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April 1986

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Document:	VAX/VMS System Dump Analyzer Reference Manual
Order Number:	AA-Z429C-TE
Revision:	000
Pages:	132
Original Filename:	https://archive.org/download/stx_AA-Z429C-TE_VMS_4.4_VAX_VMS_System_Dump_Analyzer_Reference_Manual_Apr86/AA-Z429C-TE_VMS_4.4_VAX_VMS_System_Dump_Analyzer_Reference_Manual_Apr86.pdf

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VAX/VMS
System Dump Analyzer
Reference Manual
Order Number: AA-Z429C-TE

April 1986

This document explains the use of the System Dump Analyzer (SDA) to
analyze the running system and dumps of system failures.

Revision/Update Information:

This document supersedes the
VAX/VMS System Dump Analyzer
Reference Manual Version 4.2.

Software Version:

VAX/VMS Version 4.4

digital equipment corporation
maynard, massachusetts

April 1986

The information in this document is subject to change without notice and should
not be construed as a commitment by Digital Equipment Corporation. Digital
Equipment Corporation assumes no responsibility for any errors that may appear
in this document.
The software described in this document is furnished under a license and may be
used or copied only in accordance with the terms of such license.
No responsibility is assumed for the use or reliability of software on equipment
that Is not supplied by Digital Equipment Corporation or its affiliated companies.
Copyright ©1986 by Digital Equipment Corporation
All Rights Reserved.
Printed in U.S.A.
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System Dump Analyzer Contents
PREFACE

vii

NEW AND CHANGED FEATURES

FORMAT

SDA-1

COMMAND SUMMARY

SDA-2

DESCRIPTION

SDA-4

INTRODUCTION TO SDA

SDA-5

SYSTEM MANAGEMENT AND SDA

SDA-5

2.1

The System Dump File

SDA-5

2.2

Setting the Size of the Dump File

SDA-6

2.3

Saving System Dump Files

SDA-6

2.4

The System Startup Procedure

SDA-7

USING SDA

SDA-8

3.1

Analyzing a System Dump

SDA-8

READING THE SYSTEM DUMP FILE

SDA-9

ANALYZING A RUNNING SYSTEM

SDA-9

5.1

Building the SDA Symbol Table

SDA-10

SDA COMMAND FORMAT

SDA-10

6.1

General Command Format

SDA-10

6.2

Expressions

SDA-11

6.2.1

Radix Operators

SDA-11

6.2.2

Arithmetic and Logical Operators

SDA-12

6.2.3

Precedence Operators

SDA-12

6.2.4

Symbols

SDA-13

iii

System Dump Analyzer Contents

ANALYZING SYSTEM FAILURES

SDA-14

7.1

General Procedure for Analyzing System Failures

SDA-14

7.2

Fatal Bugcheck Conditions

SDA-15

7.2.1

Fatal Exceptions

SDA-15

7.2.2

Illegal Page Faults

SDA-19

A SAMPLE SYSTEM FAILURE

SDA-20

8.1

Identifying the Bugcheck

SDA-20

8.2

Identifying the Exception

SDA-20

8.3

Locating the Source of the Exception

SDA-22

8.3.1
8.3.2

8.4

8.5

Finding the Driver by Using the Program
Counter

SDA-22

Calculating the Offset into the Driver's Program
Section

SDA-23

Finding the Problem Within the Routine

SDA-23

8.4.1

Examining the Routine

SDA-24

8.4.2

Checking the Values of Key Variables

SDA-25

8.4.3

Identifying and Fixing the Defective Code

SDA-25

Inducing a System Failure

COMMANDS

SDA-26

SDA-30

@ {EXECUTE PROCEDURE)

SDA-31

ATTACH

SDA-32

COPY

SDA-33

DEFINE

SDA-34

EVALUATE

SDA-38

EXAMINE

SDA-41

EXIT

SDA-45

FORMAT

SDA-46

HELP

SDA-48

READ

SDA-49

REPEAT

SDA-51

SDA-52

System Dump Analyzer Contents

SET LOG

SDA-54

SET NOLOG

SDA-55

SET OUTPUT

SDA-56

SET PROCESS

SDA-58

SET RMS

SDA-60

SHOW CLUSTER

SDA-64

SHOW CONNECTIONS

SDA-68

SHOW CRASH

SDA-70

SHOW DEVICE

SDA-73

SHOW HEADER

SDA-78

SHOW LOCK

SDA-79

SHOW PAGE_TABLE

SDA-80

SHOW PFN_DATA

SDA-84

SHOW POOL

SDA-87

SHOW PORTS

SDA-89

SHOW PROCESS

SDA-90

SHOW RESOURCE

SDA-98

SHOW RMS

SDA-102

SHOW RSPID

SDA-103

SHOW STACK

SDA-105

SHOW SUMMARY

SDA-107

SHOW SYMBOL

SDA-109

SPAWN

SDA-110

VALIDATE QUEUE

SDA-112

INDEX

System Dump Analyzer Contents

FIGURES

SDA-1

An Argument List on the Stack

SDA-17

SDA-2

The First Argument List on the Stack

SDA-17

SDA-3

A Mechanism Array

SDA-17

SDA-4

A Signal Array

SDA-18

SDA-5

The Stack Following an Illegal Page-Fault Error

SDA-19

Preface
Intended Audience
This document is for users who need to debug device drivers or other system
code.

Structure of This Document
This document is composed of three major sections.
The Format Section is an overview of SDA and is intended as a quick
reference guide. The format summary contains the DCL commands that
invoke SDA, listing all qualifiers and parameters. The usage summary
describes invoking and exiting from SDA, how to direct output, and any
restrictions you should be aware of. The command summary lists all of the
SDA commands.
The Description Section explains how to use SDA.
The Commands Section describes each of the SDA commands and the
qualifiers and parameters used with each. The commands appear in
alphabetical order.

Conventions Used in This Document
Convention

Meaning
A symbol with a 1- to 3-character abbreviation
indicates that you press a key on the terminal, for
example, |RET| .
The phrase CTRL/x indicates that you must press
the key labeled CTRL while you simultaneously
press another key, for example, CTRL/C, CTRL/Y,
CTRL/0.

$ SHOW TIME
05-JUN-1985 11:55:22

The command examples show all output lines
or prompting characters that the system prints
or displays in black letters. All user-entered
commands are shown In red letters.

$ TYPE MYFILE.DAT

A vertical series of periods, or vertical ellipsis,
means either that not all the data normally
displayed by the system in response to the
particular command is shown or that not all the
data a user would enter is shown.

file-spec,...

A horizontal ellipsis indicates that additional
parameters, values, or information can be entered.

VII

Preface

vlii

Convention

Meaning

[logical-name]

The square brackets indicate that the enclosed
item is optional. (Square brackets are not,
however, optional In the syntax of a directory name
in a file specification or In the syntax of a substring
specification In an assignment statement.)

quotation marks
apostrophes

The term quotation marks refers refer to double
quotation marks ("). The term apostrophe (')
refers to a single quotation mark.

New and Changed Features
The following new commands have been added to the System Dump
Analyzer:
•

ATTACH

•

SPAWN

Also, the following new qualifiers are available for the EVALUATE,
EXAMINE, and SEARCH commands:
•

EVALUATE /PSL

•

EVALUATE /PTE

•

EVALUATE /SYMBOLS

•

EXAMINE /NOSUPPRESS

•

EXAMINE /PTE

•

SEARCH /LENGTH=length_specifier

•

SEARCH /STEPS=step_factor

The ATTACH command allows you to switch control of your terminal to
another process in your job. The /PARENT qualifier allows you to switch
control of your terminal to the parent process of the current process.
The SPAWN command creates a subprocess from the current process. The
context is copied from the current process to the spawned process.
The EVALUATE/PSL command evaluates the specified expression in the
format of a processor status longword.
The EVALUATE/PTE command interprets and displays the expression as a
page table entry (PTE). The individual fields of the PTE are separated and an
overall description of the PTE's type is provided.
The EVALUATE/SYMBOLS command specifies that all symbols that are
known to be equal to the evaluated expression are to be displayed.
The EXAMINE/NOSUPPRESS command inhibits the suppression of zeros
when displaying memory with one of the following qualifiers: /ALL, /PO,
/PI, /SYSTEM.
The SEARCH/LENGTH command specifies the size of the expression value
to be used for successful matching during searches of memory. The possible
values of this qualifier are: BYTE, WORD, and LONGWORD.
The SEARCH/STEPS command controls the granularity of searching through
the specified memory range. As each comparison of memory occurs, the value
of this qualifier determines the next memory location to be searched. The
possible step-factors are: BYTE, WORD, LONGWORD, and QUADWORD.
Note that the COPY command releases the dump pages in the paging file
so that they are available for system paging. Note that once the COPY
command has released the dump pages for paging use, the dump information
in these pages may be lost. Subsequent dump analysis should be carried out
on the copy of the dump file that was specified in the COPY command.

New and Changed Features

Logical operators have been added to the arithmetic operators in Section
6.2.2. They are the logical AND, logical OR, logical XOR, and logical NOT.
The SET PROCESS and SHOW PROCESS commands can now include
quoted strings in the process name in addition to the previous capital letters,
numbers, dollar sign ($), and underscore (_) characters.
The SHOW DEVICE command examples have been changed and now include
shadow devices.
The SHOW CRASH command register list now includes the system
identification register.
The SHOW PROCESS /RMS=IFAB display has been added to show the
changes to that display.
Other minor changes were made to correct typographical errors or slight
omissions.

System Dump Analyzer

System Dump Analyzer
The System Dump Analyzer is a utility that you can use to help
determine the cause of system failures. This utility is also useful for
examining the running system.

FORMAT

ANALYZE/Qt/a/zf/er file-spec[/SYMBOL=symbol-table]
Command Qualifiers

Defaults

/CRASH-DUMP
/RELEASE
/SYSTEM
/SYMBOL=

None.
None.
None.
SYS$SYSTEM:SYS.STB

Command Parameter

file-spec
The name of the file that contains the dump you want to analyze. At least
one field of the file specification is required, and it can be any field of the
file specification. The default file specification is the highest version of
SYSDUMP.DMP in your default directory.
If the /RELEASE qualifier is specified, SDA does not allow you to analyze
the specified dump file. The /RELEASE qualifier must be specified with
the /CRASH—DUMP qualifier and is useful only when the system paging
file is being used as a dump file. The /RELEASE qualifier has the effect of
releasing the blocks in the paging file that were used to store the dump. This
effectively and immediately deletes the dump file from the system paging file.

usage summary

invoking
To analyze a system dump, issue the ANALYZE/CRASH—DUMP command.
This causes SDA to read a dump file. If you do not specify the name of a
dump file, SDA prompts you for it.
To analyze the running system, issue the ANALYZE/SYSTEM command. Do
not specify a dump file when you use this qualifier.
To specify a symbol table to use in place of the default, use the /SYMBOL
qualifier.

Exiting
To exit from SDA, use the EXIT command. Note that the EXIT command also
causes SDA to exit from display mode. Thus, if SDA is in display mode, you
must use the EXIT command twice, once to exit from display mode, and a
second time to exit from SDA.

Directing Output
Use the SET OUTPUT command to send all output from SDA to a file.
You must supply the name of the file as a parameter to the SET OUTPUT
command. The file produced is 132 columns wide and is formatted for output
to a printer.
To redirect the output to your terminal, use the SET OUTPUT SYS$OUTPUT
command.

SDA-1

System Dump Analyzer

Use the SET LOG command to send a copy of all the commands you type
and all the output those commands produce to a file. You must supply the
name of the file as a parameter to the SET LOG command. The file produced
is 132 columns wide and is formatted for output to a printer.
Privileges/Restrictions
To examine the running system, your process must have Change-Mode-toKernel (CMKRNL) privilege. The CMKRNL privilege is needed to release the
page file dump blocks when using either the COPY command or specifying
the /RELEASE qualifier in the ANALYZE/CRASH_DUMP command.
To use SDA to analyze a dump, your process must have the privileges
necessary for reading the dump file. This usually requires system privilege
(SYSPRV), but your system manager can, if neccessary, allow less privileged
processes to read the dump files.

commands

Syntax
SDA> command [/qualifier[,...]] [parameter] [/qualifier[,...]]
System Dump Analyzer Commands
@ (Execute Procedure)
ATTACH
/PARENT
COPY
DEFINE
/ECHO
/IF_STATE
/KEY
/SET_ST ATE=state_name
/TERMINATE
EVALUATE
/CONDITION_VALUE
/PSL
/PTE
/SYMBOLS
EXAMINE
/ALL
/CONDITION_VALUE
/INSTRUCTION
/NOSKIP
/NOSUPPRESS
/PO
/P1
/PSL
/PTE
/SYSTEM
/TIME
EXIT
FORMAT
/TYPE=block_type
HELP
READ
/RELOCATE=expression
REPEAT
SEARCH
/LENGTH=length_specifier
/STEPS=step_factor
SET LOG

SDA-2

System Dump Analyzer

SET OUTPUT
SET PROCESS
/INDEX=index_value
/SYSTEM
SET RMS
SHOW CLUSTER
/CSID=n

/scs

SHOW CONNECTIONS
/ADDRESS=n
SHOW CRASH
SHOW DEVICE
/ADDRESS=n
SHOW HEADER
SHOW LOCK
/ALL
SHOW PAGE_TABLE
/GLOBAL
/SYSTEM
/ALL
SHOW PFN_DATA
/ALL
/BAD
/FREE
/MODIFIED
/SYSTEM
SHOW POOL
/ALL
/FREE
/HEADER
/IRP
/LRP
/NONPAGED
/PAGED
/SRP
/SUMMARY
/TYPE=block_type
SHOW PORTS
/ADDRESS=n
SHOW PROCESS
/ALL
/CHANNEL
/INDEX=nn
/LOCKS
/PO
/PI
/PAGE-TABLES
/PCB
/PHD
/PROCESS_SECTION_TABLE
/REGISTERS
/RMS=option
/SYSTEM
/WORKING_SET
SHOW RESOURCE
/ALL
/LOCKID=nn
SHOW RMS
SDA-3

System Dump Analyzer
Description

SHOW RSPID
/CONNECTION=n
SHOW STACK
/ALL
/EXECUTIVE
/INTERRUPT
/KERNEL
/SUPERVISOR
/USER
SHOW SUMMARY
/IMAGE
SHOW SYMBOL
/ALL
SPAWN
/INPUT=filespec
/NOLOGIC AL -NAMES
/NOSYMBOLS
/NOTIFY
/NOWAIT
/OUTPUT=filespec
/PROCESS=process_name
VALIDATE QUEUE
/SELF_RELATIVE

DESCRIPTION

The System Dump Analyzer is a utility that you can use to help determine the
cause of system failures. To use this utility effectively, you must be familiar
with VAX/VMS data structures.
This utility uses data in a crash dump file, a file that the system writes each
time the system fails. After a failure, this file contains a copy of the contents
of memory and a copy of the system's hardware context at the time of the
failure. See the VAX/VMS System Manager's Reference Manual and the next
section of this document for additional information regarding this file.
SDA performs the following operations:

SDA-4

•

Assigns a value to a symbol

•

Examines the memory of any process

•

Formats instructions and blocks of data

•

Displays data structures of devices

•

Displays the RMS data structures of a process

•

Displays memory management data structures

•

Displays a summary of all processes on the system

•
•
•
•

Displays the SDA symbol table

Reads global symbols from any object module

•

Searches memory for a given value

Copies the system dump file
Sends output to a file or device

System Dump Analyzer
Description

In addition to analyzing the system's dump file, SDA can perform the
operations listed previously on a running system without interrupting that
system's operation.

Introduction to SDA
When a fatal error within the system interferes with normal operations by
causing the system to fail, the VAX/VMS operating system writes information
concerning its status to a system dump file. The System Dump Analyzer
(SDA) reads, formats, and displays the contents of this file. You can use
SDA to display information on a video display terminal or to create hardcopy
listings.
Although SDA provides a great deal of information, it does not analyze all
the control blocks and data contained in memory. For this reason, in the
event of system failure it is extremely important that you send DIGITAL
a Software Performance Report (SPR) and a copy of the system dump file
written at the time of the failure.

System Management and SDA
The system manager must ensure that the system writes the dump file
whenever the system fails. The manager must also see that the dump file is
large enough to contain all the information to be saved, and that the dump
file is saved for analysis. The following sections describe these tasks.

2.1

The System Dump File
The VAX/VMS operating system can write information into the system dump
file only if the system parameter DUMPBUG is set. This parameter is set by
default. To alter DUMPBUG, as well as other system parameters, consult the

VAX/VMS System Manager's Reference Manual.
If the DUMPBUG parameter is set and the operating system fails, the system
writes the contents of the error-log buffers, processor registers, and physical
memory into the file SYS$SYSTEM:SYSDUMP.DMP, overwriting the contents
of that file. SDA reads this file and produces formatted displays of its
contents.
If the file SYSDUMP.DMP does not exist, the VAX/VMS operating system
writes the dump of physical memory into SYS$SYSTEM:PAGEFILE.SYS, the
system's paging file, overwriting the contents of that file. If the SAVEDUMP
system parameter is set, the dump file is is retained in PAGEFILE.SYS when
the system is booted. Otherwise, the entire paging file is used for paging and
the dump in the paging file is lost. To save the dump and free the pages in
the paging file taken up by the dump, this dump must be copied from the
paging file to another file. Sections 2.3 and 2.4, and the COPY command
description, indicate how to accomplish this.
Occasionally, you may want to free the pages in the paging file that are taken
up by the dump without having to copy the dump elsewhere. By issuing the
ANALYZE/CRASH_DUMP/RELEASE command, SDA immediately releases
the pages to be used for system paging, effectively deleting the dump. Note
that this command does not allow you to analyze the dump before deleting it.

SDA-5

System Dump Analyzer
Description

System dump files are set to NOBACKUP, in a manner similar to files used
for paging and swapping, which means that BACKUP will not copy them
to tape unless you use the qualifier /IGNORE=NOBACKUP with BACKUP.
When SDA copies the system's dump file to another file, it does not set the
file to NOBACKUP.

2.2

Setting the Size of the Dump File
The file SYSDUMP.DMP is furnished in the VAX/VMS software distribution
kit as an empty file located in SYS$SYSTEM, the system directory. The file
SYSDUMP.DMP is small. You must make it large enough to hold all the
information to be written when the system fails, or you must have the system
dumps written into the paging file.
To calculate the right size for your system's dump file,
SYS$SYSTEM:SYSDUMP.DMP, use the following equation:
Size-ol-d\imp-lile * size-of-physical-memory + 4

The size of the dump file is expressed in blocks, and the size of memory
is expressed in pages. The four extra pages are used to save the error-log
buffers and bugcheck information. Be sure to include any shared memory
when figuring the size of your system's physical memory.
Use the SYSGEN utility to set the size of the dump file. See the VAX/VMS
System Generation Utility Reference Manual for more information on
establishing the size of dump files.
If you want to use the paging file as the dump file, you must use SYSGEN to
set the system parameter SAVEDUMP and to set the size of the paging file.
Determine its minimum size according to the following equation:
Size-of-paging-file = size-of-physical-memory + 4 + 1000

Note that this is a minimum for saving a dump. The paging file must be
larger than this for most systems to avoid hanging the system. See the
VAX/VMS System Manager's Reference Manual for more information.

2.3

Saving System Dump Files
Every time the operating system writes information to SYSDUMP.DMP, it
writes over whatever was previously stored in the file. For this reason, the
system manager should save the contents of SYSDUMP.DMP after a system
failure has occurred.
The system manager can use the SDA COPY command or the DCL COPY
command. Either command can be used in your site-specific startup
procedure, but the SDA COPY command is preferred because it marks
the dump file as copied. This is particularly important if the dump was
written into the paging file, PAGEFILE.SYS. Section 2.4 discusses the startup
procedure in more detail. See the Commands Section for a description of the
COPY command.

SDA-6

System Dump Analyzer
Description

2.4

The System Startup Procedure
Because a listing of the SDA output is an important source of information
in determining the cause of a system failure, it is a good idea to make sure
that SDA produces such a listing after every failure. The system manager can
ensure the creation of a listing by modifying the SYSTARTUP.COM file in the
SYS$MANAGER directory so that it invokes SDA when the system is booted.
When called by the system startup procedure, SDA executes the commands
in the system's startup command procedure only if the system just failed.
SDA scans the dump file for a flag that indicates whether SDA has already
processed the file. This flag is cleared each time the operating system writes
a crash dump into SYSDUMP.DMP (unless an operator requested shutdown
with OPCCRASH.EXE). If the flag is cleared, SDA executes the startup
command procedure and sets the flag. If SDA finds that the flag is set,
however, it exits without executing the procedure.
The following example shows typical commands that might be added to your
site-specific startup command file to produce an SDA listing after each failure.
$ !
$ !
Print dump listing if system just failed
$ !
$ ANALYZE/CRASH_DUMP SYS$SYSTEM:SYSDUMP.DMP
COPY SYS$SYSTEM:SAVEDUMP.DMP
! Save dump file
SET OUTPUT LPAO:SYSDUMP.LIS
! Create listing file
SHOW CRASH
! Display crash
! information
SHOW STACK
! Show current stack
SHOW SUMMARY
! List all active
! processes
SHOW PROCESS/PCB/PHD/REG
! Display current process
SHOW SYMBOL/ALL
! Print system symbol

The COPY command in the preceding example saves the contents of the
file SYSDUMP.DMP. If your system's startup command file does not save a
copy of the contents of this file, this crash dump information will be lost in
the next system failure, when the system saves the information on the new
failure, overwriting the contents of SYSDUMP.DMP.
Note that if you use the paging file, SYS$SYSTEM:PAGEFILE.SYS, as the
crash dump file, you must use SDA to copy the dump from this file to
another file. If you fail to do this, the pages in the paging file that were used
to save information on the failure are not freed for use in paging, and your
system might hang during the execution of STARTUP.COM.
Thus, if you use the paging file as the crash dump file, you must include the
following commands in your system's STARTUP.COM file:
$ ANALYZE/CRASH.DUMP SYS$SYSTEM:PAGEFILE.SYS

Various SDA commands

SDA> COPY filespec
SDA> EXIT

SDA-7

System Dump Analyzer
Description

For another method of releasing the pages in the paging file without
analyzing the dump, see Section 2.1.

Using SDA
You can use SDA to examine the running system or the dump resulting from
a system failure. The next two sections describe these activities.
When you invoke SDA, by using DCL's ANALYZE/SYSTEM command or
by using DCL's ANALYZE/CRASH_DUMP command, SDA executes the
commands in the SDA initialization file, if such a file exists. SDA refers to its
initialization file by using the logical name SDA$INIT. This initialization file
can contain SDA commands that define keys, among other SDA commands.

3.1

Analyzing a System Dump
To enable SDA to read a dump file, your process must have:
•

Read access to the file that contains the dump

•

Read access to a copy of the system symbol table, SYS.STB, which SDA
reads by default

•

Enough virtual address space for SDA to map the entire dump file, to map
any symbol tables required, and to use for stacks

The files SYSDUMP.DMP and SYS.STB are included in the VAX/VMS
distribution kit. World access is denied to the SYSDUMP.DMP file. Because
the dump file can contain privileged information, it is a good idea for the
system manager to protect SYSDUMP.DMP from universal read access.
See the VAX/VMS System Manager's Reference Manual for details on how to
change a file's protection.
To ensure that SDA has the correct amount of virtual address space, the value
of the system parameter VIRTU ALP AGECNT must be larger than the size of
the system's dump file by approximately 2000 pages.
The suggested parameter setting is a sufficient guideline for the majority of
VAX/VMS installations. Further increases in the parameter may be required
if your particular installation places extra heavy demands upon the virtual
address space of the process.
For more information on process privileges, see the VAX/VMS System
Manager's Reference Manual. For a description of system parameters, see
the VAX/VMS System Generation Utility Reference Manual. For a description of
the Authorize Utility, see the VAX/VMS Authorize Utility Reference Manual.
If the conditions listed previously are satisfied, you can invoke SDA to
examine a dump file with the DCL command ANALYZE/CRASH—DUMP. If
you do not specify a dump file with this command, SDA prompts you for the
name of the file, as follows:
$ ANALYZE/CRASH.DUMP
_Dump File:

The default file specification is SYS$DISK:[default-dir]SYSDUMP.DMP, where
SYS$DISK and [default-dir] represent, respectively, the disk and directory
specified in your last SET DEFAULT command. (See Section 6 for more
information about SDA command formats.)

