again.
3. If trace output is beinq recorded at the terminal, the virtual machine stops execution and CP command mode is entered after each
output messaqe. This simulates the instruction step function.
However, all processing associated with "the event being traced is
completej and, therefore, execution may have stopped after an
instruction has executed and the PSW has been updated.
For example, a privileged instruction traced with the PRIV operand stops after the privileged instruction executes, whereas the same
instruction traced with the ALL operand stops before the
instruction executes.
To determine whether the traced instruction has executed, display
the virtual machine PSW. 162 IBM VM/370 CO Command Reference for General Users

TRACE To resume operation of the virtual machine, the BEGIN command must
be entered. If the RUN operand is specified, the virtual machine is
not.stopped after each output message.
4. If trace output is beinq recorded on a virtual spooled printer, a CLOSE command must be issued to that printer output to be printed on the real printer.
., ... • u 5. Successful branches to the next sequential instruction and
branch-to-self instructions are not-detected by TRACE.
6. RUN and RORUN can be specified in different TRACE commands with no
conflict as lonq as the functions being traced are different.
7. Instructions that modify or examine the first two bytes of the next
sequential instruction cause erroneous processing for BR&NCH and INSTRUCT tracinq.
8. When tracing on a virtual machine with only one printer, the trace
data is intermixed with other data sent to the virtual printer. To
separate trace information from other data, define another printer
with a lower virtual address than the previously defined printer. For example, on a system with OOE defined as the only printer,
define a second printer as OOB. The regular output goes to OOE and
the trace output goes to OOB. 9. If the BRANCH, INSTRUCT, or ALL activities are being traced by a virtual machine using a shared system, the user receives a warning
message and the virtual machine is unshared from (given a private
copy of) the named system. Other users of the segment continue to
operate with an unchanged copy of that segment. 10. 110 for virtual channel-to-channel adapters, with both
ends connected to the same virtual machine, cannot be traced. 11. Use the TRACE command to trace specified virtual machine activity
and to record the results at the terminal, at a virtual printer, or
at both. This command is useful in debugging programs because it allows you to trace only the information that pertains to a
particular problem.
12. If your virtual machine is doing I/O that results in
program-controlled interruptions (PCls), and you are tracing I/O or CSW activity, some of the PCls may not be traced. This situation
arises when the system is extending its free storage area and the
additional demand on available free storage could cause a system
abend.
13. The PA1 key on a 3270 display terminal shOUld not be pressed with trace all run active while the display screen indicates status as a subsequent CP command entered from the console may result in interleaved output.
section 5. Format of CP Commands 163