Page of GC20-1807-7 As Updated Aug 1, 1979 by TNL GN25-0492
An Overview of VM/370 Commands that Can Be
Used for Debugging
The VM/370 Control Program provides interactive commands that control
the VM/370 system and enable the user to control his virtual machine and
associated control program facilities. The virtual machine operator
using these commands can gather much the same information about his
virtual machine as the operator of a real machine gathers using the
processor console.
Several of these commands (for example, STORE or DISPLAY) examine or
alter virtual storage locations. When CP is in complete control of
virtual storage (as in the case of DOS, MFT, MVT, PCP, CMS, and RSCS) these commands execute as expected. However, when the operating system
in the virtual machine itself manipulates virtual storage (as in the
case of OS/VS1, OS/VS2, or DOS/VS) these CP commands should not be used.
This section presents an overview of the VM/370 commands used for
debugging. It supplements the preceding section which discussed
debugging procedures and techniques. Instructions for using the
commands discussed in this section are in the following publications: • VM/370 CP Command Reference for General Users • VM/370 Operator's Guide • VM/370 CMS Command and Macro Reference
The following categories of commands are discussed: • Commands that display VM/370 control information • Commands that set and query system features, conditions, and events • Commands that collect and analyze system information • Commands that trace events in virtual machines • Commands that alter the contents of storage , COMMANDS THAT DISPLAY OR DUMP VIRTUAL MACHINE DATA Commands that display or dump virtual machine data are: DUMP, VMDUMP, DISPLAY, DCP, and DMCP. The DUMP and DISPLAY commands of CP are privilege class
and are used to display control information describing the
virtual machines.
G commands
status of
The DUMP command spools the following information to your virtual
printer: • Virtual program status word (PSW) • General registers • Floating-point registers • Control reqisters (if your VM/370 directory has the ECMODE option) • Storage keys • Virtual storage locations (first-level storage only) The DISPLAY command displays at your terminal the following kinds of
control information: • Virtual storage locations {first-level storage only} • Storage keys • General registers • Floating-pcint reaisters
36 13M VM/370 System Frograocrner's Guide

Page of GC20-1807-7 As Updated Aug 1, 1979 by TNL GN25-0492 • control registers • Program status word (PSW) • Channel address word (CAW) • Channel status word (CSW) The DCP and DMCP commands of CP are privilege class C and E commands
and are used to display real storage locations. The DMCP command spools
the contents of real storage to your virtual printer. The DCP command
displays at your terminal the contents of real storage locations.
The class G VMDUMP command dumps virtual storage to a specified
reader spool file. VMDUMP provides the same dump information that the DUMP command provides but in a different format. For example, if a tyte of storage contains X'OC', DUMP records it in printable format, X'FOFO'; VMDUMP records it as it appears in storage, X'OO'. The VM/lnteractive Problem Control System Extensions program product can process records
written by VMDUMP. For a description of the format and contents of the VMDUMP records, see "VMDUMP Records: Format and Content" in this
section. COMMANDS THAT SET AND QUERY SYSTEM FEATURES, CONDITIONS, AND EVENTS The SYSTEM and SET commands set system-controlled functions and events;
the QUERY command allows you to determine the status of those settingse
The SYSTEM command is a privilege class G command that simulates the RESET and RESTART buttons on the real computer console. It can also be
used to clear storage.
The functions of the SET command are described in detail in the YlU370 fR f om .!Q3: nd fo£ g.§neral. Qsef:.§. For debugging, the SET command provides the MSG, WNG, and EMSG operands. These provide
messages that may be useful while you are debugging.
The SET MSG function determines whether you receive messages set by
other users via the MSG command. Also, the MSG operand determines
whether you receive messages from CP when other users spool reader,
printer, or punch files to your virtual machine.
The SET SMSG command turns on or off a virtual machines special
message flag. If the virtual machine has issued DIAGNOSE Code X'68'
(Authorize), this flag determines whether the virtual machine accepts or
rejects messages sent via the SMSG command --when the flag is on,
messages are accepted.
The SET WNG function determines whether you receive warning messages
from the system operator.
The
operand
message
specify
spooled SET EMSG function controls error message handling. The EMSG gives you the ability to specify that you want message code,
text, or both to be displayed at your terminal. You can also
that no messages be displayed (except in the case where you have
your console output). When you are debugging, it is useful to have all messages displayed
a t your terminal.
The QUERY command displays the status of features and conditions set
by the SET command for your virtual machine. ON is the default for the MSG, WNG, and EMSG operands of the SET command; OFF is the default for
the SMSG operand. To verify these settings, use the QUERY command. Part 1. Debugging with VM/370 39