SDA-8

System Dump Analyzer
Description

Reading the System Dump File
When you invoke SDA to analyze the system dump file, SDA gathers, from
the specified dump file, the information it needs to create its displays. Under
certain conditions, some memory locations might not be saved in the system
dump file.
For instance, if SYSDUMP.DMP is too small, the operating system cannot
copy all of memory to the file when a system failure occurs. For most
systems, this means that the system's page table (SPT) is not included in the
dump. SDA cannot analyze a dump unless the SPT is included in the dump
in its entirety.
The SPT, which contains one entry for each page of system virtual address
space, is the first data structure SDA looks for when it reads the system dump
file. As long as SYSDUMP.DMP contains the SPT, SDA can map the contents
of that file.
Only the contents of physical memory are saved when the system fails.
Thus, if you use an SDA command to access a virtual address that has no
corresponding physical address, SDA generates an error message:
%SDA-E-NOTINPHYS, xxxxxxxx : not in physical memory

In the preceding message, xxxxxxxx represents the virtual address that is not
in physical memory.
Also, during halt/restart bugchecks, the contents of general registers are not
preserved. If such a bugcheck occurs, SDA indicates in the SHOW CRASH
display that the contents of the registers were destroyed.

Analyzing a Running System
Occasionally, VAX/VMS encounters an internal problem that hinders system
performance without causing a system failure. By allowing you to examine
the running system, SDA provides the means to search for the solution to the
problem without disturbing the operating system.
To examine the running system, your process needs change-mode-to-kemel
(CMKRNL) privilege. (See the VAX/VMS System Manager's Reference Manual
for a discussion of this and other privileges.) If your process has CMKRNL
privilege, you can invoke SDA to examine the system with the following DCL
command:
$ ANALYZE/SYSTEM

SDA automatically sets process context to that of your process. (For an
explanation of process context, see the description of the SET PROCESS
command in the Commands section of this manual.)
In analyzing the system dump file, SDA maps the entire file; but in analyzing
the running system, SDA does not map the entire system. Instead, each time
you give a command, SDA retrieves only the information it needs to process
that command. If you reissue the command, SDA fetches the information
again. In this way, SDA updates requested information to reflect the current
state of the running system.

SDA-9

System Dump Analyzer
Description

You can use the ANALYZE/SYSTEM command to examine the stack
and memory of a process that is stalled in a scheduler state, such as a
miscellaneous wait (MWAIT) or a suspended (SUSP) state. The VAX/VMS
System Manager's Reference Manual provides more information about
scheduler states.

5.1

Building the SDA Symbol Table
After locating and reading the system dump file, SDA attempts to read the
system's symbol table file. This file, named SYS.STB, contains the global
symbols used by the VAX/VMS operating system.
SDA looks for SYS.STB in the system directory SYS$SYSTEM. Once SDA
finds SYS.STB, it copies the file's contents to the SDA symbol table. If SDA
cannot find the system symbol table file, it halts with a fatal error.
In addition to having SDA read symbols in SYS.STB, you might find it useful
for SDA to read the symbols in SYSDEF.STB, which contains symbols that
define many of the system's data structures, including those in the I/O
database. You can cause SDA to read these symbols by using the READ
command described in the Commands section of this manual.
When SDA finishes building its symbol table, it displays a message
identifying itself and the immediate cause of the crash. In the following
example, the cause of the crash was a nonzero mutex count at the end of the
execution of a system service.
VAX/VMS System dump analyzer
Dump taken on 16-Feb-1986

10:16:49.20

MTXCNTNONZ, Mutex count nonzero at system service exit
SDA>

The SDA> prompt indicates that you can use SDA interactively and enter
SDA commands, or send selected information to a file, or print selected
information on a printer. Refer to the description of the SET OUTPUT
command in the Commands section of this manual for directions on defining
output files, and to the description of the SET LOG command for directions
on defining log files.

SDA Command Format
The following sections describe the format of SDA commands and the
expressions you can use with SDA commands.

6.1

General Command Format
SDA uses a command format similar to that used by the DIGITAL Command
Language (DCL) interpreter. You issue commands in this general format:
commaud-naune[/qualifier. . .]

[parauneter] [/qualifier. . .]

[!comment]

The command-name is an SDA command. Each command tells the utility to
perform a function. Commands can consist of one or more words, and can be
abbreviated to the number of characters that make the command unique. For
example, SH stands for SHOW, and SE stands for SET.

SDA-10

System Dump Analyzer
Description

The parameter is the target of the command. For example, SHOW PROCESS
RUSKIN tells SDA to display the context of the process RUSKIN. The
command EXAMINE 80104CD0;40 displays the contents of 40 bytes of
memory, beginning with location 80104CD0.
When the parameter is a file specification, the default device is SYS$DISK, the
device specified in your most recent SET DEFAULT command. Likewise, the
default directory is the directory specified in the most recent SET DEFAULT
command. See the VAX/VMS DCL Dictionary for a description of the DCL
command SET DEFAULT.
The /qualifier modifies the action of an SDA command. A qualifier is always
preceded by a slash (/). Several qualifiers can follow a single parameter or
command name, but each must be preceded by a slash. Qualifiers can be
abbreviated to the shortest string of characters that uniquely identifies the
qualifier.
The Icomment is text that comments upon the command. Such comments are
useful for documenting SDA command procedures. However, the exclamation
point (!) may be used within an expression in a command to indicate a logical
OR operation. If the exclamation point (!) is used outside of the expression,
SDA ignores the exclamation point and all characters that follow it on the
same line (they are treated as a comment).

6.2

Expressions
You can use expressions as parameters for some SDA commands. For
example, the SEARCH and EXAMINE commands use expressions. To create
expressions, you can use any of the following:
•

Radix operators

•

Arithmetic and logical operators

•

Precedence operators

•

Symbols

•

Numerals

Numerals are the digits you can type on your keyboard. The following
sections describe the use of the other components of expressions.

6.2.1

Radix Operators
Radix operators determine which radix SDA uses to evaluate expressions.
You can use one of the three radix operators to specify the radix of the
numeric expression that follows the operator:
•

''X (hexadecimal)

•

"O (octal)

•

"D (decimal)

The default radix is hexadecimal. SDA displays hexadecimal numbers with
leading zeros and decimal numbers with leading spaces.

SDA~11

System Dump Analyzer
Description

6.2.2

Arithmetic and Logical Operators
Arithmetic and logical operators are useful in forming expressions. There are
two types: unary and binary operators. Unary operators affect the value of
the expression that follows them. Binary operators combine the operands
that precede and follow them. The SDA arithmetic operators perform integer
arithmetic on 32-bit operands.
SDA recognizes the following six unary operators:
Operator

Action

Performs a logical NOT of the expression

Makes the value of the expression positive

Makes the value of the expression negative

Evaluates the following expression as a virtual address, then uses
the contents of that address as value

Adds 80000000 to the value of the expression

Adds 7FFE0000 to the value of the expression

The unary operator G corresponds to the first virtual address in system space;
the unary operator H corresponds to a convenient base address in the control
region of a process. The binary operators are the following:
Operator

Action

Addition

Subtraction

Multiplication

Logical AND

Logical OR

Logical XOR

Division

Arithmetic shifting

SDA performs logical AND, OR, and XOR operations, and multiplication,
division, and arithmetic shifting before addition and subtraction. In division,
SDA truncates the quotient to an integer, if necessary, and does not retain
a remainder. Note that the logical OR operator (!) is valid within the
expression in a command that uses an arithmetic expression. Otherwise,
in an SDA command, the DCL command line interpreter may interpret the
exclamation point as the start of a comment on the command line.

6.2.3

Precedence Operators
SDA uses parentheses as precedence operators. Expressions enclosed
in parentheses are evaluated first. SDA evaluates nested parenthetical
expressions from the innermost to the outermost pairs of parentheses.

SDA-12

System Dump Analyzer
Description

6.2.4

Symbols
Names of symbols can contain from 1 to 31 alphanumeric characters and can
include the dollar sign ($) and underscore (_) characters. Symbols can take
values from -7FFFFFFF to 7FFFFFFF (hexadecimal).
SDA copies symbols into its symbol table from the SYS.STB file. Additional
symbols can be taken from other symbol tables and added to the SDA symbol
table with the READ command. Symbols can also be created by the DEFINE
command.
In addition, SDA provides the following symbols:
Symbol

Meaning

. (the period character)

The current location

The argument pointer

CLUSTRLOA

The base address of loadable VAXcluster
code

nnDRIVER

The base address of the driver prologue table
(DPT); a symbol exists for each loaded device
driver in the system

ESP

The executive-mode stack pointer

The frame pointer

FPEMUL

The base address of the code that emulates
floating-point instructions

80000000, the base address of system
space

7FFE0000

KSP

The kernel-mode stack pointer

MCHK

An address within loadable CPU-specific
routines

The base address of loadable multiprocessor
code

MSCP

The address of loadable MSCP-server code

POBR

The base register for the program region

POLR

The length register for the program region

P1BR

The base register for the control region

P1LR

The length register for the control region

The program counter

PSL

The processor-status longword

RO through R11

The general registers

RMS

The base address of the RMS image

SCSLOA

The base address of loadable common SCS
services

SDA-13

System Dump Analyzer
Description

Symbol

Meaning

The current stack pointer of a process

SSP

The supervisor-mode stack pointer

SYSLOA

The base address of loadable processorspecific system code

USP

The user-mode stack pointer

The register symbols correspond to the registers saved as part of the hardware
context of the current process. (See the SET PROCESS command in the
Commands section of this manual for a definition of the current process.) For
example, the command EXAMINE @USP displays the contents of the user¬
mode stack pointer, the register that contains the address of the user-mode
stack.
The notation nn within the symbol nnDRIVER represents the 2-letter, generic
device name (for example, LPDRIVER).
When SDA displays an address, it displays that address both in hexadecimal
and as a symbol, if possible. If the address is within FFF of the value of
a symbol, SDA displays the symbol plus the offset from the value of that
symbol to the address. If more than one symbol's value is within FFF of the
address, SDA displays the symbol whose value is the closest. If no symbols
have values within FFF of the address, SDA displays no symbol. For an
example, see the description of the SHOW STACK command.

Analyzing System Failures
The next sections discuss how the VAX/VMS operating system handles
internal errors, and suggests procedures that can aid you in determining the
cause of these errors. The last sections illustrate, through detailed analysis
of a sample system failure, how SDA helps you find the cause of operating
system problems.
For a complete description of the commands discussed in the sections that
follow, refer to the last part of the SDA documentation, which describes all
the SDA commands in alphabetical order.

7.1

General Procedure for Analyzing System Failures
When the VAX/VMS operating system detects an internal error so severe
that normal operation cannot continue, it signals a condition known as a fatal
bugcheck and shuts itself down. A bugcheck code describes the error; each
error is associated with a code.
To resolve the problem, you must find the reason for the bugcheck. Most
failures are caused by errors in user-written device drivers or other privileged
code not supplied by DIGITAL. To identify and correct these errors, you need
a listing of the code in question.
Occasionally a system failure is the result of a hardware failure or an error
in code supplied by DIGITAL. A hardware failure requires the attention of
Digital Field Service. To diagnose an error in code supplied by DIGITAL,
you need listings of that code, which are supplied on microfiche with your
VAX/VMS software kit.

SDA-14

System Dump Analyzer
Description

Start the search for the error by locating the line of code that signaled the
bugcheck. Invoke SDA and use the SHOW CRASH command to display the
content of the program counter (PC). The content of the PC is the address of
the next instruction after the instruction that signaled the bugcheck.
The PC often contains an address in the exception handler, which signaled
the bugcheck but did not cause it. In this case, the address of the instruction
that caused the bugcheck is located on the stack. Use the SHOW STACK
command to display the contents of the stack. See Section 7.2 for information
on how to proceed for several types of bugchecks.
Once you have found the address of the instruction that caused the bugcheck,
you need to find the module in which the failing instruction resides. Use the
SHOW DEVICE command to determine if the instruction is part of a device
driver.
If it is not part of a driver, examine the linker's map of the module or modules
you are debugging to determine if the instruction that caused the bugcheck is
in your programs.
If it is not part of a driver and not part of your programs, examine the system
map in the file SYS$SYSTEM:SYS.MAP. This file lists the addresses of each
VAX/VMS module that is part of SYS.EXE, the system image. Compare the
address in the PC with the addresses in the system map file to locate the
module that contains the instruction to which the PC points.
If you do not have the system map file, you can use the SDA symbol table.
All the global symbols that appear in SYS.MAP also exist in the file SYS.STB,
which SDA reads when you invoke it. To determine the offset from the
closest global symbol, you can issue the command
SDA> EXAMINE (BPC

Note, however, that the closest symbol might not be in the same module as
the code you are examining.
Once you have narrowed the search to a particular module, subtract the
module's starting address from the address in the PC to get the offset into the
module of the failing instruction.
Now, to determine the general cause of the system failure, examine the code
that signaled the bugcheck.

7.2

Fatal Bugcheck Conditions
Bugchecks frequently are caused by one of two conditions: a fatal exception
or an illegal page fault.

7.2.1

Fatal Exceptions
An exception is fatal when it occurs while the following conditions exist:
•

The process is using the interrupt stack

•

The process is executing above IPL 2 (IPL$_ASTDEL)

•

The process is executing in a privileged (kernel or executive) processor
access mode and has not declared a condition handler to deal with the
exception

SDA-1 5

System Dump Analyzer

Description
When the system fails, it lists the approximate cause of the failure on the
console terminal as shown following. SDA displays the same information
when you use the SHOW CRASH command. SDA displays one of the
following reasons for a fatal exception:
FATALEXCPT, Fatal executive or kernel mode exception
INVEXCEPTN, Exception while above ASTDEL or on interrupt stack
SSRVEXCEPT, Unexpected system service exception

For INVEXCEPTN and SSRVEXCEPT bugchecks, two lists of arguments
are pushed on the stack, the signal array and the mechanism array. These
lists contain important information about the exception that resulted in the
bugcheck.
Although there are several possible exception conditions, access violations are
most common. The rest of this section discusses access violations in detail.
For more information on other kinds of exceptions and condition handling,
see the VAX/VMS Run-Time Library Routines Reference Manual.
When the hardware detects an access violation, information useful in finding
the cause of the violation is pushed onto the kernel-mode stack. If the
access violation occurred when the system was using the interrupt stack, the
argument lists go on the interrupt stack. This information is described by
three arrays.
An argument list is a series of longwords, in which the first longword contains
the number of longwords that follow. For an exception, the first argument
list that appears on the stack contains the addresses of the next two arrays.
In this way, the first argument list, or array, that may appear on the stack
contains three longwords: the first contains the number of longwords that
follow, the second is the address of a signal array, and the third is the address
of a mechanism array. Thus, each longword following the first contains the
address of the next two lists called the mechanism array and the signal array.
The general form of an argument list or array is shown in Figure SDA-1. The
first argument list on the stack is shown in Figure SDA-2.
The first longword in the mechanism array or the signal array contains the
number of longwords that follow in each. The longwords in the mechanism
array contain information that describes conditions at the time of the
exception. These conditions are the stack frame, the stack depth, RO, and
Rl. The longwords in the signal array contain information that describes the
exception code, exception parameters (if any), the program counter (PC), and
the PSL. A mechanism array is shown in Figure SDA-3, and a signal array is
shown in Figure SDA-4
The first array does not always appear on the stack. If it does not, the
mechanism array is the first. The mechanism array describes the process that
was executing when the exception occurred. Figure SDA-3 illustrates the
sequence of longwords in a mechanism array.

SDA-16

System Dump Analyzer
Description

Figure SDA—1

An Argument List on the Stack

array header:
longword 1:
longword 2:

longword n-1;
longword n:

ZK-1919-84

Figure SDA~2

The First Argument List on the Stack

The values contained in the mechanism array are defined as follows:

SDA-17

System Dump Analyzer
Description

Value

Meaning

00000004

The number of longwords that follow. In a mechanism array, this
value is always 4.

Frame

The address of the stack frame.

Depth

The stack depth.

The contents of RO at the time of the exception.

The contents of R1 at the time of the exception.

The next argument list on the stack is the signal array. For access violations,
the signal array is set up as follows:
Figure SDA-4

A Signal Array

The values in the signal array are defined as follows:
Value

Meaning

00000005

The number of longwords that follow. For access
violations, this value is always 5.

oooooooc

The exception code. This value, C (hexadecimal),
represents an access violation.

Reason mask

A longword, of which the lowest three bits, if set,
indicate that the instruction caused a length violation (bit
0), referenced the process page table (bit 1), or attempted
a read or modify operation (bit 2; read=0, write=1).

Virtual address

The virtual address that the system tried to reference.

The program counter. The PC contains the address of the
instruction that signaled the exception.

PSL

The processor status longword at the time of the
exception.

Signal arrays differ in length, depending on the kind of exception the system
detects. They contain a minimum of three arguments: the exception code, the
PC, and the PSL at the time of the exception. You can identify the exception
code by using the EVALUATE/CONDITION command.

SDA-18

System Dump Analyzer
Description

If VAX/VMS encounters a fatal exception, you can find the code that signaled
it by examining the PC in the signal array. Use the SHOW STACK command
to display the stack in use when the failure occurred, then locate the
mechanism and signal arrays. Once you obtain the PC, which points to
the instruction that signaled the exception, you can identify the module by
the procedure outlined in Section 8.3.
7.2.2

Illegal Page Faults
VAX/VMS also signals a bugcheck when a page fault occurs while the
interrupt priority level (IPL) is greater than 2 (IPL$_ASTDEL). When
VAX/VMS fails because of an illegal page fault, it prints the following
message on the console terminal:
PGFIPLHI, Page fault with IPL too high

When an illegal page fault occurs, longwords containing the following
information are pushed onto the operating stack.
Figure SDA-5

The Stack Following an Illegal Page-Fault Error

The longwords pushed onto the stack are listed following.
Longword

Contents

The contents of R4 at the time of the bugcheck.

The contents of R5 at the time of the bugcheck.

Reason mask

Virtual address

The virtual address being referenced by the Instruction
that caused the page fault.

The program counter. The PC contains the address of the
instruction that was being executed when the page fault
occurred.

PSL

The contents of the processor status longword at the
time of the bugcheck.

SDA-19

System Dump Analyzer
Description

If the operating system detects a page fault while the IPL is higher than
2, you can obtain the address of the instruction that caused the fault by
examining the PC pushed onto the current operating stack. Follow the steps
outlined in Section 8.3 to determine which module issued the instruction.

A Sample System Failure
This section steps through the analysis of a system failure caused by an
example device driver. Three events lead up to this failure:

8.1

The line printer goes off line for three hours.

The line printer comes back on line.

The VAX/VMS operating system signals a bugcheck, writes information to
the system dump file, and shuts itself down.

Identifying the Bugcheck
Invoke SDA to analyze the system dump file. The initialization message
indicates the type of bugcheck that occurred as follows:
VAX/VMS System dump analyzer
Dump taken on 31-JAN-1985

16:34:31.23

INVEXCEPTN, Exception while above ASTDEL or on interrupt stack
SDA>

VAX/VMS encountered an exception that caused it to signal a bugcheck.
Signal and mechanism arrays are created on the current operating stack.

8.2

Identifying the Exception
Use the SHOW STACK command to display the current operating stack,
which in this case is the interrupt stack. The following example shows the
interrupt stack and the signal and mechanism arrays. See the description of
the SHOW STACK command for a complete description of the format of the
stack display.

SDA-20

System Dump Analyzer
Description

Current operating stack (INTERRUPT)
8006A378

8000844B

'> 8006A398
8006A39C
8006A3A0
8006A3A4
8006A3A8
8006A3AC
8006A3B0
8006A3B4
8006A3B8
8006A3BC
80O6A3C0
8006A3C4
8006A3C8
8006A3CC
8006A3D0
8CX)6A3D4
8006A3D8

7FFDC340
8006A3A0
80004E7D
04080009
00000004
7FFDC368
FFFFFFFD
8001774E
0000074F
00000001
00000005
OOOOOOOC
00000000
80069E00
8006D003
04080000
80009604

ACP$WRITEBLK+0A0

EXE$REFLECT+0D4

EXE$F0RKDSPTH+01C

The mechanism array begins at address 8006A3A8 and ends at address
8006A3B8. Its first longword contains 00000004. The signal array begins
at address 8006A3C0 and ends at 8006A3D4. Its first longword contains
00000005 and its second longword contains OOOOOOOC. Examination of the
signal array shows that:
•

The exception code is C (hexadecimal), which means that an access
violation occurred.

•

The reason mask is zero, which means that the instruction generated a
protection violation (instead of a length violation) when it tried to read the
location (rather than write to it).

•

The virtual address is 80069E00, the address that the instruction tried to
reference.

•

The PC contains 8005D003, the address of the instruction that signaled
the exception.

•

The IPL was 8 at the time of the exception (shown by bits 16 through 20
of the PSL).

•

The current operating stack was the interrupt stack (bit 26 of the PSL is
set to 1).

•

The process was executing in kernel mode at the time of the exception
(shown by bits 24 and 25 of the PSL).

Use the SHOW PAGE—TABLE command to display the system page table, as
shown in the example following. The page containing location 80069E00 is
not available to any access mode (a null page); thus the virtual address is not
valid.

SDA-21

80068400
80068600
80068800
80068A00
80068C00
80068E00
80069000
80069200
80069400
80069600
80069800
80069A00
80069C00

80777B08
80777B0C
80777B10
80777B14
80777B18
80777B1C
80777B20
80777B24
80777B28
80777B2C
80777B30
80777B34
80777B38

7C40FFC8
7C40FFC8
7C40FFC8
7C40FFC8
7C40FFC8
7C40FFC8
7C40FFC8
7C40FFC8
7C40FFC8
7C40FFC8
7C40FFC8
780016C9
78000E15

STX
STX
STX
STX
STX
STX
STX
STX
STX
STX
STX
TRANS
TRANS

UR
UR
UR
UR
UR
UR
UR
UR
UR
UR
UR
UR
UR

K
K
K
K
K
K
K
K
K
K
K
K SYSTEM
K SYSTEM

FREELST 00
FREELST 00

01
01

0
0

0040FFC8
0040FFC8

80777B3
80777B3

40 NULL PAGES

8.3

Locating the Source of the Exception

Because the printer went off line and then on line, as shown on
listing, the problem might exist in the driver code. SDA can he
determine which driver might contain the faulty code.

8.3.1

Finding the Driver by Using the Program Counter

When SDA builds its internal symbol table, it defines a symbol,
nnDRIVER, for each device driver connected to the system. Th
represents the base of the driver prologue table (DPT).

The DPT describes the driver. All of the driver prologue tables
list. Each DPT is part of the device driver it describes and is fol
driver's code. The following example shows a partial list of the
display generated by the SHOW DEVICE command.
SDA> SHOW DEVICE
I/O data structures
DDB list

Address

Controller

ACP

Driver

FllXQP

DPT

DPT size

80000ECC

HELIUMSDBA

DBDRIVER

800F7AD0

08FD

80001040

OPA

OPERATOR

80001622

0061

8000126C
80001460

MBA
NLA

MBDRIVER
NLDRIVER

800016B0
800016E9

0578
06A3

801E2800

HELIUM$DMA

FllXQP

DMDRIVER

800B5CB0

OAAO

801E2980

HELIUM$DLA

FllXQP

DLDRIVER

800B6A50

08D0

Find the PC in the signal array, and examine that location in M
instruction format by using the EXAMINE/INSTRUCTION com
address lies within the first 1000 (hexadecimal) bytes of a device
identifies that driver by showing the address as a symbol, nnDR
offset from that symbol to the address in question. The address
the symbol nnDRIVER is the base address of the driver's DPT.

SDA-22

System Dump Analyzer
Description

If SDA is unable to find a symbol within 1000 (hexadecimal) bytes of the
memory location you specify, it displays the location as an absolute address.
This result often, but not always, means the instruction that caused the
exception is not part of a device driver.
To determine whether an instruction is or is not part of a driver, use the
SHOW DEVICE command (see the Commands section in this manual) to
display the starting addresses and lengths of the drivers in the system. If the
address of the failing instruction falls within the range of addresses shown for
a given driver, the failing instruction is a part of that driver.
In the example following, the instruction that caused the exception is located
within the printer driver.
SDA> EXAMINE/INSTRUCTION 8005D003
LPDRIVER+2B3
MOVE
(R3)+,(R0)

8.3.2

Calculating the Offset into the Driver's Program Section
The offsets that SDA displays are offsets from the DPT. These offsets do not
match the offsets shown in driver listings. The offsets in a MACRO-assembler
listing are offsets from the beginning of the program section (PSECT) in
which that instruction appears. Because a driver usually contains more than
one PSECT, you must use the driver's map to determine the following:
•

The PSECT that contains the instruction

•

The base address of that PSECT, relative to the base address of the DPT

To calculate the failing instruction's offset into the driver's program-section
listing, subtract the PSECT base from the offset given by SDA.

8.4

Finding the Problem Within the Routine
To find the problem within the routine, examine the printer's driver code. In
this sample system failure, the instruction that caused the exception is MOVB
(R3)+,(R0). To check the contents of R3, use the EXAMINE command as
follows:
SDA> EXAMINE R3
R3: 80069E00 "_"

The invalid virtual address is stored in R3.
570 STARTIO:
571
MOVL
UCB$L_IRP(R5).R3
:Retrieve address of I/O packet
572
MOVW
IRP$L_MEDIA+2(R3). 573
UCB$W_B0FF(R5)
;Set number of characters to print
574
MOVL
UCB$L_SVAPTE(R5),R3
;Get address of system buffer
;Get address of data area
575
MOVAB
12(R3).R3
MOVL
UCB$L_CRB(R5),R4
;Get address of CRB
576
MOVL
(DCRB$L_INTD+VEC$L..IDB(R4),R4 ;Get device CSR address
577
578
579
580
582
583
584
585
586
587
588
589
590
591

; START NEXT OUTPUT SEQUENCE
10$: ADDL3
MOVZWL
MOVW
BRB
20$: BITW
BLEQ
MOVB
FREEIB
25$: SOBGEQ
BRW

#LP_DBR,R4.R0
UCB$W_B0FF(R5),R1
#“X8080,R2
25$
R2.(R4)
30$
(R3)+.(RO)
R1.20$
70$

:Find address of data buffer register
:Get number of characters remaining
;Get control register test mask
;Start output
:Printer ready or have paper problem?
;If LEQ not ready or paper problem.
;output next character
;Flush instruction buffer and delay
;Any more characters to output?
;A11 done. BRW to set return status

SDA-23

System Dump Analyzer
Description

The instruction that caused the system failure is at line 588. The contents of
R3 have probably been incremented too many times.

8.4.1

Examining the Routine
The MOVB instruction is part of a routine that reads characters from a buffer
and writes them to the printer. The routine contains the loop of instructions
that starts at the label 20$ and ends at 25$. This loop executes once for each
character in the buffer, performing these five steps:

The driver checks the printer's status register to see if the printer is ready.

2 If the printer is ready, the driver gets a character from the buffer and
moves it to the printer's data register, to which RO points; then it
decrements Rl, which contains the count of characters left to print. If
R1 contains a number greater than zero, control is passed back to the
instruction at 20$, and the loop begins again.

3 Steps 1 and 2 are repeated until the contents of Rl is 0 or the printer
signals that it is not ready.

4 If the printer signals that it is not ready, the driver transfers control to 30$
(line 587), the beginning of a routine that waits for an interrupt from the
printer.

5 When the printer is ready, it interrupts the driver, and execution of the
loop resumes.
Examine the code to determine which variables control the loop. The byte
count (BCNT) is the number of characters in the buffer. This value controls
the number of times the loop is executed. Note that BCNT is set by a
function decision table (FDT) routine and that this routine sets the value of
BCNT to the number of characters in the buffer. Note also that the number of
characters left to be printed is represented by the byte offset (BOFF), the offset
into the buffer at which the driver finds the next character to be printed.
Because the exception is an access violation, either R3 or RO contains an
incorrect value. Because the instruction at 10$ places the address of the databuffer register into RO, and no other instruction references RO until the MOVB
instruction does, it is probable that RO contains the correct value.
You can check whether R3 contains an incorrect value, however, by noting
that the instruction at line 576 (MOVE UCB$L_CRB(R5),R4) moves the
address of the printer's CRB into R4 and that no instruction changes the
contents of R4 between lines 576 and 588. Although it is possible that the
UCB contains the wrong address, it is unlikely. Thus, the contents of R3 seem
to be the cause of the failure.
The most likely reason that the contents of R3 are wrong is that the MOVB
instruction at line 588 executes too many times. You can check this by
comparing the contents of UCB$W_BOFF and UCB$W_BCNT. If UCB$W_
BOFF contains a larger value than that in UCB$W_BCNT, then R3 contains a
value that is too large, indicating that the MOVB instruction has incremented
the contents of R3 too many times.

SDA-24

System Dump Analyzer
Description

8.4.2

Checking the Values of Key Variables
Because this start-I/O routine requires that R5 contain the address of the
printer's UCB, and because several other instructions reference R5 without
error before any instruction in the loop does, you can assume that R5 contains
the address of the right UCB. To compare BOFF and BCNT, use the command
FORMAT @R5 to display the contents of the UCB, as shown following.
SDA> read SYS$SYSTEM:SYSDEF.STB
SDA> FORMAT (DR5
8005D160

8005D168
8005D16A
8005D16B

UCB$L_RQFL
UCB$L_FQFL
UCB$L.RQBL
UCB$L_FQBL
UCB$W_SIZE
UCB$B_TYPE
UCB$B_FIPL

8005D1C8
8005D1CC
8006D1CE
8005D1D0
8005D1D1
8006D1D2

UCB$L_SVAPTE
UCB$W_B0FF
UCB$W_BCNT
UCB$B_ERTCNT
UCB$B_ERTMAX
UCB$W_ERRCNT

80062720
0795
006D
00
00
0000

8005D164

800039A8
800039A8
0080
10

SDA>

If you have only one printer in your system configuration, you need not use
the FORMAT command. Instead, you can use the command SHOW DEVICE
LP. Because only one printer is connected to the VAX processor, only one
UCB is associated with a printer for SDA to display.
The output produced by the FORMAT @R5 command shows that UCB$W_
BOFF contains a value greater than that in UCB$W_BCNT; it should be
smaller. Therefore, the value stored in BOFF is incorrect.
Thus, the value of BOFF is not the number of characters that remain in the
buffer. This value is used in calculating an address that is referenced at an
elevated IPL. When this address is within a null page (unreadable in all access
modes), an attempt to reference it causes the system to fail.

8.4.3

Identifying and Fixing the Defective Code
Examine the printer driver code to locate all instructions that modify UCB$W_
BOFF. The value changes in two circumstances:
•

Immediately after the driver detects that the printer is not ready and that
the problem is not a paper problem (line 598).

•

When the wait-for-interrupt (WFIKPCH) routine's timeout count of 12
seconds is exhausted (lines 603 and 615). At this time, the contents of Rl,
plus one is stored in UCB$W_BOFF (line 616).

When the printer times out, the driver should not modify UCB$W_BOFF.
It does so, however, in line 616. The driver should modify the contents of
UCB$W_BOFF only when it is certain that the printer printed the character.
When the printer times out, this is not the case. Furthermore, the WFIKPCH
routine preserves only registers R3, R4, and R5, so only these registers can be
used unmodified after the execution of the WFIKPCH routine. Thus the use
of Rl in line 616 is an error.

SDA-25

System Dump Analyzer
Description

To correct the problem, change the WFIKPCH argument (line 60) so that,
when the printer times out, the WFIKPCH macro transfers control to 50$
rather than to 40$.
596
597 30$: BNEQ
40$
#1,R1.UCB$W_B0FF(R5)
ADDW3
598
DSBINT UCB$B.DIPL(R5)
599
BITW
#*X80.LP_CSR(R4)
600
601
BNEQ
35$
BISB
#“X40.LP_CSR(R4)
601
WFIKPCH 40$.#12
603
604
lOFORK
BRB
605
10$
606
607 35$:
ENBINT
608
CLRW
609
BRB
610

LP_CSR(R4)
10$

;If NEQ paper problem
;Save number of characters remaining
;Disable interrupts
;Is it ready now?
;If NEQ, yes, it's ready
;Set interrupt enable
;Wait for ready interrupt
;Create a fork process
;
... and start next output

:Enable system interrupts
;Disable device interrupts
;Go transfer more characters

611 ;
612 ; PRINTER HAS PAPER PROBLEM
613 ;
614
UCB$L_LP_OFLCNT(R5)
;Clear offline counter
615 40$: CLRL
616
ADDW3
#1.R1.UCB$W_B0FF(R5) :Save number of characters remaining
LP_CSR(R4)
;Disable printer interrupt
617 50$: CLRW
;Lower to fork level
SETIPL UCB$B_FIPL(R5)
618
TSTW
LP_CSR(R4)
;Printer still have paper problem?
619
;If LSS yes
620
BLSS
55$
#15.UCB$L_LP_TIME0UT(R5)
;Set timeout value
621
MOVL
; ... and start next output
622
BRB
10$

8.5

Inducing a System Failure
If the operating system is not performing well and you want to create a
dump you can examine, you must induce a system failure. Occasionally a
device driver or other user-written, kernel-mode code can cause the system
to execute a loop of code at a high priority, interfering with normal system
operation. This can occur even though you have set a breakpoint in the
code if the loop is encountered before the breakpoint. To gain control of the
system in such circumstances, you must cause the system to fail and then
reboot it.
If the system has suspended all noticeable activity (if it is "hung"), see the
examples of causing system failures at the end of this section.

Meeting Crash Dump Requirements
The following requirements must be met before the VAX/VMS system can
write a complete crash dump:

You must not halt the system until the console dump messages have been
printed in their entirety and the memory contents have been written to
the crash dump file. Be sure to allow sufficient time for these events to
take place or make sure that all disk activity has stopped before using the
console to halt the system.

2 There must be a crash dump file in SYS$SYSTEM: named either
SYSDUMP.DMP or PAGEFILE.SYS.
If the dump file is SYSDUMP.DMP, it must be at least four blocks larger
than physical memory.

SDA-26

System Dump Analyzer
Description

If SYSDUMP.DMP is not present, VAX/VMS will write crash dumps to
PAGEFILE.SYS. In this case, PAGEFILE.SYS must be at least 1004 blocks
larger than physical memory, and the SYSBOOT parameter SAVEDUMP
must be 1 (the default is 0).
3

The SYSBOOT DUMPBUG parameter must be 1 (the default is 1).

Examples of How to Cause System Failures
The following examples show the sequence of commands needed to cause
a system failure on each type of VAX processor. On most processors, the
console command file CRASH.COM or CRASH.CMD performs these steps
for you.

EXAMPLES
□

$ I CTRL/P I
»>
»>
»>
»>
»>
»>

H
E PSL
E/I/N:4 0
D PC FFFFFFFF
D PSL IFOOOO
C

The preceding example shows how to cause a system failure on a VAX 11
/725 or a VAX 11/730. CTRL/P automatically halts the processor.
S

) I CTRL/P I
»>
»>
»>
»>
»>
»>
»>
»>

H
E P
E/I 0
E/I +
E/I +
E/I +
D/G F FFFFFFFF
D P IFOOOO

»> c
The preceding example shows the steps needed to cause a system failure on a
VAX 11/750. On these processors, the HALT command is a NOP; a CTRL/P
automatically halts the processor.
a

I CTRL/P I

»> HALT
HALTED AT 80008A89
»> EXAMINE PSL
00000000
»> EXAMINE/INTERN/NEXT:4 0
I
I
I
I
I

00000000
00000001
00000002
00000003
00000004

80008A89
00000000
00000000
00000000
80161E00

»> DEPOSIT PC = -1
»> DEPOSIT PSL = IFOOOO
»> CONTINUE
FATAL BUG CHECK, VERSION * X2M9 INVEXCEPTN, Exception while above ASTDEL or on interrupt stack
CURRENT PROCESS * NULL
REGISTER DUMP
RO = OIF

SDA-27

11/782, VAX 11/785, or a VAX 11/780. Note that the value place
PC, IFOOOO, sets the processor-access mode to kernel and the IPL t
Q

$ I CTRL/P I
PC = 80008B1F
»> D P IFOOOO
»> E P
OOIFOOOO
»> D/G F FFFFFFFFF
»> C

♦♦♦♦ FATAL BUG CHECK, VERSION =4.4 INVEXCEPTN, Exception while above ASTDEL or on interrupt s
CURRENT PROCESS - NULL
REGISTER DUMP

The preceding example shows the steps needed to cause a system
on a VAX 11/8200. On these processors, the HALT command is a
CTRL/P automatically halts the processor.
S

$ I CTRL/P I
»>
»>
»>
»>

»>
»>
»>

»>
»>

»>
»>
»>
»>

OCRASH
SET QUIET OFF
SET ABORT OFF
HALT
CPU stopped, INVOKED BY CONSOLE (CSM code 11)
PC 80008B1F
UNJAM
E PSL
U PSL 00000000
E/I/N:4 0
I 00 80000C40
I 01 00000000
I 02 00000000
I 03 00000000
I 04 00000000
E SP
G OE 80000C40
E/vir/next :40 Q
P 04206840 00000000
P 04206844 00000000

P 0420693C 00000000
P 04206940 00000000
D PC FFFFFFFF
D PSL IFOOOO
SET ABORT ON
SET QUIET ON

♦♦♦♦ FATAL BUG CHECK, VERSION = X4.4 INVEXCEPTN, Exception while above ASTDEL or on interrupt
CURRENT PROCESS NULL
REGISTER DUMP

The preceding example shows how to cause a system failure on a V
or VAX 8650.

SDA-28

PC = 8001911C
»> (DCRASH
!
! COMMAND PROCEDURE TO FORCE VMS BUGCHECK VIA ACCESS VIOLATION
!

SET VERIFY
SET CPU CURRENT.PRIMARY
!SELECT PRIMARY
EXAMINE PSL
!DISPLAY PSL
M 00000000 00420008
EXAMINE/I/NEXT 4 0
I 00000000 7FFE7DC8
I 00000001 7FFE9618
I 00000002 7FFEDE00
I 00000003 0000F39C
I 00000004 80873400
DEPOSIT PC FFFFFFFF
!SET PC=-1 TO FORCE ACCVIO
DEPOSIT PSL 41F0000
!SET IPL=31, INTERRUPT STACK
CONTINUE
!EXECUTE FROM PC=>1
*♦♦♦ FATAL BUG CHECK. VERSION = X4.3 INVEXCEPTN, Exception while above ASTDEL
CURRENT PROCESS = STARTUP
REGISTER DUMP
RO = OOOOOOIF

The preceding example shows how to cause a syste

System Dump Analyzer
Commands

COMMANDS

SDA-30

The commands described in the following section can be used in analyzing a
system dump or the running system.

System Dump Analyzer
@ (Execute Procedure)

@ (Execute Procedure)
Causes SDA to execute SDA commands contained in a file. Use this
command to execute a set of frequently used SDA commands.

FORMAT
command
parameter

@ file-spec
file-spec
The name of a file that contains the SDA commands to be executed. The
default file type is COM.

EXAMPLE
SDA> ©USUAL

The execute-procedure command shown previously carries out the SDA
commands contained in the file USUAL.COM, shown following.
SET OUTPUT LASTCRASH.LIS
SHOW CRASH
SHOW PROCESS
SHOW STACK
SHOW SUMMARY
EXIT

This command procedure makes the file LASTCRASH.LIS the destination
for output generated by subsequent SDA commands. Next, the command
procedure sends information on the crash, the process, the stacks, and a
summary of information to that file. Then it exits from the utility.
The procedure need not exit from the utility at the end its execution. To
continue using SDA interactively after the execution of a command procedure,
omit the EXIT command from the file.

SDA-31

System Dump Analyzer
ATTACH

ATTACH
Switches control of your terminal from your current process to
another process in your job.

FORMAT

ATT AC H process—name

command
parameter

process—name

command
qualifier

/PARENT

The name of the process to which you want to transfer control.

This qualifier specifies that control of your terminal is to be switched to the
parent process of your current process. If you specify this qualifier, do not
specify the process_name parameter in the ATTACH command.

EXAMPLES
□

SDA> ATTACH/PARENT

The ATTACH command attaches the terminal to the process that is the parent
of your current process.
B

SDA> ATTACH DUMPER

The ATTACH command attaches the terminal to the process that is named
DUMPER.

SDA-32

System Dump Analyzer
COPY

COPY
Copies the contents of the dump file to another file.

FORMAT
command
parameter

COPY output-file-spec
output- file-spec
The name of the device, directory, and file to which SDA copies the dump
file. The default file specification is SYS$DISK:[default-dir]filename.DMP. You
must supply the name of the file.

DESCRIPTION Each time the system fails, the system copies all of physical memory

and the hardware context of the current process into the file
SYS$SYSTEM:SYSDUMP.DMP (or the paging file), overwriting the
contents of that file. To preserve a crash dump, you must use the COPY
command to copy the contents of this file into another file. The contents of
SYSDUMP.DMP are not affected by execution of the COPY command.
The command procedure SYSTARTUP.COM should include this command to
ensure that a copy of the dump file is made each time the system fails.
If the paging file was used as a dump file instead of SYSDUMP.DMP, the
pages of the paging file that contain the dump information are not available
for paging until they are explicitly released. The COPY command releases
the dump pages in the paging file so that they are available for system paging
if process privilege has been set to change-mode-to-kemel (CMKRNL). If
CMKRNL privilege has not been set, the copy operation succeeds but the
blocks used by the dump in the paging file are not released. Note that once
the COPY command has released the dump pages for paging use, the dump
information in these pages may be lost. Subsequent dump analysis should
be carried out on the copy of the dump file that was specified in the COPY
command.

EXAMPLE
SDA> COPY SYS$CRASH:SAVEDUMP

The COPY command copies the dump file into the file
SYS$CRASH:SAVEDUMP.DMP.

SDA-33

System Dump Analyzer
DEFINE

DEFINE
Assigns a value to a symbol.

FORMAT

DEFINE[/KEY] symbol[=] expression [/qualifier...]

command

symbol

paranriGtGrS

The name you want to give the symbol. The symbol name can contain from
1 to 31 alphanumeric characters. See Section 6.2.5 for a discussion of SDA
symbols.
If used with the /KEY qualifier, this parameter is the name of the terminal
key to be defined. A list of the keys you can define, and their names, follows:
Key name

Key designation

PF1

LK201, VT100, VT52 Red

PF2

LK201, VT100, VT52 Blue

PF3

LK201, VT100, VT52 Black

PF4

LK201, VT100

KP0,...,KP9

Keypad 0-9

PERIOD

Keypad period

COMMA

Keypad comma

MINUS

Keypad minus

ENTER

Keypad ENTER

Up arrow

DOWN

Down arrow

LEFT

Left arrow

RIGHT

Right arrow

LK201 Find

LK201 Insert Here

LK201 Remove

LK201 Select

LK201 Prev Screen

LK201 Next Screen

HELP

LK201 Help

LK201 Do

F7.F20

LK201 Function keys

When you define some keys as SDA commands, you must press CTRL/V
before those keys to execute the commands. This is due to the escape
sequences these keys generate, and the way the terminal driver handles those
escape sequences. The following keys, when defined as SDA commands,
must be preceded by a CTRL/V.

SDA-34

System Dump Analyzer
DEFINE

Key Name

Key Designation

LEFT

Left arrow

RIGHT

Right arrow

F7.F14

LK201 function keys

expression
An expression that defines the value of the symbol. See Section 6.2 for a
discussion of SDA expressions.
When you use the /KEY qualifier, this parameter is the SDA command the
key is to be defined as.

command
qualifiers

/[NOJECHO
Determines whether the equivalence string is displayed on the terminal screen
after the defined key has been pressed. The /NOECHO qualifier functions
only with the /TERMINATE qualifier. The default is /ECHO.

/[NO]IF-STATE=(state-name,...)
Specifies a list of one or more states, one of which must be in effect for the
key definition to be in effect. The state name is an alphanumeric string. If
you omit the /IF_STATE qualifier or use /NOIF_STATE, the current state is
used. States are established with the /SET_STATE qualifier. If you specify
only one state name, you can omit the parentheses. By including several state
names, you can define a key to have the same function in all the specified
states.

/KEY
Causes a key, rather then a symbol, to be defined. If you use this qualifier,
the symbol parameter must be the name of a key on your terminal keyboard,
and the expression parameter must be the SDA command that is to be
executed when the key, followed by carriage return, is pressed.

/SET—STATE=state-name
Causes the key being defined to cause a key state change rather than
executing an SDA command. Instead of the name of a terminal key, the
expression parameter must be the name of a key state. The key state is any
name that you want to define. For example, you can define the PFl key to
set the state to gold and use the /IF_STATE=GOLD qualifier to allow two
definitions for the other keys, one in the gold state and one in the not-gold
state. An example of this sort of multiple key definition is shown in example
seven for this command.

/[NOJTERMINATE
Causes the key definition to include termination of the command, which
causes SDA to execute the command when the defined key is pressed.
Therefore, you do not have to press the RETURN key after you press the
defined key if the /TERMINATE qualifier is specified.

SDA-35

System Dump Analyzer
DEFINE

DESCRIPTION

SDA evaluates the expression, then assigns its value to the symbol. If the
symbol is already defined, the new value replaces the old one. The symbol
remains defined until you exit from SDA.
Both the DEFINE and EVALUATE commands perform computations in order
to evaluate expressions. DEFINE adds symbols to the SDA symbol table but
does not display the results of the computation. EVALUATE displays the
result of the computation but does not add symbols to the SDA symbol table.

EXAMPLES
Q

SDA> DEFINE BEGIN = 80058E00
SDA> DEFINE END = 80058E60
SDA> EXAMINE BEGIN:END

In the preceding example, DEFINE defines two addresses, called BEGIN and
END. These symbols serve as reference points in memory, defining a range of
memory locations between which the EXAMINE command can examine.
B

SDA> DEFINE NEXT = OPC
SDA> EXAMINE/INSTRUCTION NEXT
00000464:
MOVL 6(R1). R3

Symbol NEXT defines the address contained in the program counter. SDA
represents nonprinting characters by a period (.) and puts quotation marks
around ASCII text. Refer to Section 6.2.5 for a discussion of SDA symbols.
B

SDA> DEFINE VEC SCH$GL_PCBVEC

This command assigns the value of a global symbol, SCH$GL-_PCBVEC, to
the symbol VEC. Now you can use the symbol VEC to access the memory
location or value represented by the global symbol.
2

SDA> DEFINE COUNT = 4
SDA> DEFINE RESULT = COUNT * COUNT
SDA> EVALUATE RESULT
Hex = 00000010
Decimal = 16

The preceding example assigns symbol COUNT the value 4 and then uses
the symbol in an arithmetic expression.
S5DA> DEFINE/KEY PFl "SHOW STACK"
SDA> IPFI 1 SHOW STACK 1 RETURN 1
Current operating stack
Current operating stack (KERNEL):

SP *>

7FFE8DD4
7FFE8DD8
7FFE8DDC
7FFE8DE0
7FFE8DE4
7FFE8DE8
7FFE8DEC
7FFE8DF0

00001703
80127920
00000000
00000000
00000000
00000000
7FF743E4
7FF743CC

SGN$C_MAXPGFL+703

7FFE8DF4
7FFE8DF8
7FFE8DFC

8000E646
7FFEDE96
03C00000

EXE$CM0DEXEC+1EE
SYS$CMKRNL+006

The preceding example shows the DEFINE/KEY command being used to
define PFl as the SDA SHOW STACK command. When the PFl key is
pressed, SDA displays the command and waits for a carriage return to be
typed.

SDA-36

System Dump Analyzer
DEFINE

SDA> DEFINE/KEY/TERMINATE PFl "SHOW STACK"
SDA> IPFlI SHOW STACK
Current operating stack
Current operating stack (KERNEL):
7FFE8DD4
7FFE8DD8
7FFE8DDC
7FFE8DE0
7FFE8DE4
7FFE8DE8
7FFE8DEC
7FFE8DF0

00001703
80127920
00000000
00000000
00000000
00000000
7FF743E4
7FF743CC

SGN$C_MAXPGFL+703

7FFE8DF4
7FFE8DF8
7FFE8DFC

8000E646
7FFEDE96
03C00000

EXE$CM0DEXEC+1EE
SYS$CMKRNL+006

SP =>

The preceding example shows the DEFINE/KEY command being used
to define PFl as the SDA SFIOW STACK command. The use of the
/TERMINATE qualifier causes SDA to execute the SHOW STACK command
without waiting for a carriage return to be typed.
Q

SDA> DEFINE/KEY/SET_STATE*"GREEN" PFl ""
SDA> DEFINE/Kp/TERMINATE/IF.STATE^GREEN PF3 "SHOW STACK"
SDA> |PFl||PF3| SHOW STACK
Current operating stack
Current operating stack ([KERNEL):

SP =>

7FFE8DD4
7FFE8DD8
7FFE8DDC
7FFE8DE0
7FFE8DE4
7FFE8DE8
7FFE8DEC
7FFE8DF0

00001703
80127920
00000000
00000000
00000000
00000000
7FF743E4
7FF743CC

SGN$C_MAXPGFL+703

7FFE8DF4
7FFE8DF8
7FFE8DFC

8000E646
7FFEDE96
03C00000

EXE$CM0DEXEC+1EE
SYS$CMKRNL+006

The preceding example shows the definition of two keys. PFl is defined as a
key that sets a command state GREEN. The trailing pair of quotation marks
are required syntax, indicating that no command is to be executed when this
key is pressed.
The next line shows the definition of PF3 as the SHOW STACK command.
The use of the /IF_STATE qualifier makes the definition valid only when the
command state is GREEN when PF3 is pressed, which means that PFl must
be pressed first. The use of the /TERMINATE qualifier causes the command
to execute as soon as the PF3 key is pressed. SDA does not wait for RETURN
to be pressed to terminate the command line.

SDA-37

System Dump Analyzer
EVALUATE

EVALUATE
Computes and displays the value of the specified expression in both
hexadecimal and decimal. If the expression is equal to the value of a
symbol in the SDA symbol table, that symbol is displayed. A finite
number of such symbols is displayed by default. If no symbol with
this value is known, the next lower valued symbol is displayed with
an appropriate offset if the offset is small enough for the selected
symbol to be considered useful.
Alternative evaluations of the expression are available with the use
of the qualifiers defined for this command.

FORMAT

EVALUATE expression

command
parameter

The SDA expression to be evaluated. Section 6.2 defines SDA expressions.

command
qualifiers

expression
/CONDITION-VALUE
Displays the message that the $GETMSG system service obtains for the value
of the expression.

/PSL
Evaluates the specified expression in the format of a processor status
longword.

/PTE
Interprets and displays the expression as a page table entry (PTE). The
individual fields of the PTE are separated and an overall description of the
PTE's type is provided.

/SYMBOLS
Specifies that all symbols that are known to be equal to the evaluated
expression are to be displayed.

EXAMPLES
Q

SDA> EVALUATE -1
Hex = FFFFFFFF

Decimal = -1

The preceding example shows how the EVALUATE command evaluates a
numeric expression and displays the value of that expression in hexadecimal
and decimal notation.

SDA-38

System Dump Analyzer
EVALUATE

SDA> EVALUATE 1
Hex = 00000001

Decimal = 1

ACP$V_SWAPGRP
ACP$V_WRITECHK
EVT$_EVENT

The preceding example shows how the EVALUATE command evaluates a
numeric expression and displays the value of that expression in hexadecimal
and decimal notation. The preceding example also shows the symbols that
have the displayed value. A finite number of symbols are displayed by
default.
S

SDA> DEFINE TEN = A
SDA> EVALUATE TEN
Hex = OOOOOOOA
Decimal = 10

EXE$V_FATAL_BUG
SGN$C_MINWSCNT
TEN

The preceding example shows the definition of a symbol named TEN. The
EVALUATE command then shows the value of the symbol.
Note that A, the value assigned to the symbol by the DEFINE command,
could be a symbol. When SDA evaluates a string that can be either a symbol
or a hexadecimal numeral, it first searches its symbol table for a definition of
the symbol. If SDA finds no definition for the string, it evaluates the string as
a hexadecimal number.
□

SDA> EVALUATE (((TEN ♦ 6) + (-1/4)) + 6)
Hex = 00000042
Decimal = 66

The preceding example shows how SDA evaluates an expression of several
terms, including symbols and rational fractions. SDA evaluates the symbol,
substitutes its value in the expression, and then evaluates the expression.
Note that the fraction -1/4 is truncated to 0. See Section 6.2 for a detailed
discussion of expressions.
B

SDA> EVALUATE/CONDITION 80000018
%SYSTEM-W-EXQUOTA, exceeded quota

The preceding example shows the output of an EVALUATE/CONDITION
command.
B

SDA> EVALUATE/PSL 04080009
CMP TP FPD IS CURMOD PRVMOD IPL DV FU IV T N Z V C
0
0 0
1 KERN
KERN
08 0 0 001001

The preceding example shows the output of an EVALUATE/PSL command.
SDA interprets the entered value 04080009 as though it were a program
status longword and displays the resulting field values in that longword.

SDA-39

System Dump Analyzer
EVALUATE

131

SDA> EVALUATE/PTE ABCDFFEE

28127

24123

20119

16116

12111

817

I
111

0 10 1

10 I —I

Vld

Prot= EW

1 1
0wn=U

I--I 01
W

ODFFEE
Page Frame Number

Page is Active and Valid

The preceding example shows the output of an EVALUATE/PTE command,
which shows how SDA displays the page table entry and labels the fields. It
also describes the page status.

SDA-40

System Dump Analyzer

EXAMINE

EXAMINE
Displays the contents of a location or range of locations in physical
memory. You can use location parameters to display specific
locations or use qualifiers to display entire process and system
regions of memory.

FORMAT
command
parameters

EXAM N E [/qualifierf,...]] [parameter]

location
The location in memory to be examined. The default value of this parameter
is initially 0, and subsequently is 4 plus the last address examined.
Subsequent default addresses are affected by the /INSTRUCTION qualifier.

m:n
A range of locations to be examined, from m to n.

m;n
A range of locations to be examined, starting at m and continuing for n bytes.

command
qualifiers

/ALL
Examines all the locations in the program and control regions and parts of the
writable system region, displaying the contents of memory in hexadecimal
longwords. Do not specify parameters when you use this qualifier.

/CONDITION-VALUE
Examines the specified longword, displaying the message the $GETMSG
system service obtains for the value in the longword.

/INSTRUCTION
Translates the contents of the specified range of memory locations into
MACRO-instruction format. If more than 16 bytes are specified in the range,
/INSTRUCTION processing may skip some bytes at the beginning of the
range to ensure that SDA is properly synchronized with the start of each
instruction. This synchronization may be overridden by specifying the
/NOSKIP qualifier with the /INSTRUCTION qualifier.
The length of the instruction displayed varies according to the opcode and
addressing mode. If SDA cannot decode a memory location, it issues the
following message.
y.SDA-E-NOINSTRAN. cannot translate instruction

When you use this qualifier with the EXAMINE command, the default
address parameter is initially 0. SDA calculates subsequent default addresses
by adding the length of the last instruction, including all operands, to the last
address examined.

SDA-41

System Dump Analyzer
EXAMINE

/NOSKtP
Causes the EXAMINE/INSTRUCTION command not to skip any bytes
in the range when translating the contents of memory into VAX MACRO
instructions. The /NOSKIP qualifier causes the execution of the
/INSTRUCTION qualifier by default.

/NOSUPPRESS
Inhibits the suppression of zeros when displaying memory with one of the
following qualifiers: /ALL, /PO, /PI, /SYSTEM.

/PO
Displays the entire program region for the default process. Do not specify
parameters when you use this qualifier.

/PI
Displays the entire control region for the default process. Do not specify
parameters when you use this qualifier.

/PSL
Examines the specified longword, displaying its contents in the format of a
processor status longword. This qualifier must precede any parameters used
in the command line.

/PTE
Interprets and displays the specified longword as a page table entry (PTE).
The display separates individual fields of the PTE and provides an overall
description of the PTE's type.

/SYSTEM
Prints portions of the writable system region. Do not specify parameters
when you use this qualifier.

/TIME
Examines the specified quadword, displaying its contents in the format of a
system-date-and-time quadword.

DESCRIPTION

The EXAMINE command displays the contents of memory and registers. The
following sections describe how to use this command.

Examining Locations
Use the location parameter to examine a specific location. A location can be
represented by any valid SDA expression.
To examine a range of locations, designate starting and ending locations
separated by a colon, for example, G40:G200; or specify a location and a
length, in bytes, separated by a semicolon, for example, G400;16.
If a series of virtual addresses does not exist in physical memory, SDA prints
a message specifying the range of addresses that were not translated:
SDA> EXAMINE 100:220

SDA-42

System Dump Analyzer
EXAMINE

Virtual locations 00000100 through OOOOOIFF are not in physical memory
013001 lA 012001 IB 013001 IE 011001 IF
01200107 02300510 04310216 04210218
01100103 01100104 01200105 01200106

.0.0.
1... 0... .
.

00000200
00000210
00000220

The contents of addresses 100 through IFF are nonexistent, and are so labeled
in the message. Addresses 200 through 220 do exist, and SDA displays their
contents. Note that the ASCII representation of the contents of memory reads
from left to right, but the hexadecimal representation reads from right to left.
Thus, for example, the byte at 210 contains ..!. (unprintable ASCII characters
are represented by periods), which is 04210218 (hexadecimal).
If a range of virtual locations contains only zeros, SDA prints the message:
Zeros suppressed from loci to loc2

SDA initially sets the current location to zero in the program region (PO) of
either the process that was executing at the time the system failed (if you are
examining a crash dump), or your process (if you are examining the running
system). To examine memory locations of other processes, you must use the
SET PROCESS command.
When you use the EXAMINE command to look at a location, SDA displays
the location, in symbolic notation (symbolic name plus offset) if possible, and
its contents, in hexadecimal and ASCII formats.

Decoding Locations
You can translate the contents of memory locations into MACRO-instruction
format by using the /INSTRUCTION qualifier. This qualifier causes SDA
to display the location in symbolic notation (if possible) and its contents in
instruction format. The operands of decoded instructions are also displayed
in symbolic notation.
If the specified range of locations does not begin on an instruction boundary,
SDA skips bytes until it locates the next valid instruction, and issues the
message:
y,SDA-W-INSKIPPED, unreasonable instruction stream - n bytes skipped

In this message, n is the number of bytes that SDA could not translate.
You can use the SHOW STACK command to interpret the contents of memory
as symbolic addresses. See the description of the SHOW STACK command
for details.

Examining Memory Regions
You can display an entire region of virtual memory by using one or more
qualifiers with the EXAMINE command.
SDA displays six columns of information. The first four columns contain the
contents of memory, in hexadecimal. Each column represents a longword.
The fifth column contains the ASCII value of each byte in the longwords of
the first four columns. Where the ASCII character that corresponds to the
value contained in a byte is not a printing character, SDA prints a period
character (.) in column 5.
The sixth column contains the address of the first, or rightmost, longword in
each line. This address is also the address of the first, or leftmost, character is
the ASCII representation of the longwords. Thus, you read the dump display
from right to left, and the ASCII display from left to right. See the following
example for an illustration.

SDA-43

System Dump Analyzer
EXAMINE

Examining the PSL
To examine the processor-status longword, use the /PSL qualifier with the
EXAMINE command.

EXAMPLES
□

SDA> EXAMINE/SYSTEM
System Region Memory
00040039 8FBC0010 00040038 8FBC0010

_8.9...

800000000

The preceding example shows only the first two lines of the display generated
by the EXAMINE/SYSTEM command. Note that in the dump, the fifth byte
from the right contains the value 38. The ASCII value of 38, the character 8,
is represented in the fifth character from the left in column 5.
Likewise, the thirteenth byte from the right in the dump columns contains
the value 39. The ASCII value of 39 is 9, and 9 is represented in the ASCII
column as the thirteenth character from the left.
B

SDA> EXAMINE/PSL G1268
CMP TP FPD IS CURMOD PRVMOD IPL DV FU IV T N Z V C
1
0 0
0 KERN
KERN
00 0 1 011100

The preceding example shows the display produced by the EXAMINE/PSL
command. The address of the longword examined is 80001268.

SDA-44

System Dump Analyzer
EXIT

EXIT
Performs two functions: it exits from an SDA display, and it exits
from the utility.

FORMAT

EXIT

command
parameters

None.

command
qualifiers

None.

DESCRIPTION

If SDA is displaying information on a video display terminal such as a VTIOO,
and if that display is more than one page of information, SDA displays the
following message, called a screen overflow prompt, each time it reaches the
bottom of a page:
Press RETURN for more.
SDA>

If you want to discontinue the current display at this point, type EXIT. (On
printing terminals, SDA does not display a prompt at the bottom of each
page.) If you want SDA to execute another command at this point, type that
command. SDA discontinues the display as if you typed EXIT, and then
executes the command you typed.
To stop SDA, type EXIT in response to the SDA> prompt.

SDA-45

System Dump Analyzer
FORMAT

FORMAT
The FORMAT command displays a formatted list of the contents of
a block of memory. It attempts to

FORMAT
command
parameter

•

Characterize a range of locations as a systemwide data block

•

Assign a symbol to each item of data within the block

•

Display all the data within the block

FORMAT [/qualifier] location

location
The location of the beginning of the data block. The location can be given as
any valid SDA expression.

command
qualifier

/TYPE=block-type

DESCRIPTION

The FORMAT command causes SDA to examine the byte at location+10
(decimal) or location+A (hexadecimal), which contains the type of the data
block in most systemwide data blocks. If this byte contains a valid block
type, SDA checks the next byte, at location+11, for the secondary block type.
If byte 10 does not contain a valid block type, no further action is taken.

This qualifier indicates the symbolic prefix that corresponds to the type of
block structure you want to format. This qualifier accepts as parameters the
prefix of any VAX/VMS control block. See the READ command for a list of
the symbol-table files supplied with the VAX/VMS operating system.

When SDA has determined the type of block, it tries to find the symbols that
correspond to that type of block.
If SDA cannot find the symbols associated with the block type you have
indicated or that it has found in the the block you specified, it issues the
message:
No "block-type" symbols found to format this block

Not every data block contains its type byte at offset 10. If this byte is absent
or contains information other than a block type, or the byte does not contain
a valid block type, SDA produces the message:
Invalid block type in specified block

To format such a block, you must retype the FORMAT command, using the
/TYPE= qualifier to designate a block type, or use the READ command to
have SDA read the file that contains the definitions of the symbols; and then
retype the FORMAT command.
The display produced by the FORMAT command shows, from left to right,
the virtual address of each item within the block, its symbolic name, and its
hexadecimal representation.

SDA-46

System Dump Analyzer
FORMAT

EXAMPLE
SDA> read SYS$SYSTEM:SYSDEF.STB
SDA> format 80OB81F0
800B81F0
UCB$L_FQFL
UCB$L_RQFL
UCB$W_MB_SEED
UCB$W_UNIT_SEED
800B81F4
UCB$L_FQBL
UCB$L_RQBL
800B81F8
UCB$W_SIZE
800B81FA
UCB$B_TYPE
800B81FB
UCB$B_FIPL
800B81FC
UCB$L_ASTQFL
UCB$L_FPC
UCB$T_PARTNER
800B8200
UCB$L_ASTQBL
UCB$L_FR3
800B8204
UCB$L_FIRST
UCB$L_FR4
UCB$W_MSGMAX
UCB$W_MSGCNT

80000F10

800026A8
OOEO
10
08
800F80E0

8002CF80
8002CA00

The FORMAT command displays the data structure that begins at 800B81F0, a
UCB. SDA uses the symbols in SYSDEF.STB to provide the names displayed
next to each address displayed. If the field has more than one symbolic
name, all such names are displayed. Thus, the field that starts at 800B8204
has three designations, UCB$L—FIRST and UCB$L—FR4, alternative names
for the longword, and the two subfields, UCB$W_MSGMAX and UCB$W—
MSGCNT.
The contents of each field appears to the right of the symbolic name of the
field. Thus, the contents of UCB$L—FIRST are 8002CA00.

SDA-47

System Dump Analyzer
HELP

HELP
Displays information about the SDA utility, its operation, and the
format of its commands. HELP has three command parameters. If
you do not specify a parameter, HELP gives a brief description of
SDA operations and displays SDA commands.

FORMAT

HELP

command
parameters

Specifies the command for which you need information.

[parameter]

command-name
EXPRESSION
Prints a description of SDA expressions.

OPERATION
Describes how to operate SDA at your terminal and by means of the sitespecific startup procedure.

command
qualifiers

SDA-48

None.

System Dump Analyzer
READ

READ
Causes SDA to read the global symbols contained in the specified
object module and to add those symbols to the SDA symbol table.
SDA extracts no local symbols from the object module.

[/qualifierf,...]] filespec

FORMAT

READ

command
parameter

filespec
S YS$DISK:[default-dirjfilename. stb
The name of the device, directory, and file that contains the object module
from which you want to copy global symbols. The object module file can
be the output of a compiler or assembler, the output generated by the linker
qualifier /SYMBOL __TABLE, or one of the object module files provided by
VAX/VMS. Those files are the following:
File

Contents

DCLDEF.STB

The symbols for the DCL command language interpreter.

IMGDEF.STB

Symbols for the image activator.

NETDEF.STB

Symbols that define DECnet data structures.

RMS.STB

Global symbols for VAX RMS.

RMSDEF.STB

Symbols that define RMS internal and user data structures. Also,
contains the RMS$_xxx completion codes.

MP.STB

Symbols for multiprocessor code.

SCSDEF.STB

Symbols that define data structures for system communications
services.

SYSDEF.STB

Symbols that define system data structures, including the I/O
database.

command
qualifier

/RELOCATE=expression

DESCRIPTION

The READ command is useful in those cases where the symbols needed
are defined in modules that are compiled and linked separately from the
VAX/VMS executive.

Add the value of expression to the value of each symbol in the symbol-table
file to be read. This qualifier is useful for examining images that are position
independent and are loaded at a base of zero.

SDA-49

System Dump Analyzer
READ

EXAMPLES
□

SDA> READ SYStSYSTEM:SYSDEF.STB
SDA>

The READ command causes SDA to add all the global symbols in
SYS$SYSTEM:SYSDEF.STB to the SDA symbol table. Such symbols are
useful when you use the FORMAT command, for example.
E

SDA> READ/RELOCATE-MP SYSISYSTEM:MP.STB
SDA>

This READ command causes SDA to read the file that contains the symbols
defined for the code that supports multiprocessors. The /RELOCATE qualifier
causes the values of those symbols to be the sum of the value of the symbol
in the file and the value of symbol MP, the address of the beginning of the
multiprocessor code.

SDA-50

System Dump Analyzer
REPEAT

REPEAT
Repeats execution of the last command issued. On terminal devices,
the KPO key performs the same function as the REPEAT command.

FORMAT

REPEAT

command
parameters

None.

command
qualifiers

None.

DESCRIPTION

The REPEAT command is useful for stepping through a linked list of data
structures, or for examining a sequence of memory locations.

EXAMPLE
SDA> FORMAT GIOEO
8000010E0 UCB$L_FQFL
UCB$L_FQBL

SDA> IkPOI
SDA> FORMAT GIOEO
8000010E0 UCB$L_FQFL
UCB$L_FQBL

80002428

The FORMAT command displays a UCB. The REPEAT command causes SDA
to display the FORMAT command, then reexecute it, displaying the contents
of the UCB once more.

SDA-51

System Dump Analyzer
SEARCH

SEARCH
Scans a range of memory locations for all occurrences of a longword
value. SEARCH displays each location as each value is found.

FORMAT
command
parameters

range[=]expression

range
The range of memory locations that you want SDA to search. You can specify
a range as a starting location and an ending location, separated by a colon
:), or as a location and a length, in bytes, separated by a semicolon (;).

(

expression
An expression. SDA evaluates this expression and searches the range of
memory for that value. SDA only searches for values that are aligned on
longword boundaries. For a definition of SDA expressions, see Section 6.2.

command
qualifier

/LENGTH=length—specifier
The /LENGTH qualifier specifies the size of the expression value to be used
for successful matching during searches of memory. The possible values of
this qualifier are:
•

LONGWORD — specifies that the expression for which to search is 4
bytes in length. This is the default value.

•

WORD — specifies that the expression for which to search is 2 bytes in
length.

•

BYTE — specifies that the expression for which to search is 1 byte in
length.

/STEPS=step—factor
The /STEPS qualifier controls the granularity of searching through the
specified memory range. As each comparison of memory occurs, the value
of this qualifier determines the next memory location to be searched. The
possible step factors are as follows:

•
•
•
•

SDA-52

QUADWORD — specifies a step factor of 8 bytes.
LONGWORD — specifies a step factor of 4 bytes. This is the default
value for the /STEPS qualifier.
WORD — specifies a step factor of 2 bytes.
BYTE — specifies a step factor of 1 byte.

Match at 800B8210
SDA>

The SEARCH command found the value 0060068 in t
800B8210.
B

SDA> SEARCH/STEPS*BYTE 80000000;1000 6
Searching from 80000000 to 80001000 in BYTE steps for 00000006...
Match at 80000A99
SDA>

The SEARCH command found the value 00000006 in
80000A99.
B

SDA> SEARCH/LENGTH*WORD 80000000; 2000 6
Searching from 80000000 to 80002000 in LONGWORD steps for 0006...
Match at 80000064
Match at 800001EC
Match at 800012AC
Match at 800012B8
SDA>

The SEARCH command found the value 0006 in the l
80000054, 800001EC, 800012AC, and 800012B8.

System Dump Analyzer
SET LOG

SET LOG
Sends output from SDA to both your terminal and to a log file.

FORMAT
command
parameter

SET LOG

file-spec

file-spec
The name of the file in which you want SDA to log your commands and their
output. The default device is SYS$OUTPUT.

command
qualifiers

None.

DESCRIPTION

The SET LOG command sends your commands and the output they produce
to a log file. Your commands and the resulting displays are still displayed on
your terminal. Note that any output redirected to another file by means of
the SET OUTPUT command does not appear in the log file.

SDA-54

System Dump Analyzer
SET NOLOG

SET NOLOG
Stops SDA from logging your commands and their output.

FORMAT

SET NOLOG

command
parameters

None.

command
qualifiers

None.

SDA-55

System Dump Analyzer
SET OUTPUT

SET OUTPUT
Redirects the SDA output to the file or device of your choice.

FORMAT

SET OUTPUT file-spec

command
parameter

file-spec
The name of a device or the specification of a file to which you want SDA to
send the output generated by your commands. The default file specification
is SYS$DISK:[default-dir] SYSDUMP.LIS.

DESCRIPTION When you use the SET OUTPUT command to send the SDA output to a

file or device, SDA continues displaying the SDA commands that you type
but sends the output generated by those commands to the file or device you
specified.
If you finish directing SDA commands to an output file and wish to return to
interactive display, issue the command SET OUTPUT TT.

If you use the SET OUTPUT command to send the SDA output to a file, SDA
remembers all the commands you use to show information until you either
use another SET OUTPUT command or exit from the utility. SDA then builds
a table of contents that identifies the displays you selected and places the
table of contents at the beginning of the output file.

EXAMPLE
SDA> SET OUTPUT DUMPDISK:[CURRENT3SDA.TXT
SDA> SHOW CRASH
SDA> EXIT
$ TYPE DUMPDISK:[CURRENT3SDA.TXT

VAX/VMS 4.4 — System Dump Analysis

06-JAN-1986 16:22:29.13

Page 1

VAX/VMS 4.4 -- System Dump Analysis
System crash information

06-JAN-1986 15:22:29.13

Page 2

Time of system crash: 06-JAN-1986 15:21:53.38
Version of system: VAX/VMS VERSION X4.4
VAXcluster node name: REDDOG
Process currently executing: CRAWDAD
Current image file: $264$DUS0:[SYS4.SYSCOMMON.][SYSEXE]SDA.EXE;1
Current IPL: 0
(decimal)
General registers:
RO
R4
R8
AP
PSL

SDA-56

= 00000000
= 00000000
* 00000000
= 00000000
= 00000000

R1
R5
R9
FP

= 00000000
= 00000000
= 00000000
= 00000000

R2
R6
RIO
SP

=
*
*
=

00000000
00000000
00000000
00000000

R3
R7
Rll
PC

=
=
*
=

00000000
00000000
00000000
00000000

ICR
TODR
ACCS

= 00000000
= 00000000
= 00000000

ISP
KSP
ESP
SSP
USP

=
=
=
=
=

SBISTS = 00000000
SIL0CMP= 00000000
MAINT = 00000000

SBIERR = 00000000
TM0ADDRS=OOOOOOOO

00000000
00000000
00000000
00000000
00000000

VAX/VMS 4.4 -- System Dump Analysis
System crash information

06-JAN-1986 15:22:29.13

]

SBI silo contents:
00000000
00000000
00000000

00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000

The preceding example shows the SET OUTPUT co
output from the SHOW CRASH command to a file
disk DUMPDISK in directory [CURRENT]. The TYP
contents of the file that SDA generates.

System Dump Analyzer
SET PROCESS

SET PROCESS
The SET PROCESS command changes process context, making the
specified process the SDA current process.

FORMAT
command
parameter

command
qualifiers

SET PROCESS

[/qualifierf,...]] [name]

name
The name of the process to become the SDA current process. The name is a
string containing up to 15 uppercase alphabetic characters or numerals. The
dollar sign ($) and underscore (_) characters can be included in the string.
The name must be a quoted string if other than the foregoing characters are
included.

/INDEX=nn
The index into the system's list of software process control blocks (PCB).
Alternatively, this argument can be the process identification (EPID or PID)
longword, from which SDA extracts the correct index.

/SYSTEM
The system process control block. The system PCB and process header (PHD)
are dummy structures that are located in system space and contain the system
working set, global section table, global page table, and other systemwide
data.

DESCRIPTION

When you issue an SDA command, for example an EXAMINE command,
SDA displays the contents of memory locations in its current process. To
display any information about another process, you must change the current
process with the SET PROCESS command.
This command allows you to examine the data structures associated with any
process. The process specified by this command becomes the SDA current
process until you either use another SET PROCESS command or exit from
SDA.
When you invoke SDA to examine a system dump, the SDA current process
is the process that was executing when the system failed. If you invoke SDA
to examine the running system, the current process is your process.
SET PROCESS locates the information needed for the particular process but
produces no output.
You must specify one of the three SET PROCESS parameters and qualifiers,
or SDA generates a syntax error.

SDA-58

SDA> SHOW PROCESS
Process index: 0012
Process status:

Name: NETACP

00149001

PCB address
PHD address

RES.WAKEPEN.NOACNT.PHDRES.LOGIN
800F1140
80477200

JIB address
Swapfile disk address

801FDA00
OlOOOFOl

SDA> SHOW SUMMARY
Current process summary
Extended Indx Process name
DTn
rlU -28C00080 0000 NULL
28C00081 0001 SWAPPER
28C00483 0003 KLINGON
28C00085 0005 ERRFMT
28C00087 0007 OPCOM

Extended PID: 28C00092

Username

State Pri

KLINGON
SYSTEM
SYSTEM

COM
0 80002100 80001F88
HIB
16 800023C8 80002260
MWAIT 6 8010FEA0 803F8600
COM
10 800B6A10 8061DA00
LEF
7 800C7000 80227A00

SDA> SET PROCESS ERRFMT
SDA> SHOW PROCESS
Process index: 0006
Name: ERRFMT
Process status:
PCB address

00040001

PCB

PHD

Wkset
0
0
323
69
71

Extended PID: 28C00085

RES.PHDRES
800B6A10

JIB address

801E5C00

The first SHOW PROCESS command shows the curren
NETACP. The SHOW SUMMARY command shows the
processes that exist. The SET PROCESS command sets
ERRFMT, as shown by the second SHOW PROCESS co

System Dump Analyzer
SET RMS

SET RMS
The SET RMS command changes the options shown by the SHOW
PROCESS/RMS command.

FORMAT
command
parameter

SET RMS=opt/on
option
The list of RMS data structures to be shown by the SHOW RMS command.
The options are listed in the table that follows. You can suppress output for a
given option by preceding that option with NO.
The list can consist of one or more options. If the list contains more than
one option, the list must be in parentheses, and options must be separated by
commas.

ifi

The optional parameter
is an internal file identification. The default ifi is
all the files the current process has opened.

command
qualifiers
SDA-60

List-item

Meaning

ALL[:ifi]

All control blocks, the default

ASB

Asynchronous-save block

BDB

Buffer-descriptor block

BDBSUM

BDB summary page

BLB

Buffer-lock block

BLBSUM

Buffer-lock summary page

CCB

Channel-control block

FCB

File-control block

FWA

File work area

GBDSUM

GBD summary page

GBH

Global buffer's header

IDX

Index descriptor

IFAB[:ifi]

Internal FAB

IFB[:ifi]

Internal FAB

IRAB

Internal RAB

IRB

Internal RAB

RLB

Record-lock block

TRC

Global-buffer trace Information

WCB

Window-control block

Current list of options displayed by the SHOW RMS command

None.

command are the types of data structures that will be d
options not specified in the command will not be displa
options is that specified by the ALL parameter.

To add or delete an option from the current list to be d
having to specify the entire list, use the asterisk parame
more other options. The asterisk paramenter (♦) represe

EXAMPLES
□

SDA> SET RMS»(WCB.CCB.BDB.ASB)
SDA> SHOW PROCESS/RMS

Process index: 003C

Name: BIRDSONG

Extended PID: 212000BC

CCB Address: 7FFDAF40
80159960
00
02
0000

UCB:
STS:
AMOD:
IOC:

Executive
0.

WIND:

802A6080

DIRP:

00000000

SIZE:
TYPE:

0060
12

WCB Address: 802A6080
802B5B90
802B5B90
03
0001003C
0601
0001
00000001

WLFL:
WLBL:
ACCESS:
PID:
ACON:
NMAP:
STVBN:
VBN

RVN

96.

READ,WRITE
ORGUCB:
NOWRITE,WRITEAC,NOREAD
1.
FCB:
1.
RVT:

802B5B80
00000000

Starting LBN

Count

0002A6C7

173611.

80169960

0021

ASB Address: 7FF74600
ARGCNT:
FABRAB:
ERR:
SUC:

00
00000000
00000000
00000000

R6:
R7:
R8:
RIO:
Rll:

OOOOOOIE
00000003
OOOOllBC
7FF73608
7FFE0270

BID:
BLN:
STKLEN:
STKSIZ:

OD
2F
008C
002C

13.
47.
140.
44.

7FF74640
7FF74644
7FF74648
7FF7464C
7FF74660
7FF74654
7FF74668

7FF741A0
00000001
7FF74160
0000164E
80045D44
00000001
80045EDE

SGN$C.MAXPGFL+64E

BDB Address: 7FF737A8
FLINK:
BLINK:
FLGS:
USERS:
CACHE.VAL:
SIZE:
ADDR:
VBNSEQNO:
WKl:
REL.VBN:
VAL.VBNS:
JNLSEQ:
lOSB:

7FF74150
7FF73648
00
0000
00
2000
7FF74800
00000000
00000000
00
00
00000000
00000000
00000000

BID:
BLN:
0.
0.
8192.

0.
0.
00000000

BLB.PTR:
BUFF.ID:
NUMB:
VBN:
WAIT:
CURBUFADR:
PRE.CCTL:
POST.CCTL:
00000000 00000000

OC
14
00000000
0000
0000
00000000
00000000
00000000
00
00

12
20

0
0
0

BDB Address: 7FF74160
FLINK:
BLINK:
FLGS:
USERS:
CACHE.VAL:
SIZE:
ADDR:
VBNSEQNO:
WKl:
REL.VBN:
VAL.VBNS:
JNLSEQ:
lOSB:

7FF73648
7FF737A8
03
0000
00
2000
7FF76800
00000000
00000606
05
06
00000000
00000606
7FF77200

BID:
BLN:
VAL.DRT
0.
0.
8192.

6.
6.
00000000

BLB.PTR:
BUFF.ID:
NUMB:
VBN:
WAIT:
CURBUFADR:
PRE.CCTL:
POST.CCTL:
00000000 00000000

OC
14
00000000
0000
0200
00000001
00000000
7FF77200
00
00

12
20

0
512
1

The preceding example shows a SET RMS command used to se
data structures that the SHOW PROCESS/RMS command displ
subsequent SHOW PROCESS/RMS command displays the WCB
the BDB, and the ASB.
B

SDA>
SDA>

SET RMS*(*,N0ASB)
SHOW PROCESS/RMS

Process index: 003C

Neune: WILLING

Elxtended PID: 212000BC

CCB Address: 7FFDAF40
UCB:
STS:
AMOD:
IOC:

SDA-62

80169960
00
02
0000

Executive
0.

WIND:

802A6080

DIRP:

00000000

ACON:
NMAP:
STVBN:

0501
0001
00000001

NOWRITE, WRITEAC,NOREAD
FCB:
1.
1.
RVT:

802B5B80
00000000

VBN

RVN

Starting LBN

Count

0002A6C7

173511.

0021

33.

BDB Address: 7FF737A8
FLINK:
BLINK:
FLGS:
USERS:
CACHE.VAL:
SIZE:
ADDR:
VBNSEQNO:
WKl:
REL.VBN:
VAL.VBNS:
JNLSEQ:
lOSB:

7FF74150
7FF73648
00
0000
00
2000
7FF74800
00000000
00000000
00
00
00000000
00000000
00000000

BID:
BLN:
0.
0.
8192.

0.
0.
00000000

BLB.PTR:
BUFF.ID:
NUMB:
VBN:
WAIT:
CURBUFADR:
PRE.CCTL:
POST.CCTL:
00000000 00000000

OC
14
00000000
0000
0000
00000000
00000000
00000000
00
00

12
20

0
0
0

BDB Address: 7FF74150
FLINK:
BLINK:
FLGS:
USERS:
CACHE.VAL:
SIZE:
ADDR:
VBNSEQNO:
WKl:
REL.VBN:
VAL.VBNS:
JNLSEQ:
lOSB:

7FF73648
7FF737A8
03
0000
00
2000
7FF76800
00000000
00000A09
09
OA
00000000
00000A09
7FF77A00

BID:
BLN:
VAL.DRT
0.
0.
8192.

9.
10.
00000000

BLB.PTR:
BUFF.ID:
NUMB:
VBN:
WAIT:
CURBUFADR:
PRE.CCTL:
POST.CCTL:
00000000 00000000

OC
14
00000000
0000
0200
00000001
00000000
7FF77A00
00
00

12
20

0
512
1

In the preceding example, the SET RMS command
that the SHOW PROCESS/RMS command shows t
currently selected for display [indicated by the aster
the ASB (indicated by the NOASB parameter).

System Dump Analyzer
SHOW CLUSTER

SHOW CLUSTER
Displays a view of the VAXcluster or the system communications
services (SCS) cluster. You can display information for all of
the nodes in a VAXcluster, a specific node in a VAXcluster, or
information about the cluster as seen by the SCS.

FORMAT

SHOW CLUSTER

command
parameters

None.

command
qualifiers

/CSID=n
Displays cluster information for a specific VAXcluster member node. The
value that you specify to obtain information for a specific node is that node's
cluster system identification number (CSID).
You can find the CSID for a specific node in a VAXcluster by examining
the first display on your output device after you issue a SHC3w CLUSTER
command.
If you want to obtain CSID information to indicate where a lock is mastered
or held, use the SHOW LOCK command.

/SCS
Displays a view of the cluster as seen by the systems communications services
(SCS).

DESCRIPTION

The SHOW CLUSTER command provides a series of displays to your default
or designated output device.
The first display is a summary of the VAXcluster. This summary includes
the number of votes required for a quorum, the number of votes currently
available, the number of votes allocated to the quorum disk, and a status
summary indicating whether or not a quorum is present. Additionally, the
initial SHOW CLUSTER display lists the cluster system blocks (CSB) currently
in operation; there is one CSB assigned to each node of the VAXcluster. For
each CSB, the first SHOW CLUSTER display shows the node name, the
associated CSB address, the CSID associated with the node, the number of
votes (if any) provided by the node, its state, and its status. (For information
about the state and status of nodes, see the description of the ADD command
in the VAX/VMS Show Cluster Utility Reference Manual.)
The second display for the SHOW CLUSTER command describes the cluster
block (CLUB). The information provided includes a list of flags that have been
activated, a summary of quorum and vote information, and other data that
applies to the VAXcluster from the perspective of the node for which the SDA
is being run.
The next display provides information concerning the cluster failover control
block (CLUFCB) and the cluster quorum disk control block (CLUDCB).

SDA-64

System Dump Analyzer
SHOW CLUSTER

Subsequent displays provide information for the individual cluster system
blocks (that is, for the individual nodes) representing members of the
VAXcluster; each CSB is a separate display. For each CSB, its state and flags
are shown, as well as other information specific to each node. (Information
about the flags for nodes of a VAXcluster is provided in the VAX/VMS Show

Cluster Utility Reference Manual.)
You can obtain information about a specific node of the cluster with the
/CSID=n qualifier, using the CSID value as shown in the first display of the
SHOW CLUSTER command. (You can also obtain this information by using
the SHOW LOCKS command.)
By default, the SHOW CLUSTER command provides a view of the VAXcluster
from the perspective of the connection manager. When you use the /SCS
qualifier, however, you will get a view of the cluster from the perspective of
the port driver or drivers.
The initial display for the SHOW CLUSTER /SCS command provides an
overview of processes that are listening for incoming SCS connect requests.
For each of these processes, this first display shows its entry address,
connection ID, process name, and explanatory text, if any.
The second display with the /SCS qualifier is a summary of SCS systems.
These systems can include cluster members (as shown in the SHOW
CLUSTER command), HSCs, UDAs, and other such devices. For each of
these SCS systems, the system block (SB) address, node name, system type,
system ID, and the number of connection paths are shown.
Subsequent displays provide detailed information for each of the system
blocks and the associated path blocks. The system block displays include the
maximum message and datagram sizes, local hardware and software data,
and SCS poller information. Path block displays include information that
describes the connection, including remote functions and other path-related
data.

EXAMPLES
Q

SDA>

SHOW CLUSTER

- VAXcluster Summary Quorum

Votes

Quorum Disk Votes

Status Summary
quorum

--- CSB list —
Address

Node

CSID

803686F0
80368550
80367B90

SOLLY
GUS
DORIS

000100C8
000100C9
000100C5

Votes

State

1
1
1

open
open
open

Status

member,qf.active
member,qf.active
member,ql.active

SDA-65

$255$DUA2
0000000008A0
3-DEC-1985
00:01:44
Index of next CSID
00D2
Quorum Disk Cntrl Block 80334E00
Timer Elntry Address
00000000
CSP Queue
empty

Quorum Disk
Found Node SYSID
Founding Time

Last time staunp

26-MAR-1986
18:52:32
Largest trans. id
00000466
Resource Alloc. retry
0
Figure of Merit
00000000
Member State Seq. Num
0190
Foreign Cluster
00000000

- Cluster Failover Control Block (CLUFCB) 801C407C Flags: 00000000
Failover Step Index
Failover Instaince ID

00000028
00000466

CSB of Synchr. System

803686F0

- Cluster Quorum Disk Control Block (CLUDCB) 80334E00 State: 0(X)1 qs.not.ready
Flags: 0000
Iteration Counter
Activity Counter
Quorum file LBN

0
0
00000000

UCB address
TQE address
IRP address

00000000
80419F40
803665A0

- SOLLY Cluster System Block (CSB) 803686F0 State: 01 open
Flags: 02020302 member,cluster,qf.active,selected,status.rcvd
Quorum/Votes
2/1
Quor. Disk Vote
1
CSID
000100C8
Eco/Version
0/12
Reconn, time 00000059
Ref. count
2
Ref. time
18--DEC-1985
08:53:58

Next seq. number
0247
Last seq num rcvd
0314
Last ack. seq num
0247
Unacked messages
1
Ack limit
4
Incarnation 18-DEC -1985
08: 52:20
Lock mgr dir wgt
1

Send queue
Resend queue
Block xfer Q.
CDT address
PDT address
TQE address
SB address
Current CDRP

00000000
00000000
empty
801C28F0
801CEA20
00000000
8041B6E0
00000000

The preceding example shows the screen displays for the SHOW
command. (Displays for nodes GUS and DORIS, similar to that
SOLLY, are also included in the SHOW CLUSTER output but h
omitted from the preceding example.)
2

SDA> SHOW CLUSTER /CSID=000100C8

Next seq. number
0247
Last seq num rcvd
0314
Last ack. seq num
0247
Unacked messages
1
Ack limit
4
Incarnation 18-DEC -1985
08: 52:20
Lock mgr dir wgt
1

Send queue
Resend queue
Block xfer Q.
CDT address
PDT address
TQE address
SB address
Current CDRP

00000000
00000000
empty
801C28F0
801CEA20
00000000
8041B6E0
00000000

The preceding example shows the use of the /CSID qualifier to
information about a specific node (in this instance, node SOLLY
information displayed is identical to that shown for the specifie
the SHOW CLUSTER command.

SDA-66

80419D60
80419E20

08EEOOOO
08EE0001

SCSSDIRECTORY
VMS$VAXcluster

- SCS Systems Summary SB Address

Node

Type

System ID

Paths

8041A120
8041AA20
8041AB40
8041B6E0
8041D420

PINTO
DORIS
GUS
SOLLY
DODGER

HSC
VMS
VMS
VMS
HSC

OOOOOOOOFIOE
0000000008A9
0000000008A1
0000000008A0
OOOOOOOOFOOF

1
1
1
1
1

—

PINTO System Block (SB) 8041A120

System ID
OOOOOOOOFIOE
Max message size
66
Max datagr2un size
62
Local hardware type
HS50
Local heirdware vers. 022702220222
022202220222

—

Local software type
Local software vers.
Local software incarn.
SCS poller timeout
SCS poller enable mask

HSC
X25C
8366FE00
008DA59A
OOOF
01

--- Path Block (PB) 8041C400 --Status:

0000

Remote sta. addr.
OOOOOOOOOOOE
Remote state
OOOOOOOOOOOE
Remote hardwaire rev.
00000226
Remote func. mask
4F710200
Reseting port
OE
Handshake retry cnt.
1
empty
Msg. buf. wait queue

Remote port type
Number of data paths
Cables state
Local state
Port dev. name
SCS MSGBUF address
PDT address

HSC
2
A-OK B-OK
OPEN
PABO
80390270
801CEA20

ssss:SSSSSSS3SSSSSSS ssssssssssssssssssssssssass

DORIS System Block (SB) 8041AA20 --System ID
0000000008A9
Meix message size
112
Maix datagraon size
576
Local hardware type
V780
Local hardware vers. 010E0138207A
000030030E10

Local software type
Local software vers.
Local software incarn.
SCS poller timeout
SCS poller enable mask

VMS
V4.1
A9D31760
008DA59B
OOOC
00

- Path Block (PB) 80437E80 --Status:

0000

Remote sta. addr.
000000000002
Remote state
ENAB
Remote hardware rev.
00040003
Remote func. mask
FFFFFFOO
Reseting port
02
Handshake retry cnt.
1
Msg. buf. wait queue
empty

Remote port type
Number of data paths
Cables state
Local state
Port dev. name
SCS MSGBUF address
PDT address

CI780
2
A-OK B-OK
OPEN
PABO
8036F0B0
801CEA20

The preceding example shows a subset of a typical
CLUSTER /SCS command. In this system, there ar
(DORIS, GUS, and SOLLY), and there are two HSC
After the summary information in the first two scre
information for each system block and its associated

System Dump Analyzer
SHOW CONNECTIONS

SHOW CONNECTIONS
Displays all active connections between systems communication
services (SCS) processes. This information is retrieved from
connection descriptor tables (CDTs). You can also display
information for a specific CDT to obtain information about an
individual connection.

FORMAT

SHOW CONNECTIONS

command
parameters
command
qualifiers

None.

/ADDRESS=n
Displays information for a specific CDT. The addresses for individual CDTs
are listed in the CDT summary page, which is the first display provided for
the SHOW CONNECTIONS command.

DESCRIPTION The SHOW CONNECTIONS command provides a series of displays to your
default or designated output device.

The first display is a summary of the connection descriptor tables (CDTs).
For each CDT, the display lists its address, the local process with which the
CDT is associated, the connection ID, its current state, and the remote node to
which it is currently connected (if any). This display also shows the number
of CDTs that are currently free and available to the system.
CDT addresses, in addition to being available from the summary page shown
by the SHOW CONNECTIONS command, are also stored in many individual
data structures related to SCS connections. These data structures include
CDRPs and UCBs for class drivers that use SCS and CSBs for the connection
manager.
Next, there is a display of detailed information for each CDT that is listed
on the first page summary. This information includes the current state, the
associated local process, the associated remote node and process (if any), and
detailed connection information. (See Example 1 for a list of the information
available.)
You can obtain information for the individual connection between two SCS
processes by using the /ADDRESS=n qualifier, obtaining the appropriate
address either from the CDT summary table in the first display of the SHOW
CONNECTIONS command or from an appropriate data structure.

SDA-68

CDT Address

Local Process

801C2670
801C2710
801C27B0
801C2860
801C28F0
801C2990

SCSIDIRECTORY
VMS$VAXcluster
VMS$VAXcluster
VMS$DISK.CL_DRVR
VMS$VAXcluster
VMS$VAXcluster

Number of free CDT's:

Connection ID

State

Remote Node

08EE0000
08EE0001
08FF0002
08FD0003
08EF0004
08F00005

listen
listen
open
open
open
open

DORIS
PINTO
SOLLY
GUS

- Connection Descriptor Table (CDT) 801C2670 State:
0001 listen
Blocked State:
0000

Local Process:

Local Con. ID
08EE0000
Remote Con. ID 78A30017
Receive Credit
0
Send Credit
1
Min. Rec. Credit
0
Pend Rec. Credit
0
Initial Rec. Credit
0
Rem. Sta.
OOOOOOOOOOOC
Rej/Disconn Reason
0
Queued for BDT
0
Queued Send Credit
0

Datagreons sent
Datagrams rcvd
Datagreun discard
Messages Sent
Messages Rcvd.
Send Data Init.
Req Data Init.
Bytes Sent
Bytes rcvd
Total bytes map

SCS$DIRECTORY

0
0
0
0
0
0
0
0
0
0

Message queue
Send Credit Q.
PB address
PDT address
Elrror Notify
Receive Buffer
Connect Data
Aux. Structure

empty
empty
80438300
801CEA20
8022B816
00000000
00000000
00000000

The preceding example shows the first display, the
the first page of the detailed displays for each CDT
of each CDT is provided when you issue the SHO
command.
SDA>

SHOW CONNECTIONS /ADDRESS=801C27B0
- Connection Descriptor Table (CDT) 801C27B0

State:
0002 open
Blocked State:
0000

Local Process:
Remote Node::Process:

VMSiVAXcluster
DORIS::VMS$VAXcluster

Local Con. ID
08FF0002
Remote Con. ID 33440003
Receive Credit
4
Send Credit
5
Min. Rec. Credit
0
Pend Rec. Credit
1
Initial Rec. Credit
5
Rem. Sta.
000000000002
Rej/Disconn Reason
0
Queued for BDT
0
Queued Send Credit
0

Datagrams sent
0
Datagrams rcvd
0
Datagram! discard
0
Messages Sent
267
Messages Rcvd.
289
Send Data Init.
0
Req Data Init.
0
Bytes Sent
0
Bytes rcvd
0
Total bytes map
0

Message queue
Send Credit Q.
PB address
PDT address
Error Notify
Receive Buffer
Connect Data
Aux. Structure

empty
empty
80437E80
801CEA20
80227960
8039AF80
80367C0C
80367B90

The preceding example shows the use of the /ADD
information about a specific connection. The addres
the table is obtained either from the CDT summary
data structure.

System Dump Analyzer
SHOW CRASH

SHOW CRASH
Displays information concerning the operating system and the
currently executing process. The display shows the following:
• Operating system and process information
• General and special register contents
• Processor and hardware maintenance register contents

FORMAT

SHOW CRASH

None.
command
parameters
None.
command
qualifiers
DESCRIPTION The SHOW CRASH command displays information in three sections. The
contents of each display is described here:
Operating System and Process Information
The first section of the SHOW CRASH display lists the following:
•

Date and time of the crash

•

Name and version number of the operating system

•

Reason for the bugcheck

•

Name of the currently executing process

•

Specification of the file that contains the image executing in the process
context (left blank if no image is executing)

•

Interrupt priority level (in decimal) of the processor

Contents of General and Special Registers
The second section of the SHOW CRASH display lists the contents of the
general registers and the special registers as follows:

SDA-70

•

RO through Rll

•

Argument pointer (AP)

•

Frame pointer (FP)

•

Stack pointer (SP)

•

Program counter (PC)

•

Processor status longword (PSL)

System Dump Analyzer
SHOW CRASH

Contents of Process and Hardware-Maintenance Registers
The third section of the SHOW CRASH display lists the contents of three sets
of registers. The first set includes registers that store the vital statistics of the
currently executing process, as well as registers that contain information used
by the operating system. The second set of registers are pointers to the five
stacks, those being the interrupt stack and the stack for each processor access
mode. The third set of registers are used in hardware maintenance.
Each type of VAX processor supports a different set of hardware (processor)
registers, but all have the same process and system registers, and the same
stack pointers. In any case, the processor type is displayed.
The process and system registers are as follows:
•

Program region base register (POBR)

•

Program region length register (POLR)

•

Control region base register (PIBR)

•

Control region length register (PILR)

•

System region base register (SBR)

•

System region length register (SLR)

•

Process control block base register (PCBB)

•

System control block base register (SCBB)

•

Asynchronous system trap level (ASTLVL)

•

Software interrupt summary register (SISR)

•

Internal clock control/status register (ICCS)

•

System identification register (SID)

The stack pointers are as follows:
•

Interrupt stack pointer (ISP)

•

Kernel-mode stack pointer (KSP)

•

Executive-mode stack pointer (ESP)

•

Supervisor-mode stack pointer (SSP)

•

User-mode stack pointer (USP)

EXAMPLE
SDA> SHOW CRASH
System crash information
VAX/VMS 4.4 -- System Dump Analysis

06-JAN-1986 16:22:29.13

Page 1

VAX/VMS 4.4 -- System Dump Analysis
System crash information

06-JAN-1986 16:22:29.13

Page 2

Time of system crash: 06-JAN-1986 16:21:63.38
Version of system: VAX/VMS VERSION X4.4
VAXcluster node name: REDDOG

SDA-71

General registers:
RO - 00000000
R4 * 00000000
R8 » 00000000
AP - 00000000
PSL * 00000000

R1
R5
R9
FP

* 00000000
= 00000000
= 00000000
= 00000000

R2 * 00000000
R6 = 00000000
RIO - 00000000
SP * 00000000

Processor registers:

VAX 8600

POBR
POLR
PIBR
PILR

= 00000000
= 00000000
= 00000000
* 00000000

SBR
SLR
PCBB
SCBB

ICR
TODR
ACCS

= 00000000
* 00000000
» 00000000

SBISTS * 00000000
SILOCMP* 00000000
MAIN! * 00000000

ISP
KSP
ESP
SSP
USP

* 00000000
= 00000000
= 00000000
* 00000000
* 00000000

VAX/VMS 4.4 -- System Dump Analysis
System crash information

00000000
00000000
* 00000000
00000000

ASTLVL
SISR
ICCS
SID

R3
R7
Rll
PC

= 00000000
* 00000000
* 00000000
* 00000000

* 00000000
* 00000000
* 00000000
= 0404F00B

SBIERR = 00000000
TM0ADDRS*OOOOOOOO

06-JAN-1986 16:22:29.13

Page 3

SBI silo contents:
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
00000000

The SHOW CRASH command displays the preceding information f
running system.

SDA-72

System Dump Analyzer
SHOW DEVICE

SHOW DEVICE
Displays a list of all data structures associated with a device.

FORMAT
command
parameter

command
qualifier

SHOW DEVICE [device-name]
device-name
The name of the device for which you want information. If you do not
include this parameter, this command displays information on all devices in
the system.

/ADDRESS=n
The address of the UCB of the device of interest. Using this qualifier with the
SHOW DEVICE command is equivalent to specifying the name of the device
with the command.

DESCRIPTION The SHOW DEVICE command displays three data structures listed next:
•

The device data block

•

The controller data structure

•

The unit data structures

If you provide the name of a device as a parameter to this command, the
information is displayed for that device. In a cluster environment, the
information is displayed for each device in the cluster with that name. If
you provide no parameter, the information is displayed for every device
configured in the system.
If you omit part of a device name, all devices that have a part of their device
name matching that which you specified are displayed by the SHOW DEVICE
command.
For a detailed explanation of I/O data structures displayed by SDA, consult
the manual entitled Writing a Device Driver for VAX/VMS.

EXAMPLES
□

SDA> SHOW DEVICE VTAIOO
I/O data structures
VTAIOO =*> LTA83

VT200_Series

UCB address:

802292B0

Device status:
00010010 online.deleteucb
Characteristics: 0C040007 rec,ccl,trm,avl,idv,odv
00000200 nnml

SDA-73

I/O request queue is empty *♦*
SDA>

SDA> SHOW DEVICE DUSO

VAX/VMS 4.4 -- 1System Dump Analysis

06-JAN -1986 13: 38:43.21

ACTI$DUS0

RA81

Page 1

UCB address:

80000FF8

Device status:
00001810 online,valid,unload
Characteristics : 1C4D4008 dir,fod,shr,avl,mnt,elg,idv,odv,rnd
00000221 clu.mscp.nnm
Owner UIC [000001,000001]
PID
00000000
Alloc, lock ID
00030002
254
Alloc. class
Class/Type
01/16
512
Def. buf. size
DEVDEPEND
04E00E33
DEVDEPND2
00000000
FIPL/DIPL
08/08

Operation count
Error count
Reference count
Online count
Retry cnt/max
BOFF
Byte count
SVAPTE
DEVSTS
RWAITCNT

96308
0
110
0
8/8
0000
0200
81B1BFA0
0004
0000

ORB address
DDB address
DDT address
VCB address
CRB address
PDT address
CDDB address
I/O wait queue

80000FA0
80000F6C
801D5548
80196C30
803943E0
802C7020
80178AD0
empty

- Primary Class Driver Data Block (CDDB) 80178AD0 --1040 alcls.set.bshadow
80D6 cf_shadw,cf_mlths,cf _this,cf..misc,cf_attn,cf_ replc

Status:
Controller Flags:

Allocation class
264
System ID
0000FFF2
0000
0000FFF2
Contrl. ID
01010000
E7BA0020
Response ID
MSCP Cmd status 00001879

CDRP Queue
Restart Queue
DAP Count
Contr. timeout
Reinit Count
Wait UCB Count

DDB address
CRB address
CDDB link
PDT address
Original UCB
UCB chain

80337830
empty
3
75
4
0

80000F6C
803943E0
8019C020
802C7020
00000000
8017B0B0

I/O request queue
WCB

EFN

AST

lOSB

STATUS

OOOC
80334EC0
readpblk func,pagio,virtual

80396F40

80CA9888

0040FE10

0016

OOOC
8032A4F0 0006006E E
readpblk func.pagio.virtual

80398E80

80B37068

0040FE70

0016

OOOC
80323740 00060047 E
readpblk func,pagio,virtual

803A3920

80A69410

0040FE60

0016

STATE CDRP/IRP

PID

FUNC

--- Volume Control Block (VCB) 80196C30
Volume: CERIUM
Lock naune: CERIUM
Status:
AO extfid.system
Status2: 15 writethru,mountver.nohighwater
Shadow status: 21 shadmast.mvbegun
Mount count
Tramsactions
Free blocks
Window size
Vol. lock ID
Block, lock ID
Shadow lock ID

SDA-74

1
93
199020
7
00010004
02F20206
00010006

Rel. volume
Max. files
Rsvd. files
Cluster size
Def. extend sz.
Record size

0
222768
9
1
5
0

AQB address
RVT address
FCB queue
Cache blk.
Shadow mem. FL
Shadow mem. BL

803A8480
80000FF8
803081C0
80195D20
803A88A0
803A89C0

$254$DUA201

ACTI

ANTIM

Copy in progress

- ACP Queue Block (AQB) 803A8480 --■ACP requests are serviced by the Extended QIO Processor (XQP)
Status:

14 defsys.xqioproc

Mount count

ACP type
ACP class

fllv2
0

Request queue

empty

UCB address:

8017C3F0

ACP request queue is empty ***
ACTI$DUA200 (ANTIM$DUA200)

RA81

Device status:
00000010 online
Characteristics: 1C4D4108 dir,ret,fod,shr,avl ,mnt,elg,idv,odv,rnd
00000271 clu,2p,msep,ssm,nnm
Owner UIC [000000,000000]
PID
00000000
Alloc, lock ID
OIAIOIFI
Alloc, class
254
Class/Type
01/15
Def. buf. size
512
DEVDEPEND
04E00E33
DEVDEPND2
00000000
FIPL/DIPL
08/08

Operation count
Error count
Reference count
Online count
BOFF
Byte count
SVAPTE
DEVSTS
RWAITCNT

6
1
1
0
0000
0000
00000000
0004
0000

ORB address
DDB address
DDT address
VCB address
CRB address
PDT address
CDDB address
2P_CDDB addr.
2P_DDB address
I/O wait queue

8017C4F6
80397620
801D5548
803A88A0
803943E0
802C7020
80178AD0
8019DD80
80397440
empty

Virtual unit UCB
Virtual unit VCB
Shadow member FL
Shadow member BL

80000FF8
80195C30
803A89C0
80195CC8

06-JAN-1986 13:38:43.21

Page 3

UCB address:

8017C650

♦♦♦ I/O request queue is empty ***
-•-- Volume Control Block (VCB) 803A88A0 Volume: CERIUM
(Member of shadow set $254$DUS0)
Status: 00
Copy sequence number: 0000 Copy type: 0 nocpy
Transactions
1
Relative volume
0
AQB address
803A8480
RVT address
80000FF8

UCB address
Work 2u:ea

8017C3F0
00000000
00000000

VAX/VMS 4.4 -- System Dump Analysis
I/O data structures
ACTI$DUA201 (ANTIM$DUA201)

RA81

Device status:
00000010 online
Chsiracteristics: 1C4D4108 dir,ret,fod,shr,avl ,mnt,elg,idv,odv,rnd
00000271 clu,2p,msep,ssm,nnm
Owner UIC [000000,000000]
PID
00000000
Alloc, lock ID
00010008
Alloc, class
254
Class/Type
01/15
Def. buf. size
512
DEVDEPEND
04E00E33
DEVDEPND2
00000000
FIPL/DIPL
08/08

Operation count
Error count
Reference count
Online count
BOFF
Byte count
SVAPTE
DEVSTS
RWAITCNT

9
0
1
0
0000
0200
81B19AAC
0004
0000

ORB address
DDB address
DDT address
VCB address
CRB address
PDT address
CDDB address
2P_CDDB addr.
2P_DDB address
I/O wait queue

8017C656
80397620
801D5548
803A89C0
803943E0
802C7020
80178AD0
8019DD80
80397440
empty

*** I/O request queue is empty ♦**
--- Volume Control Block (VCB) 803A89C0 --Volume: CERIUM
(Member of shadow set $254$DUS0)
Status: 08 rebldng
Copy sequence number: OOOA Copy type: 1 copy
Transactions
1
Relative volume
0
AQB address
803A8480
RVT address
80000FF8

UCB address
Work area

8017C550
00000000
00000000

Virtual unit UCB
Virtual unit VCB
Shadow member FL
Shadow member BL

80000FF8
80196C30
80195CC8
803A88A0

DDB list
Address

Controller

ACP

Driver

DPT

DPT size

808CC6C0
808CC7A0
80900640
80903820
80904AE0

ANTIIDJA
ANTI$DJS
CERIUIDJA
NOBIIDJA
SELEIDJA

FllXQP
FllXQP
FllXQP
FllXQP
FllXQP

DUDRIVER
DUDRIVER
DUDRIVER
DUDRIVER
DUDRIVER

8066F000
8066F000
8066F000
8055F000
8066F000

60F8
60F8
60F8
60F8
60F8

I/O data structures
Controller: ANTI$DJA
--- ANTI System Block (SB) 808C9080 --00000000FFF2
System ID
Max message size
66
62
Max datagram size
Local hardware type
HS50
Local hairdware vers. 02270222031A
022702270227

Local software type
Local software vers.
Local software incarn.
SCS poller timeout
SCS poller enable mask

HSC
X6J6
CE9DD540
008E6F20
0007
01

I/O data structures
--- Path Block (PB) 808EDCE0 --Status:

0008

OOOOOOOOOOOB
Remote sta. addr.
OOOOOOOOOOOB
Remote state
Remote hardware rev.
00000226
Remote func. mask
4F710200
OB
Reseting port
Handshaike retry cnt.
1
Msg. buf. wait queue
empty

Remote port type
Number of data paths
Cables state
Local state
Port dev. name
SCS MSGBUF address
PDT address

HSC
2
A-OK B-OK
OPEN
PAAO
80739670
806FA820

Device Data Block (DDB) 808CC5C0 Driver name
ACP ident
ACP class

DUDRIVER
Fll
PACK

Alloc. class
SB address
UCB address

254
808C9080
804D13E0

DDT address
CONLINK addr.

DDB list
Address

Controller

ACP

Driver

DPT

808CC5C0
80900640
80903820
80904AE0

ANTI$DJA
CERIU$DJA
N0BI$DJA
SELE$DJA

FllXQP
FllXQP
FllXQP
FllXQP

DUDRIVER
DUDRIVER
DUDRIVER
DUDRIVER

8065F000
8065F000
8056F000
8066F000

SDA-76

DPT size
60F8
60F8
60F8
60F8

8066F088
808CC7A0

Max datagrsun size
62
Local hardw2Lre type
HS50
Local hardware vers. 02270222031A
022702270227

Local softw£Lre incarn.
SCS poller timeout
SCS poller enable mask

CE9DD540
008E6F20
0000
01

The preceding example shows the display produce
DEVICE to match all devices that use DJ as part of

command
parameters
command
qualifiers

None.

DESCRIPTION

The display produced by the SHOW HEADER command c
taken from the header of the dump file.

None.

EXAMPLE
SDA> SHOW HEADER
Dump file header
00000000 00000000 00000000 00000000 00000000 00000000 00000001 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

The preceding example shows the display produced by th
command.

SDA-78

System Dump Analyzer
SHOW LOCK

SHOW LOCK
Displays a list of all locks in the system.

FORMAT

SHOW LOCK lockid

command
parameters

The number of a specific lock.

command
qualifier

lockid

/ALL
Lists all locks that exist in the system.

DESCRIPTION The display produced by the SHOW LOCK command contains information

on each lock in the system. The display is formatted in the same way as the
display produced by the command SHOW RESOURCE/LOCKID.

EXAMPLE
SDA> SHOW LOCK
Lock database
Lock id:
00010001
PID:
00000000
Flags:
NOQUEUE SYNCSTS SYSTEM
Par. id:
00000000
Granted at
EX
CVTSYS
Sublocks:
4
LKB:
801F4F00
Resource:
6F536963 24536963
SYS$SYS_ Status:
NOQUOTA
Length
16
00000000 00A94449
ID.
Exec. mode
00000000 00000000
.
System
00000000 00000000
.
00020002
PID:
00000000
Flags:
VALBLK CONVERT SYNCSTS
Lock id:
Granted at
CR
NOQUOTA CVTSYS
00000000
Par. id:
Sublocks
0
80201680
LKB:
SYS$_DEL Status:
NOQUOTA
Resource
4C46445F 24636963
30414244 24494850
PHIIDBAO
Length
17
00000000 0000003A
Kernel mode
System
00000000 00000000

The preceding example shows the display produced by the command SHOW
LOCK.

SDA-79

System Dump Analyzer
SHOW PAGE-TABLE

SHOW PAGE-TABLE
Displays a list of system page table entries that map virtual pages to
physical pages. You can display a range of page table entries or the
entire system page table.
The SHOW PAGE—TABLE command displays information in 132
columns, rather than 80 columns, and so is best suited for use at
printing terminals, at video terminals that can display 132 columns,
or as input for a file that can be printed later on a line printer.

FORMAT
command
parameter

command
qualifiers

SHOW PAGE_TABLE [/qualifierf,...]] [range]
range
The range of virtual addresses for which SDA is to display page table entries.
You can specify a range as a beginning address and an ending address,
separated by a colon (:); or you can specify the range as an address and the
number of bytes following that address, separated by a semicolon (;).

/GLOBAL
Lists the global page table.

/SYSTEM
Lists the system page table.

/ALL
Lists both the global and system page tables. This is the default qualifier.

DESCRIPTION The SHOW PAGE—TABLE command displays the contents of the system

page table and the global page table. You can display a range of page table
entries or the entire system page table.
This command displays information in 15 columns that form two groups. The
left group contains information on virtual pages. The right group contains
information on physical pages.
The left group contains information obtained from the system page table.
Each line of this display lists characteristics of a virtual page as well as
information needed for address translation. The headings of the columns
listed in the display produced by the SHOW PAGE—TABLE command are
explained in the following text.

SDA-80

System Dump Analyzer
SHOW PAGE-TABLE

Value

Meaning

ADDRESS

The system virtual address that marks the base of a virtual page.

SVAPTE

The system virtual address of the page table entry that maps this
virtual page.

PTE

The contents of the page table entry, a longword that describes a
system virtual page.

Type

Type of virtual page. There are eight types.
Type

Meaning

VALID

A valid page (in main memory).

TRANS

A transitional page (between main memory and page
lists).

DZERO

A demand-allocated, zero-filled page.

PGFIL

A page within a paging file.

STX

A section table's index page.

GPTX

An Index page for a global page table.

lOPAG

A page In the I/O address space.

NXMEM

A page not represented in physical memory. The page
frame number (PFN) of this page is not mapped by any
of the system's memory controllers. This Indicates an
error condition.

PROT

Protection, a code, derived from bits in the PTE, that designates
the type of access (read and/or write) granted to processor access
modes (kernel, executive, supervisor, or user).

Bits

Letters that represent the setting of a bit or a combination of bits
in the PTE. These bits indicate attributes of a page. The codes are
listed following.
Code

Meaning

The page has been modified.

The page is locked into a working set.

The owner can access the page in kernel mode.

The owner can access the page In executive mode.

The owner can access the page in supervisor mode.

The owner can access the page in user mode.

If the virtual page has been mapped to a physical page, the right-hand section
of the display includes information from the page frame number (PFN)
database. Otherwise, the section is left blank. SDA organizes the 18 bytes of
PFN data into 9 categories:

SDA-81

System Dump Analyzer
SHOW PAGE_TABLE

Category

Meaning

PAGTYP

Type of physical page, one of six types.

LOG

Page Type

Meaning

PROCESS

The page is part of process space.

SYSTEM

The page is part of system space.

GLOBAL

The page Is part of a global section.

PPGTBL

The page is part of a process's page table.

GPGTBL

The page Is part of a global-page table.

GBLWRT

The page is part of a global, writeable section.

The location of the page within the system, one of eight types.
Location

Meaning

ACTIVE

The page is in a working set.

MDFYLST

The page is In the modified-page list.

FREELST

The page Is In the free-page list.

BADLST

The page Is In the bad-page list.

RELPEND

Release of the page is pending.

RDERROR

The page has had an error during an attempted read
operation.

PAGEOUT

The page is being written Into a paging file.

PAGEIN

The page is being brought into memory from a paging
file.

STATE

The byte that describes the state of the physical page.

TYPE

The byte that describes the type of virtual page. The types in this
column are the hexadecimal codes that stand for the page types
that appear In column PAGTYP of this display, described previously.

REFCOUNT

A count of the processes that are referencing this PFN. If the value
of REFCOUNT is nonzero, the page is used in at least one working
set. If the value Is zero, the page is not used in any working set.

BAK

The address of the backing store; location on a disk device to
which pages can be written.

SVAPTE

The virtual address associated with this page frame. The two
SVAPTEs indicate a valid link between physical and virtual address
space.

FUNK

The forward link within PFN database that points to the next
virtual page; this longword also acts as the count of the number of
processes that are sharing this global section.

BLINK

The backward link within PFN database; also acts as an index Into
the working set list.

SDA indicates pages are inaccessible by displaying the following message,
where n represents the number of inaccessible pages.
(-n null PAGES)

SDA-82

80000C00
80000EOO
80001000
80001200
80001400
80001600
80001800

80B91C18
80B91C1C
80B91C20
80B91C24
80B91C28
80B91C2C
80B91C30

EC001AE3
F4001AE4
F4001AE5
F4001AE6
F4001AE7
F4001AE8
F0001AE9

VALID
VALID
VALID
VALID
VALID
VALID
VALID

UREW M
URKW M
URKW M
URKW M
URKW M
URKW M
URKW

K
K
K
K
K
K
K

The preceding example shows the output
TABLE command.

System Dump Analyzer
SHOW PFN_DATA

SHOW PFN_DATA
Displays information that is contained in the page lists and in the
PFN database. This information is used in translating physical page
addresses to virtual page addresses.

FORMAT

SHOWPFN_DATA [number]

command

number

paranriBtBr

The number of the physical page for which you want to display information.

command
qualifiers

/ALL
Displays all of the previous information. This is the default for the command.

/BAD
Displays the bad-page list.

/FREE
Displays the free-page list.

/MODIFIED
Displays the modified-page list.

/SYSTEM
Displays the PFN database. The information is ordered by page frame
number, starting at PFN zero.

DESCRIPTION The SHOW PFN—DATA command causes SDA to display information
regarding the specified PFN. The display consists of the information listed in
the example following.
SDA> SHOW PFN.DATA 1000
PFN
PTE ADDRESS
BAK
1000

8034AA60

0040FFB8

REFCNT FLINK BLINK
1

0000 0236

TYPE

STATE

00 PROCESS

07 ACTIVE

The items of information are the following:

SDA-84

System Dump Analyzer
SHOW PFN_DATA

Item

Contents

PFN

The page-frame number, the number of this physical page

PTE ADDRESS

The system virtual address of the page table entry that
describes the virtual paged mapped into this physical page

BAK

The place to find information on this page when all links to this
PTE are broken, either an index into a process section table or
the number of a virtual block in the paging file

REFCNT

The number of references being made to this page

FLINK

The address of the next page In the list In which this virtual
page currently resides

BLINK

The address of the previous page in the list In which this virtual
page currently resides

TYPE

The type of virtual page, one of the following:

STATE

Code

Meaning

Process page

System page

Global, read-only page

Global, read/write page

Process page-table page

Global page-table page

The state of the virtual page, one of the following:
Code

Meaning

The page is on the free list.

The page is on the modified list.

The page is on the bad-page list.

Release of the page to the free-page or modified list is
pending.

An error occurred as the page was being read from the
disk.

The modified-page writer is currently writing the page
to the disk.

The page-fault handler Is currently reading the page
from the disk.

The page is active and valid.

EXAMPLE
SDA> SHOW PFN.DATA
Free page list
Count:
Low limit;
High limit:

225
67
1073741824

PFN

PTE ADDRESS

BAK

1329

8047AF3C

03002A83

REFCNT FLINK BLINK
0

1963 0000

TYPE

STATE

00 PROCESS

00 FREELST

SDA-85

1485

8047AC80

030010B3

1707 1529

00 PROCESS

00 FREELST

The SHOW PFN_DATA command displays the information shown
previously for the free-page list, the modified-page list, and the badlist, and then all of the PFN database, including the first three lists.

SDA-86

System Dump Analyzer
SHOW POOL

SHOW POOL
Displays the contents of the look-aside (SRP, IRP, and LRP) pools,
the nonpaged dynamic storage pool, and the paged dynamic storage
pool. You can display part or all of each pool.

FORMAT
command
parameter

command
qualifiers

SHOW POOL

[range]

range
The range of virtual addresses that you want to display. You can specify
a range as two addresses separated by a colon (:), or as an address and a
length, in bytes, separated by a semicolon (;).

/ALL
Displays the entire contents of memory. This is the default.

/FREE
Displays the look-aside, paged, and nonpaged pools and shows the blocks
that are currently available to the system.

/HEADER
Displays only the first 16 longwords of each block within the pool.

/IRP
Displays the pool of I/O request packets. Displays all blocks currently
allocated (in use) within this pool.

/LRP
Displays the pool of long I/O request packets. Formats all blocks currently
allocated (in use) within this pool.

/NONPAGED
Displays the nonpaged dynamic storage pool currently in use by the system.

/PAGED
Displays the paged dynamic storage pool currently in use by the system.

/SRP
Displays the pool of short I/O request packets. Formats all blocks currently
allocated (in use) within this pool.

/SUMMARY
Displays a summary of the pools or portions of pool specified by the qualifiers
shown previously. This qualifier shows the different types of blocks present,
the total number of each, the decimal number of bytes in each block, and the
number of bytes used in each pool.

SDA-87

System Dump Analyzer
SHOW POOL

/TYPE=block-type
Displays the blocks within pool that are of the specified type.

DESCRIPTION The information contained in each of the three pools is shown in the same
format. The contents of the display, from left to right, are listed as follows:
Column

Contents

Block type

The type of information contained in the block. SDA
tries to interpret the block type; If it is unable to do so,
SDA displays the block type as UNKNOWN.

Starting address

The virtual address that marks the start of the block.

Block size

The number (decimal) of bytes of memory allocated to
the block. The block size is fixed in the SRP, IRP, and
LRP pools, and is variable in the paged and nonpaged
pools.

Contents

The contents of the block, arranged in four columns
of longwords. The contents of the longwords are
represented in hexadecimal. On each line of the display,
the longwords are arranged from right to left, in the
order of their addresses.

Contents

The contents of the block, arranged in one column of
ASCII characters. The column is 16 characters wide.
Each character represents the ASCII value of the bytes
within the longwords on that line. If the ASCII value of
a byte is not a printing character, SDA prints a period
character (.) instead. The characters are arranged from
left to right, in order of their addresses.

EXAMPLE
SDA> SHOW POOL
IRP
8013B240

160
07010000 000A0064 00000000 000A0064 T.T.

The preceding example shows two lines from a display produced by the
SHOW POOL command. This block is an IRP; its starting address is
8013B240; and its length is 160 bytes. Note that the first byte of the longword
at 8013B240, the rightmost byte in the hexadecimal display, contains 54, the
ASCII value of the character uppercase T. This value is represented as the
leftmost character in the ASCII portion of the display.
Similarly, the byte at location 8013B48, the ninth byte from the right in the
hexadecimal display, also contains 54. It is represented by the T in the ninth
place from the left in the ASCII display.

SDA-88

System Dump Analyzer
SHOW PORTS

SHOW PORTS
Displays those portions of the port descriptor table (PDT) that are
port independent. Port-independent items in the PDT are used by all
system communications services (SCS) port drivers.

FORMAT

SHOW PORTS

command
parameters
command
qualifiers

None.

/ADDRESS=n
Displays a specific port descriptor table, as specified by the address. The
PDT summary page, which lists the addresses for individual PDTs, is the first
display shown for the SHOW PORTS command.

DESCRIPTION The SHOW PORTS command provides information for those Cl ports with
full SCS connections. Therefore, information about UDA ports and similar
controllers is not included in the output of this command.

The initial display is a PDT summary page, listing the PDT address, port
type, device type, and driver name for each PDT. Subsequent displays
provide detailed information for each PDT listed on the summary page.
Information for a particular PDT can also be obtained by using the
/ADDRESS qualifier to the SHOW PORTS command.

EXAMPLE
SDA> SHOW PORTS
-PDT Siimmary PagePDT Address

Type

Device

Driver Name

801CEA20

PABO

PADRIVER

-Port Descriptor Table (PDT) 801CE1A20Type: 01 pa
Characteristics: 0000
Msg Header Size
32
Max XIer Bent
FFFFFFFF
72
DG Header Size
Poller Sweep
25
Fork Block W.Q.
empty
UCB Address
80335320
ADP Address
00000000
80232277
Accept
802324F8
Alloc_Dg_Buf
Alloc_Msg_Buf
80232383
8023243C
Dealloc_Msg_Bul
Dealloc_Msg_Bul_Reg 8023244F

Connect
Dealloc_Dg_Buf
Disconnect
Unmap
Map
Map_Bypass
Map_Irp
Map_Irp_Bypass
Queue_Dg_Buf
Queue_Mult_Dgs
Recycl_Msg_Bui
Reject

8023222A
8023250C
802322F3
80232730
802325D2
802325B9
802325C2
802325B1
80232512
8023251A
802323F1
802322DA

Recyclh_Msg_Buf
Request.Data
Send.Data
Send_Dg_Buf
Send_Msg_Buf
Send_Cnt_Msg_Buf
Read_Count
Rls_Read_Connt
Mreset
Mstart
Stop_Vcs
Send_Dg_Reg

802323E7
80232677
802326BE
80232570
8023248A
80232491
8023279E
802327DF
802327E8
802327F0
8023281F
80232563

SDA-89

System Dump Analyzer
SHOW PROCESS

SHOW PROCESS
Displays the software and hardware context of any process in the
balance set and performs an implicit SET PROCESS command.

FORMAT

SHOW PROCESS [/qualifier^...]] [parameter]

command
parameters

Shows information about all the processes that exist in the system.

ALL
name
The name of the process that you want to see. Do not use this parameter
with the /SYSTEM or /INDEX= qualifiers. The name can contain up to 15
letters and numerals and can include the underscore (_) and dollar sign ($)
characters. The name must be a quoted string if it contains other than the
foregoing characters.
If you specify no parameter, this command displays information on the
current process. See the description of the SET PROCESS command for the
definition of the current process.

command
qualifiers

/ALL
Displays the information shown by the following qualifiers:
•

/CHANNEL

•

/LOCKS

•

/PCB

•
•
•
•
•

/PHD

•

/REGISTERS
/RMS
/WORKING-SET
/PROCESS-SECTION-TABLE
/PAGE-TABLES

/CHANNEL
Displays the I/O channels assigned to the process, the address of the
window-control block associated with that channel, the status of the channel,
and the specification of the file or device associated with the channel.
The display produced by the SHOW PROCESS/CHANNEL command
contains four columns of information, labeled "channel," "window," "status,"
and "device/file accessed." These columns contain the following information.

SDA-90

System Dump Analyzer
SHOW PROCESS

Column

Contents

Channel

The number of each channel assigned to the
process

Window

The address of the window-control block for the
file. If the device is a file-oriented device, zero
otherwise

Status

The status of the device: "busy" if the device has
an I/O operation outstanding, blank otherwise

Device/file accessed

The name of the device and, if applicable, the
name of the file being accessed on that device

The display varies with the process chosen. SDA displays the information in
the form
dcuu:(file-id)filename
where:
•

dcuu: is the name of the device.

•

file-id is the RMS file identification.

•

filename is the full file specification, including directory name.

SDA displays some or all of this information under the following conditions:
Information Displayed

Type of Process

dcuu:

SDA displays this Information for devices that
are not file structured, such as terminals, and for
processes that do not open files in the normal
way.

dcuu:filename

SDA displays this information only if you are
examining a running system, and only If your
process has enough privilege to translate the
file-id into the file name.

dcuu:(file-id)fllename

SDA displays this information only when you are
examining a dump. The file name corresponds
to the file-id on the device listed. If you are
examining a dump from your own system, the
file name is probably valid. If you are examining
a dump from another system, the file name is
probably meaningless in the context of your
system.

dcuu:(file-id)

The file-id no longer points to a valid file name,
as when you look at a dump from another
system; or the process in which you are running
SDA does not have enough privilege to translate
the file-id Into the corresponding file name

/INDEX=nn
The index of the software process control block (PCB) into the system's PCB
list. Alternatively, this argument can be the process identification (PID or
EPID), from which SDA extracts the index. This index identifies the process
to be displayed.
SDA-91

System Dump Analyzer
SHOW PROCESS

/LOCKS
Displays the locks owned by the current process. See the description of the
SHOW RESOURCE command and its /LOCKID qualifier for a description of
the information displayed by this qualifier.

/PO
Displays the page tables for PO space; must be used with the /PAGE^TABLE
qualifier.

/PI
Displays the page tables for PI space; must be used with the /PAGE—TABLE
qualifier.

/PAGE-TABLES [range]
Displays the page tables of the program and control regions. This qualifier
produces a display in the same format as that of the SHOW PAGE—TABLE
command.
The argument range can have two forms. When you provide an argument of
the form x:y, where x and y are the addresses of virtual pages, this qualifier
displays the page table entries that correspond to the range of pages from x
to y.
When you provide an argument of the form x;y, where x and y are the
addresses of virtual pages, this qualifier displays the page table entries that
correspond to a range of y pages, starting with page x.

/PCB
Produces a list of the data contained in the software process control block
(PCB). The software PCB is the central control mechanism for process
swapping and scheduling.
This qualifier is the default.
The display produced by using the /PCB qualifier lists the following
information:
•

Software context for the process

•

Condition-handling information

•

Information on interprocess communication

•

Information on counts, quotas, and resource usage

/PHD
Lists information included in the process header. The process header contains
the vital statistics of a process and is swapped into memory when a process
becomes part of the balance set. Each item listed by the PHD qualifier gives a
quantity, count, or limit for the process concerning the following resources:

SDA-92

•

Process memory

•

The pager

•

The scheduler

•

Asynchronous system traps

System Dump Analyzer
SHOW PROCESS

•

I/O activity

•

CPU activity

/PROCESS-SECTION^TABLE
Lists the information contained in the process section table. The process
section table contains entries, each of which describes a process section. The
display that this qualifier produces is 132 columns wide.
SDA displays the offsets to the first and last entries in the process section
table under the heading "process section table information," and then displays
the contents of process section table. The following table describes the parts
of each process section table entry contained in the display:
Part

Definition

INDEX

The offset into the section table of the process at which the entry
is found. Because entries in the process section table begin at the
highest location in the table, and the table expands toward lower
addresses, the following expression determines the address of an
entry in the table: PHD + PSTBASOFF—INDEX.

ADDRESS

The virtual address that marks the beginning of the first page of the
section described by this entry.

PAGES

The length, in pages, of the process section.

VBN

Virtual block number, the number of the file's virtual block that is
mapped into the section's first page.

CLUSTER

The cluster size used when faulting pages into this process section.

REFCNT

The number of pages of this section that are currently mapped.

FUNK

Forward link; the pointer to the next entry In the PST list.

BLINK

Backward link; the pointer to the previous entry in the PST list.

FLAGS

The flags that describe the access that processes have to the
process section.

/REGISTERS
Lists the hardware context of the process. When a process executes, its
hardware context is contained in the processor registers (see the description of
the SHOW CRASH command). If the process is not executing, its hardware
context is stored in the hardware PCB, which is part of the process header.
The /REGISTERS qualifier displays the process registers in the following
groups:
•

General registers

•

Stack pointers

•

Special-purpose registers

•

Base and length registers

If the process is the current process in a dump, the current registers are also
displayed.

/RMS[=option]
Displays the RMS data structures for each image-I/O file the process has
open.

SDA-93

System Dump Analyzer
SHOW PROCESS

If you provide the name of a structure as an option, this qualifier displays
only the specified structure for each image-I/O file the process has open.
If you do not specify an option, SDA displays the current list of options as
determined by the last SET RMS command or by SDA when you start it.
See the description of the SET RMS command for the options you can use
with this qualifier.
To show the RMS data structures for process-permanent files, use the
following commands.
SDA> DEFINE SAVE*PIO$GW_IIOIMPA
SDA> DEFINE PIO$GW_IIOIMPA*PIO$GW_PIOIMPA
SDA> SHOW PROCESS/RMS
Process index: 003C

Name: WILLING

IFAB Address: 7FFC6608
PRIMDEV:
BKPBITS:
BLN:
EFN:

08040007
00090006
2E
00

Extended PID: 22E0023C

IFI: 0001

Orgeinization: Sequential

REC.CCL.TRM.AVL.ODV
EOF.PPF.IMAGE,WRTACC.NORECLK
46.
BID:
OB
MODE:
03

11.

/SYSTEM
Displays the system process control block. The system PCB and process
header (PHD) are dummy structures that are located in system space. These
structures contain the system working set, global section table, global page
table, and other systemwide data.

/WORKING-SET
Displays the working-set list for the process. The working-set list is a table
that contains information for all virtual pages that the process can access
without a page fault. This qualifier displays the foilwing information for each
entry in the working-set list:
Column

Contents

INDEX

Index into the working-set list at which information for this entry can
be found

ADDRESS

The virtual address of the page, in the process address space, for
which this entry exists

STATUS

A three-part section that lists the location of the page in physical
memory, the type of page (see the description of the SHOW PAGE_
TABLE command), and whether the page is locked Into the working
set

When SDA locates an unused working-set entry, it issues the message:
- n empty entries

The value of n is the decimal number of contiguous, unused entries that SDA
has found.

SDA-94

Process active channels

Chauinel
0010
0020
0030
0040
0050
0060
0070
0080
0090
OOAO
OOBO
OOCO
OODO
OOEO

Window

Status

Device/file accessed
MBA51:
DBAO:[SYSO.SYSEXE]SDA.EXE;1
DBAO:
DBAO:
MBA44:

00000000
801D3D00
00000000
00000000
00000000
00000000
801B8F40
801B8E20
00000000
801B9060
801B8D00
00000000
801D3A00
00000000

MBA53:
DBAO:[SYS0.001001lLBRSHR.EXE;1
DBAO:[SYS0.001001lDCXSHR.EXE;1

(section file)
(section file)

TTE6:
DBAO:[SYS0.0010013LIBRTL.EXE;1 (section file)
DBAO:[SYS0.0010013SCRSHR.EXE:1 (section file)
TTE6:
DRBO:[WILLING.BOOKS]SDAOUT.TXT;2
TTE6:

The preceding example shows the output of a SHOW P
command used while analyzing a running system. The
the names of the files that are opened because the proc
running has access to the files. If the process has no ac
displays only the device name, the file identification (FI
name.
B

SDA> SHOW PROCESS/CHANNEL
Process index:

0008

Name:

JNLACP

Extended PID:

00000088

Process active channels

Channel

Window

0010
0020
0030
0040
0050
0060
0070
0080
0090

801B11A0
801B11A0
00000000
00000000
00000000
801BD6E0
801B8C40
801B6960
801B6AE0

OOAO

801B1AA0
8016D380

OOBO

Status

Device/file accessed
DBAO:(32,1,0)[SYS0.SYSEXE3F11BXQP.EXE;1
DBAO:(32,1,0)[SYS0.SYSEXE3F11BXQP.EXE;1
DBAO:
DBAO:
MBAll:

(section
(section

DBAO:(252,1,0)[SYSO.SYSEXE]JNLACP.EXE;1
DBAO:(109,1,0)[SYS0.00100l3LIBRTL.EXE;1 (section
DBAO:(99,1,0)[SYSO.001001]DISMNTSHR.EXE:1 (sectio
DBAO:(100,1,0)[SYS0.0010013MOUNTSHR.EXE;1 (sectio
DRA2:(18,36,0)
DRBO:(8757,12,2)[JOURNAL]JWHBI.BIJ;1

The preceding example shows the display produced by
/CHANNEL command while SDA is analyzing a crash
file specification in the display includes the file identific

Internal PID
00080047
Extended PID
00000447
State
HIB
Current priority
5
Base priority
4
UIC
[010,115]
Mutex count
0
Waiting EF cluster
0
Starting wait time
OOOOIBIA
Event flag wait mask
FFBFFFFF
Local EF cluster 0
C8600C06
Local EF cluster 1
00000000
Global cluster 2 pointer 00000000
Global cluster 3 pointer 00000000

Creator internal PID
00070040
Creator extended PID
000003C0
Termination mailbox
06D8
AST's enabled
KESU
AST's active
NONE
AST's remaining
13
Buffered I/O count/limit
6/6
Direct I/O count/limit
6/6
BUFIO byte count/limit
11164/11420
# open files allowed left
18
Timer entries allowed left
10
Active page table count
0
Process WS page count
78
Global WS page count
33

The preceding example shows the output of a SHOW PROCES
command.
SDA> SHOW PROCESS/RMS=IFAB
VAX/VMS 4.4 -- System Dump Analysis

06-JAN-1986 16:12:02.86

Page

Table of Contents
Process index: OOOF

06-JAN-1986 16:12:02.86

VAX/VMS 4.4 -- System Dump Analysis
Page1 2
Process index: OOOF

Name : NETACP

IFAB Address: 7FFA9208
PRIMDEV:
BKPBITS:
BLN
EFN
lOS
I0S4:
IRAB.LNK:
FAC:
ORGCASE:
LAST.FAB:
IFI:
JNLBDB:
BDB..FLNK:
BDB..BLNK:
RFMORG:
RAT
LRL
FFB
FSZ
DEQ
HBK
EBK
RNS._LEN:
SFSB.PTR:
GBSB.PTR:
GBH._PTR:

SDA-96

1C4D4008
02080000
2E
00
00000000
00000000
00000000
00
00
0000A8E4
0001
00000000
7FFA9248
7FFA9248
00
00
0000
0000
00
0000
00000000
00000000
00000000
00000000
00000000
00000000

Name: NETA ....

Extended PID: 21C0010F

IFI: 0001

Organization: Sequential

DIR,FOD,SHR .AVL.ELG.IDV.ODV.RND
NORECLK,SEARCH
OB
BID:
46.
00
MODE:
00000000
ASBADDR:
7FFE7D28
ARGLST:
0060
CHNL:

11.

Sequential
NWA.PTR:
ECHO.ISI:
FWA.PTR:
DEVBUFSIZ:
RTDEQ:

00000000
0000
7FFA9400
0200
0000

512
0.

HBK.DISK:
EBK.DISK:
BKS:
MRS:
GBC:

00000000
00000000
00
0000
0000

0.
0.
0.

LOCK.BDB:
AVLCL:
AVGBPB:
RJB.PTR:

00000000
0000
0000
00000000

UDF
0.
0.
0.
0.
0.
0.

0.
0.

The preceding example shows the output of the SH
/RMS=IFAB command.

System Dump Analyzer
SHOW RESOURCE

SHOW RESOURCE
Displays information on system resources.

FORMAT

SHOW RESOURCE [/qualifier]

command
parameters
command
qualifiers

None.

/ALL
Displays information on all the locks in the system.

/LOCKID=nn
Displays information on the resource associated with the lock with
identification nn.

DESCRIPTION

The SHOW RESOURCE command displays information on system resources.
The following sections discuss each of the displays this command produces.
SHOW RESOURCE/ALL
The display produced by the SHOW RESOURCE/ALL command contains
information as shown in the example following. Descriptions of each item in
the display follow the example. This qualifier is the default.
SDA> SHOW RESOURCE/ALL
Resource database
PW
801FCB40 Group grant mode:
Address of RSB:
00000000 Conversion grant mode:
CR
Parent RSB:
0 BLKAST count:
0
Sub-RSB count:
Value block:
00000000 00000000 00000000 00000000
454F5024 4B534944
DISK$P0E
Resource:
00000000 00000000
.
Length
S
00000000 00000000
.
User mode
00000000 00000000
.
Group
360
Granted queue (Lock ID / Gr mode):
06AB010C

Conversion queue (Lock ID / Gr/Rq mode):
095B00F2

PW/EX

Waiting queue (Lock ID / Rq mode):
054400BC

The definitions of the fields in the display are as follows;

SDA-98

System Dump Analyzer
SHOW RESOURCE

Field

Contents

Address of RSB

The address of the resource block that describes
this resource.

Parent RSB

The resource block that Is the parent of this
resource block. This field is 0 in the example,
which means that this resource block Is a parent
block (is not a child block).

Sub-RSB count

The number of RSBs of which this RSB Is the
parent. This RSB has no "children."

Group grant mode

The most restrictive mode in which a lock on
this resource has been granted. The values that
this field can contain are listed following and
shown in order from the least restrictive to most
restrictive lock modes. The most restrictive lock
granted on this resource is in protected-write
mode. For information on how the lock modes
can conflict with each other, see the VAX/VMS
System Services Reference Manual.
Value

Meaning

Null mode

Concurrent-read mode

Concurrent-write mode

Protected-read mode

Protected-write mode

Exclusive mode

Conversion grant mode

The most restrictive lock mode to which a lock
on this resource Is waiting to be converted. This
does not include the mode for which lock at the
head of the conversion queue is waiting.

BLKAST count

The number of locks on this resource that have
requested a blocking AST.

Value block

A hexadecimal dump of the 16-byte block value
block associated with this resource.

Resource

The beginning of the three-column dump of
the name of this resource, which is stored in
the resource block. The first two columns are
the hexadecimal representation of the name,
with the least significant byte represented by the
rightmost two digits in the righthand column. The
third column contains the ASCII representation
of the name, the least significant byte being
represented by the leftmost character In the
column. Periods in this column represent values
that correspond to unprintable ASCII characters.

Length

The length, in bytes, of the resource block.

SDA-99

System Dump Analyzer
SHOW RESOURCE

Field

Contents

User mode

The processor mode of the name space in which
this resource block resides. In the preceding
example, the resource block resides in the user¬
mode name space. There is a name space for
each processor-access mode.

System

The owner of the resource. In this example the
owner is the system, the VAX/VMS operating
system. When the owner of the resource is a
group, this field contains the number (in octal of
the owning group).

Granted queue

The list of locks on this resource that have
been granted. For each lock in the list, this
display contains the number of the lock and
the lock mode in which the lock was granted.
In the previously shown example, lock number
06AB010C was granted in common-read mode.

Conversion queue

The list of locks waiting to be converted from
one mode to another. For each lock In the list,
this display contains the number of the lock,
the mode in which the lock was granted, and
the mode to which the lock is to be converted.
In the previously shown example, lock number
095B00F2 Is waiting to be converted from
protected-write mode to exclusive-access mode.

Waiting queue

The list of locks waiting to be granted. For each
lock in the list, this display contains the number
of the lock and the mode requested for that
lock. In the previously shown example, lock
number 054400BC is waiting to be granted in
exclusive-access mode.

SHOW RESOURCE/LOCKID
The SHOW RESOURCE/LOCKID command shows information on the
resource locked by the lock identified by the parameter to the /LOCKID
qualifier. The following example shows the information contained in the
display produced by this qualifier. A description of each item in the display
follows the example.
SDA> SHOW PR0CESS/L0CKS/INDEX»8
Process index: 0008

Name: JOB.CONTROL

Extended PID: 22A00088

Lock data:
Lock id:
11A00117
PID:
00010008
NL
Par. id:
007B0004
Gr2Lnted at
Sublocks:
0
LKB:
801F9B40
Resource:
00000000 0000018C
Length
04
00000000 00000000
Exec, mode
00000000 00000000
System
00000000 00000000

SDA-100

Flags:

CONVERT SYNCSTS SYSTEM

Status:

System Dump Analyzer
SHOW RESOURCE

PID:
00010008
Flags:
VALBLK
Lock id:
007B0004
Granted at
CR
SYSTEM
Par. id:
00000000
Sublocks:
16
LKB:
801E9100
Resource:
00000014 03BA0001
.
Status:
Length
19
44244854 4E694C50
PLYNTH$D
Exec, mode
00000000 00304155
UAO.
System
00000000 00000000
.

CONVERT SYNCSTS

The information in the display is described as follows:

Display Element

Description

Process Index

The index into the PCB array at which you find a pointer
to the PCB of the process that owns the lock.

Name

The name of the process that owns the lock.

Extended PID

The clusterwide identification of the process that owns
this lock.

Lock Data

The heading of the section of the display that contains
the information on the lock.

Lock id

The identification of the lock.

PID

The processor-wide identification of the lock.

FLAGS

Information specified in the request for the lock.

Par id

The identification of this lock's parent lock.

Granted at

The lock mode at which this lock was granted.

Sublocks

The identification numbers of the locks that this lock
owns.

LKB

The address of the lock block, a block of memory In
nonpaged dynamic pool in which the Information on this
lock is stored.

Resource

A dump of the resource block. The two lefthand columns
show the contents of the resource block as hexadecimal
values, the least significant byte being represented by
the rightmost two digits. The righthand column shows
the contents of the resource block as ASCII text, the
least significant byte being represented by the leftmost
character.

Length

The length, in bytes, of the lock block.

System

The owner of the lock. This lock is owned by the
VAX/VMS operating system. Locks owned by a group
have the number of the owning group in this field.

Status

The status of the lock, information used internally by the
VAX/VMS lock manager.

The two columns of hexadecimal numbers are a dump of the lock block. The
column of ASCII characters to the right of the hexadecimal columns is the
ASCII representation of the dump of the lock block.

SDA~101

System Dump Analyzer
SHOW RMS

SHOW RMS
Displays the names of the VAX RMS data structures that the SHOW
PROCESS/RMS command displays.

FORMAT

SHOW RMS

command
parameters
command
qualifiers

None.

DESCRIPTION

This command shows names of the data structures that the SHOW PROCESS
/RMS command displays. The SET RMS command determines which data
structures SHOW PROCESS/RMS displays. See the description of the SET
RMS command for the names of the VAX RMS data structures that this
command can display.

None.

EXAMPLE
SDA> SHOW RMS
RMS Display Options: IFB,IRB,IDX,BDB,BDBSUM,ASB,CCB,WCB,FOB.FAB,RAB,
NAM.XAB.RLB,BLB.BLBSUM,GBD.GBH,TRC,FWA,GBDSUM.RJB
Display RMS structures for all IFI values.

The preceding example shows how the SHOW RMS command displays the
data structures to be displayed by the SHOW PROCESS/RMS command.

SDA-102

System Dump Analyzer
SHOW RSPID

SHOW RSPID
Displays information about response-IDs (RSPIDs). Whenever a
local system application (SYSAP) requires a response from a remote
SYSAP, a unique number is assigned by the local system and is
called an RSPID. The RSPID is transmitted in the original request (as
a means of identification), and the remote SYSAP returns the same
RSPID in its response to the original request.

FORMAT

SHOW RSPID

command
parameters
command
qualifiers

None.

/CONNECTION=n
Displays RSPID information for the specific SCS connection whose connection
descriptor table (CDT) address is given. The value that you specify to
obtain information for a specific CDT is obtained either by using the SHOW
CONNECTIONS command or by examining an appropriate data structure.

DESCRIPTION The SHOW RSPID command displays information about the response-ID
descriptor table, which lists the currently open requests that require responses
from remote SYSAPs. For each request that a local SYSAP transmits that
requires a response from a remote SYSAP, VAX/VMS generates a unique
identifying number that is assigned to that request, and that identifying
number is called a response-ID (RSPID).VAX/VMS can associate a specific
RSPID with the request that caused the RSPID to be generated, and the
SHOW RSPID command provides information about RSPIDs that are
currently in use (in other words, currently outstanding requests from local
SYSAPs to remote SYSAPs).
The display for the SHOW RSPID command, shown in the following
example, lists a summary of the current response descriptor table. For each
RSPID, this summary includes the following;
•

The RSPID value

•

The address of the class driver request packet (CDRP, which generally
represents the original request)

•

The address of the CDT that is using the RSPID

•

The name of the local process using the RSPID

•

The remote node from which a response is required (and has not been
received).

To obtain information about RSPIDs in use for a specific connection, use the
/CONNECTION= qualifier and the associated CDT address.

SDA-103

F8680001
F8070002
F80D0003

80336B00
80422A00
80393C60

SDA-104

801C2850
801C28F0
801C2850

VMS$DISK_CL_DRVR
VMS$VAXcluster
VMS$DISK_CL_DRVR

PINTO
SOLLY
PINTO

System Dump Analyzer
SHOW STACK

SHOW STACK
Displays the location and contents of the four process stacks and
the systemwide interrupt stack.

FORMAT
command
parameter

command
qualifiers

SHOW STACK

[/qualifierf,...]] [range]

range
The range of memory locations you want to display in stack format. You can
express the range as two locations separated by a colon (:), or as a location
and a length, in bytes, separated by a semicolon (;).

/EXECUTIVE
Shows the executive-mode stack for the current process.

/INTERRUPT
Shows the interrupt-mode stack.

/KERNEL
Shows the kernel-mode stack for the current process.

/SUPERVISOR
Shows the supervisor-mode stack for the current process.

/USER
Shows the user-mode stack for the current process.

DESCRIPTION

Each qualifier displays one of four stacks that correspond to the four
VAX/VMS processor access modes for the current process as specified
by the most recent SET PROCESS or SHOW PROCESS command. The
/INTERRUPT qualifier displays the systemwide interrupt stack. The default
for SHOW STACK is the stack that is currently being used or that was in use
when the system failed.
The following example shows the display produced by the SHOW STACK
command. The display is the same for each stack and is composed of the
following four sections.

SDA-105

System Dump Analyzer
SHOW STACK

Section

Contents

Stack pointer

The stack pointer identifies the top of the stack. The
display indicates the stack pointer by the symbol SP => .

Stack address

SDA lists all the virtual addresses that the operating system
has allocated to the stack. The stack addresses are listed
in a column that increases in increments of 4 bytes (one
longword).

Stack contents

SDA lists the contents of the stack in a column next to the
stack addresses.

Symbols

SDA attempts to display the contents of a location
symbolically, using a symbol and an offset, as shown
In the example following.
If the address Is not within FFF (hexadecimal) of the value
of any existing symbol, the field Is left blank.

If a Stack is empty, the display shows:
SP =>

(THE STACK IS EMPTY)

If you give a range of memory locations as a parameter to the SHOW STACK
command, SDA displays that range in stack format.

EXAMPLE
SDA> SHOW STACK
Current operating stack
Current operating stack (USER):
7FF73278
7FF7327C
7FF73280
7FF73284

200C0000
00001618
7FF732F0
000187A7

7FF73288
7FF7328C
7FF73290
7FF73294
7FF73298

0000060A
00000000
00000003
7FF73800
7FF73800

SGN$C_MAXPGFL+618
RMS$_ECH0+72E
BUG$_N0HDJMT+002

The preceding example shows the output from a SHOW STACK command.
The data shown above the stack pointer may not be valid. The symbol to
the right of the columns, BUG$_NOHDJMT+002, is the result of the SDA
attempt to interpret the contents of the longword at the top of the stack as a
symbol meaningful to the user. In this case the value on the stack and the
value of BUG$_NOHDJMT are unrelated.

SDA-106

System Dump Analyzer
SHOW SUMMARY

SHOW SUMMARY
Displays a list of all active processes and the values of the
parameters used in swapping and scheduling these processes.

FORMAT

SHOW SUMMARY

command
parameters
command
qualifier

None.

DESCRIPTION

/IMAGE
This qualifier causes SDA to provide an extra line for every process in the
display that SHOW SUMMARY produces. The line contains the name of the
image, if available, being executed within each process.

The following example shows the display produced by the SHOW
SUMMARY command.

Column

Contents

Indx

The

Extended PID

The

Process name

The

Username

The

SDA-107

System Dump Analyzer
SHOW SUMMARY

Column

Contents

State

The current state of the process, one of 14 states

State

Meaning

COM

Computable and resident in memory

COMO

Computable, but outswapped

CUR

Currently executing

CEF

Waiting for a common event flag

LEF

Waiting for a local event flag

LEFO

Outswapped and waiting for a local event flag

HIB

Hibernating

HIBO

Hibernating and outswapped

SUSP

Suspended

SUSPO

Suspended and outswapped

PFW

Waiting for a page that is not in memory (page-fault
wait)

FPG

Waiting to add a page to its working set (free-page
wait)

COLPG

Waiting for a page collision to be resolved (collidedpage wait); this usually occurs when several
processes cause page faults on the same shared
page

MWAIT

Waiting for a system resource (miscellaneous wait)

Pri

The current scheduling priority of the process

PCB

The address of the control block for this process

PHD

The address of the header for this process

Wkset

The number (decimal) of pages currently in the working set of
the process

EXAMPLE
SDA> SHOW SUMMARY
Extended Indx Process name Username State Pri
00000080
00000081
00000083
00000087

0000
0001
0003
0007

NULL
SWAPPER
DBAOBACP
OPCOM

SYSTEM
SYSTEM

COM
HIB
HIB
LEF

0
16
10
7

PCB

PHD

80001EA0
80002168
800DD330
800DDB90

80001D28
80001FF0
80202400
80332200

Wkset
0
0
469
90

The SHOW SUMMARY command displays a summary description of all the
processes that existed on the system at the time of the system failure. The
display is the same as that produced by the DCL command SHOW SYSTEM.

SDA-108

System Dump Analyzer
SHOW SYMBOL

SHOW SYMBOL
Displays the value of a symbol and the contents of the location that
has an address equal to the value of that symbol.

FORMAT
command
parameter
command
qualifier

SHOW SYMBOL [/qualifierf,...]] parameter
symbol-name
The name of the symbol of interest. You must provide the name of the
symbol.

/ALL
Displays information on all the symbols whose names match the characters
specified in the command parameter and are defined in the SDA symbol
table. If you use this qualifier, you can provide part of the name of a symbol,
and SDA will display all symbols that start with the string you specify.

EXAMPLES
□

SDA> SHOW SYMBOL G
G = 80000000 :
8FBC0FFC

This command shows two items: G has a value of 80000000, and at address
80000000 is the quantity 8FBC0FFC (hexadecimal).
S

SDA> SHOW SYMBOL/ALL I0C$GL_
Symbols sorted by name
I0C$GL_ADPLIST
I0C$GL_AQBLIST
I0C$GL_CRBTM0UT
I0C$GL_DEVLIST

80000E58
800027B0
800027C4
80000EBC

=>
=>
=>
=>

801F4000
8020C080
801F5694
80000ECC

I0C$GL_SRPSIZE 80002764 => 00000080
IOC$GL_SRPSPLIT 8000276C => 801F4000
IOC$GL_TU_CDDB 800027CC => 00000000

The preceding example shows the display produced by the SHOW SYMBOL
/ALL command. SDA searches its symbol table for all symbols that begin
with the string "IOC$GL_" and displays the symbols, their values, and the
contents of the locations addressed by those values.

SDA-109

System Dump Analyzer
SPAWN

SPAWN
Creates a subprocess of the current process. The system copies
the context of the subprocess from the current process. The
subprocess executes the command that you specify in the SPAWN
command.

FORMAT

SPAWN [/qualifier[,...]] [command]

command
parameter

The name of the command that you want executed by the subprocess.

command
qualifiers

command
/INPUT=filespec
Specifies an input file containing one or more command strings to be executed
by the spawned subprocess. If you specify a command string with an input
file, the command string is processed before the commands in the input file.
Once processing is complete, the subprocess is terminated.

/NOLOGICAL-NAMES
Specifies that the logical names of the parent process are not to be copied to
the subprocess. The default behavior is that the logical names of the parent
process are copied to the subprocess.

/NOSYMBOLS
Specifies that the DCL global and local symbols of the parent process are not
to be passed to the subprocess. The default behavior is that these symbols
are passed to the subprocess.

/NOTIFY
Specifies that a message is to be broadcast to SYS$OUTPUT when the
subprocess completes processing or aborts. The default behavior is that such
a message is not sent to SYS$OUTPUT.

/NOWAIT
Specifies that the system is not to wait until the subprocess is completed
before allowing more commands to be specified. This qualifier allows you
to specify new commands while the spawned subprocess is running. If
you specify /NOWAIT, you should use /OUTPUT to direct the output of
the subprocess to a file in order to prevent more than one process from
simultaneously using your terminal.
The default behavior is that the system waits until the subprocess is
completed before allowing more commands to be specified.

SDA-110

System Dump Analyzer
SPAWN

/OUTPUT=filespec
Specifies an output file to which the results of the SPAWN operation are
written. You should specify an output other than SYS$OUTPUT whenever
you specify /NOWAIT to prevent output from the spawned subprocess from
being displayed while you are specifying new commands. If you omit the
/OUTPUT qualifier, output is written to the current SYS$OUTPUT device.

/PROCESS=process—name
Specifies the name of the subprocess to be created. The default name of the
subprocess is USERNAME_n, where USERNAME is the user name of the
parent process.

SDA-111

System Dump Analyzer
VALIDATE QUEUE

VALIDATE QUEUE
Validates the integrity of the specified queue by checking the
pointers in the queue.

FORMAT
command
parameter

VALIDATE QUEUE [address]

address
The address is the address of an element of the queue. If the address is not
specified, then the last element address that was specified (in a previous
VALIDATE QUEUE command) is used. If a dot is specified as the address,
then the last evaluated expression is used as the address of an element of the
queue.

command
qualifiers

/SELF-RELATIVE

DESCRIPTION

The VALIDATE QUEUE command uses the forward and backward pointers
in each element of the queue to make sure that the pointers are all valid and
that the integrity of the queue is intact. If the queue is intact, SDA displays
the following message:

Specifies that the selected queue is a self-relative queue.

Queue is complete, total of n elements in the queue

If SDA discovers an error in the queue, it displays this message:
Error comparing backward link to previous structure address
mmmmmmmm.
Error occurred in queue element at address nnnnnnnn.
after tracing n elements.

Address mmmmmmmm is the address you gave as the argument to the
VALIDATE QUEUE command; address nnnnnnnn is the address of the queue
element in which the error was detected.
If there are no entries in the queue, SDA displays this message:
The queue is empty

If you do not specify an address to the VALIDATE QUEUE command, the
following action is taken:

SDA-112

•

If a queue has previously been used in the current SDA session, that
queue is used.

•

The previous evaluated expression is used as an address if you specify a
period (.) after the VALIDATE QUEUE command.

•

If no queue has previously been specified, and you do not use a period
after the command, an error message is displayed indicating that no queue
has been specified for validation.

System Dump Analyzer
VALIDATE QUEUE

EXAMPLE
SDA> VALIDATE QUEUE IOC$GL_IRPFL
Error comparing backwsurd link to previous structure address (801E6200)
Error occured in queue element at address 801CA000. after tracing 399 elements
SDA> VALIDATE QUEUE IOC$GL_IRPFL
Queue is complete, total of 404 elements in the queue

The preceding example shows the display produced by the VALIDATE
QUEUE command. The preceding example was produced on a running
system, and the queue changed during the SDA attempt to validate it. Thus
the error message. The second command was successful, and the queue was
complete.

SDA-113

Index

A
Access violation •SDA-16
Addition operator*SDA-12
/ADDRESS qualifier*SDA-68, SDA-73, SDA-89
/ALL qualifier *SDA-41, SDA-79, SDA-80, SDA84, SDA-90, SDA-98, SDA-109
ANALYZE command * SDA-1
AP symbol*SDA-13
Argument pointer*SDA-13
Arithmetic shifting operator*SDA-12
Array
mechanism * SDA-16
signal * SDA-16, SDA-18
At-sign (@) character*SDA-12
At-sign (@) operator*SDA-12
ATTACH command * SDA-32

B
/BAD qualifier*SDA-84
Base register*SDA-13
Bugcheck
fatal conditions*SDA-15
halt/restart * SDA-9
Bugcheck code*SDA-14

C
/CHANNEL qualifier*SDA-90
CLUSTRLOA symbol * SDA-13
CMKRNL privilege*SDA-9
Command
abbreviating * SDA-10
command qualifiers*SDA-11
comment * SDA-11
format of*SDA-10
parameters* SDA-11
Command format
general * SDA-10
/CONDITION_V ALUE qualifier * SDA-38
/CONDITION qualifier*SDA-18
/CONNECTION qualifier * SDA-103

COPY command • SDA-33
/CRASH_DUMP qualifier•SDA-I
/CSID qualifier*SDA-64

D
DEFINE command *SDA-34
Device driver
finding a failing * SDA-22
Display * SDA-9
Division operator*SDA-12
DPT base address*SDA-22
Driver offset * SDA-23
DUMPBUG system parameter * SDA-5
Dump file
analyzing* SDA-1
copying *SDA-6
default *SDA-8
flag*SDA-7
mapping * SDA-9
saving * SDA-6
size of the*SDA-6
system * SDA-4
writing the*SDA-5

E
/ECHO qualifier *SDA-35
ESP symbol*SDA-13
EVALUATE command * SDA-38
EXAMINE command * SDA-41
Exception
fatal* SDA-15
Identifying causes of*SDA-20
Execute procedure for SDA*SDA-31
Executive-mode stack pointer*SDA-13
/EXECUTIVE qualifier*SDA-105
EXIT command *SDA-45
Expression * SDA-11
negating* SDA-12

Index—1

Index

FORMAT command • SDA-46
FP symbol •SDA-13
Frame pointer •SDA-13
/FREE qualifier •SDA-84, SDA-87

Length register •SDA-13
Listing
output •SDA-?
Location indicator
current •SDA-13
/LOCKID qualifier • SDA-98
/LOCKS qualifier •SDA-92
/LRP qualifier• SDA-87

G character • SDA-13
/GLOBAL qualifier •SDA-80
G operator •SDA-12
G symbol •SDA-13

H character •SDA-13
/HEADER qualifier •SDA-87
HELP command •SDA-48
H operator •SDA-12
H symbol •SDA-13

M
MCHK symbol •SDA-13
Memory location
decoding • SDA-43
examining • SDA-42
Memory region
examining • SDA-43
/MODIFIED qualifier •SDA-84
Module
finding a failing • SDA-22
MP symbol • SDA-13
MSCP symbol •SDA-13
Multiplication operator • SDA-12

I
/IF_STATE qualifier •SDA-35
/IMAGE qualifier •SDA-107
/INDEX qualifier•SDA-BS, SDA-91
Initialization flle^SDA-8
/INPUT qualifier • SDA-110
/INSTRUCTION qualifier • SDA-41
/INTERRUPT qualifier •SDA-105
/IRP qualifier •SDA-87

Kernel-mode stack pointer •SDA-13
/KERNEL qualifier •SDA-105
/KEY qualifier •SDA-35
KSP symbol •SDA-13

Index—2

nnDRIVER symbol • SDA-13, SDA-22
/NOLOGICAL_NAMES qualifier• SDA-110
/NONPGED qualifier •SDA-87
/NOPSUPPRESS qualifier •SDA-42
/NOSKIP qualifier •SDA-42
/NOSYMBOLS qualifier • SDA-110
/NOTIFY qualifier • SDA-110
/NOWAIT qualifier • SDA-110

Index

Operator (cont'd.)
H»SDA-12
precedence of»SDA-12
radix»SDA-11
unary • SDA-12
/OUTPUT qualifier •SDA-110

p
POBR symbol*SDA-13
POLR symbol*SDA-13
/PO qualifier*SDA-92
P1BR symbol*SDA-13
P1LR symbol*SDA-13
/PI qualifier*SDA-42, SDA-92
/PAGE_TABLES qualifier * SDA-92
/PAGED qualifier *SDA-87
Page fault *SDA-20
illegal* SDA-19
PAGEFILE.SYS file*SDA-5, SDA-6, SDA-7
Page table entry
evaluate *SDA-38
Paging file*SDA-5, SDA-6, SDA-7
quota * SDA-8
/PARENT qualifier *SDA-32
PC (program counter)
contents * SD A-15
symbol* SDA-13
/PCB qualifier*SDA-92
PGFLOUOTA system parameter*SDA-8
/PHD qualifier*SDA-92
Precedence of operators*SDA-12
Privileged information * SDA-8
Process
stalled *SD A-10
/PROCESS_SECTION_TABLE qualifier * SDA-93
Process context
default * SDA-9
Processor status longword
See PSL
/PROCESS qualifier*SDA-11 1
Program counter
See PC
PSL (processor status longword)
examining * SDA-44
symbol* SDA-13
/PSL qualifier*SDA-42
/PTE qualifier*SDA-38, SDA-42

R
Radix
default* SDA-11
operator* SDA-11
READ command * SDA-49
SYS$DISK*SDA-49
Redirecting output * SDA-10
Register* SDA-13
base* SDA-13
contents destroyed * SDA-9
length* SDA-13
/REGISTERS qualifier * SDA-93
Register symbol * SDA-13
/RELOCATE qualifier * SDA-49
REPEAT command *SDA-51
/RMS qualifier*SDA-93
RMS symbol * SDA-13

s
SO base address*SDA-13
SAVEDUMP parameter *SDA-6
Scheduler states * SDA-10
SCSLOA symbol*SDA-13
/SCS qualifier *SDA-64
SDA$INIT logical name*SDA-8
SEARCH command *SDA-52
/SELF_RELATIVE qualifier * SDA-112
/SET_STATE qualifier * SDA-35
SET LOG command *SDA-54
SET NOLOG command *SDA-55
SET OUTPUT command*SDA-10, SDA-56
SET PROCESS command * SDA-58
SET RMS command *SDA-60
SHOW CLUSTER command * SDA-64
SHOW CONNECTIONS command * SDA-68
SHOW CRASH command *SDA-70
SHOW DEVICE command *SDA-73
SHOW HEADER command * SDA-78
SHOW LOCK command *SDA-79
SHOW PAGE_TABLE command * SDA-80
SHOW PFN_DATA command * SDA-84
SHOW POOL command * SDA-87
SHOW PORTS command *SDA-89
SHOW PROCESS command *SDA-90
SHOW RESOURCE command * SDA-98
SHOW RMS command*SDA-102
SHOW RSPID command*SDA-103

Index—3

Index

SHOW STACK command‘SDA-105
SHOW SUMMARY command • SDA-107
SHOW SYMBOL command‘SDA-109
SP (stack pointer)
executive-mode • SD A-13
kernel-mode • SDA-13
supervisor-mode • SDA-14
symbol •SDA-14
user-mode • SDA-14
SPAWN command*SDA-110
SPR (Software Performance Report) • SDA-5
SPT
See System page table
SPT (system page table) • SDA-9
/SRP qualifier •SDA-S?
SSP symbol •SDA-14
Stack pointer
See SP
Startup procedure*SDA-6, SDA-7
Subtraction operator*SDA-12
/SUMMARY qualifier *SDA-87
/SUPERVISOR qualifier*SDA-105
Symbol* SDA-13
AP*SDA-13
CLUSTRLOA*SDA-13
ESP*SDA-13
for register*SDA-13
FP*SDA-13
G*SDA-13
H*SDA-13
KSP*SDA-13
MCHK*SDA-13
MP*SDA-13
MSCP*SDA-13
nnDRIVER*SDA-13, SDA-22
P0BR*SDA-13
P0LR*SDA-13
P1LR*SDA-13
PC* SDA-13
PSL*SDA-13
RMS* SDA-13
SCSLOA*SDA-13
SP*SDA-14
SSP*SDA-14
SYSLOA*SDA-14
USP*SDA-14
/SYMBOL qualifier for symbol table*SDA-1
/SYMBOLS qualifier for EVALUATE * SDA-38
Symbol table*SDA-13
SDA*SDA-10
SYS.STB*SDA-10

Symbol table (cont'd.)
SYSDEF.STB*SDA-10
system* SDA-10
SYS.MAP file*SDA-15
SYS.STB file*SDA-10
SYS$DISK as SDA output * SDA-56
SYSSDISK global read*SDA-49
SYSDUMP.DMP file*SDA-4, SDA-5, SDA-7
SYSLOA symbol*SDA-14
SYSTARTUP.COM * SDA-7
System
analyzing a running*SDA-1, SDA-9
hung * SDA-26
management * SDA-5
performance problems*SDA-9
System dump
analyzing *SDA-8
System failure*SDA-5
analyzing*SDA-14, SDA-20
causing* SDA-26
diagnosing * SDA-14
/SYSTEM qualifier*SDA-1, SDA-42, SDA-58,
SDA-80, SDA-84, SDA-94

T
/TERMINATE qualifier * SDA-35
/TIME qualifier*SDA-42
/TYPE qualifier *SDA-46, SDA-88

u
Unary operator*SDA-12
/USER qualifier*SDA-105
USP symbol*SDA-14

V
VALIDATE QUEUE command * SDA-112
Virtual address space
size* SDA-8
VIRTUALPAGECNT system parameter*SDA-8

w
/WORKING_SET qualifier * SDA-94

Index—4

VAX/VMS System Dump Analyzer
Reference Manual
AA-Z429C-TE

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III
Do Not Tear - Fold Here

MMllM..l.ll.l..l.lnl.lMll.Ml