Order Number: BA554-90003
This manual describes the OpenVMS DELTA and XDELTA debuggers. OpenVMS DELTA is used to debug programs that run in privileged processor mode at interrupt priority level 0. OpenVMS XDELTA is used to debug system software that runs at an elevated interrupt priority level.
This manual supersedes the HP OpenVMS Delta/XDelta Debugger Manual, OpenVMS I64 Version 8.2
OpenVMS Alpha Version 7.3
OpenVMS VAX Version 7.3
OpenVMS I64 Version 8.3 OpenVMS Alpha Version 8.3
Hewlett-Packard Company Palo Alto, California
© Copyright 2006 Hewlett-Packard Development Company, L.P.
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Printed in the US.
The HP OpenVMS documentation set is available on CD-ROM.
This manual is written for programmers who debug system code for device drivers and other images that execute in privileged processor-access modes or at an elevated interrupt priority level (IPL).
This manual consists of the following chapters and appendixes:
This manual refers to several documents that contain the primary descriptions of topics discussed in this manual. The following table lists the topics and those documents.
|Accessing OpenVMS VAX through a lower priority interrupt level
|HP OpenVMS System Manager's Manual
|Boot command qualifiers for Volume Shadowing
|HP Volume Shadowing for OpenVMS
|Device name parameters
|HP OpenVMS System Manager's Manual
IPRs for OpenVMS Alpha
PALcode opcodes for OpenVMS Alpha
|Alpha Architecture Reference Manual
|Intel® Itanium® hardware architecture and environment
|Intel® IA-64 Architecture Software Developer's Manual Volume 1: IA-64 Application Architecture
|Intel® IA-64 Architecture Software Developer's Manual Volume 2: IA-64 System Architecture
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OSSG Documentation Group, ZKO3-4/U08
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For information about how to order additional documentation, visit the following World Wide Web address:
The following conventions are used in this manual:
|Abbreviation representing "HP OpenVMS for Integrity servers".
|A sequence such as Ctrl/ x indicates that you must hold down the key labeled Ctrl while you press another key or a pointing device button.
|A sequence such as PF1 x indicates that you must first press and release the key labeled PF1 and then press and release another key or a pointing device button.
In examples, a key name enclosed in a box indicates that you press a
key on the keyboard. (In text, a key name is not enclosed in a box.)
In the HTML version of this document, this convention appears as brackets, rather than a box.
A horizontal ellipsis in examples indicates one of the following
|A vertical ellipsis indicates the omission of items from a code example or command format; the items are omitted because they are not important to the topic being discussed.
|In command format descriptions, parentheses indicate that you must enclose choices in parentheses if you specify more than one.
|In command format descriptions, brackets indicate optional choices. You can choose one or more items or no items. Do not type the brackets on the command line. However, you must include the brackets in the syntax for OpenVMS directory specifications and for a substring specification in an assignment statement.
|In command format descriptions, vertical bars separate choices within brackets or braces. Within brackets, the choices are optional; within braces, at least one choice is required. Do not type the vertical bars on the command line.
|In command format descriptions, braces indicate required choices; you must choose at least one of the items listed. Do not type the braces on the command line.
|This typeface represents the introduction of a new term. It also represents the name of an argument, an attribute, or a reason.
|Italic text indicates important information, complete titles of manuals, or variables. Variables include information that varies in system output (Internal error number), in command lines (/PRODUCER= name), and in command parameters in text (where dd represents the predefined code for the device type).
|Uppercase text indicates a command, the name of a routine, the name of a file, or the abbreviation for a system privilege.
Monospace type indicates code examples and interactive screen displays.
In the C programming language, monospace type in text identifies the following elements: keywords, the names of independently compiled external functions and files, syntax summaries, and references to variables or identifiers introduced in an example.
|A hyphen at the end of a command format description, command line, or code line indicates that the command or statement continues on the following line.
|All numbers in text are assumed to be decimal unless otherwise noted. Nondecimal radixes---binary, octal, or hexadecimal---are explicitly indicated.
This chapter presents an overview of the DELTA and XDELTA debuggers, and provides the following information:
The DELTA and XDELTA debuggers are used to monitor the execution of user programs and the OpenVMS operating system. They use the same commands and the same expressions, but they differ in how they operate. DELTA operates as an exception handler in a process context. XDELTA is invoked directly from the hardware SCB vector in a system context.
Use DELTA to debug process-context programs that execute at interrupt priority level (IPL) 0 in any processor mode. You cannot use DELTA to debug code that executes at an elevated IPL. To debug with DELTA, invoke it from within your process by specifying it as the debugger (as opposed to the symbolic debugger).
Use XDELTA to debug system software executing in any processor mode or
at any IPL level. Because XDELTA is not process specific, it is not
invoked from a process. To debug with XDELTA, you must boot the
processor with commands to include XDELTA in memory. XDELTA's existence
terminates when you reboot the processor without XDELTA.
1.2 Privileges Required for Running DELTA
No privileges are required to run DELTA to debug a program that runs in user mode. To debug a program that runs in other processor-access modes, the process in which you run the program must have the necessary privileges.
To use the ;M command, your process must have change-mode-to-kernel (CMKRNL) privilege. The ;M command sets all processes writable.
To use the ;L command (List All Loaded Executive Modules), you must
have change-mode-to-executive (CMEXEC) privilege.
1.3 Guidelines for Using XDELTA
Because XDELTA is not process specific, privileges are not required.
When using XDELTA, you must use the console terminal. You should run XDELTA only on a standalone system because all breakpoints are handled at IPL 31.
You cannot redirect output from XDELTA. To determine if your system
maintains a log file, check your hardware manual. You can produce a log
of console sessions by connecting the console serial port of the system
that will boot with XDELTA to the serial port of a LAT server. Then,
from another system, use the command SET HOST/LAT/LOG to that LAT port.
1.4 Restrictions for XDELTA on OpenVMS I64 Systems
The following Intel® Itanium® hardware registers are not supported by XDELTA on OpenVMS I64 systems:
To invoke DELTA, perform the following steps after assembling (or compiling) and linking your program:
$ DEFINE LIB$DEBUG SYS$LIBRARY:DELTA
$ RUN/DEBUG MYPROG
When DELTA begins execution, it displays its name and the first executable instruction in the program with which it is linked. It displays the address of that instruction, a separator---an exclamation point (!) on I64 and Alpha, and a slash (/) on VAX---and the instruction and its operands.
On I64, the name and starting address are displayed as follows:
hp OpenVMS Industry Standard 64 DELTA Debugger Brk 0 at address address! instruction operands
On Alpha, the name and starting address are displayed as follows:
OpenVMS Alpha DELTA Debugger Brk 0 at address address! instruction operands
On VAX, the name, current version number, and address are displayed as follows:
DELTA Version 5.5 address/instruction operands
DELTA is then ready for your commands.
You can redirect output from a DELTA debugging session by assigning DBG$DELTA to the I/O device.
The image activator on OpenVMS Alpha systems automatically activates SYS$SHARE:SYS$SSISHR.EXE when an image is debugged using the RUN/DEBUG command or is linked using the /DEBUG qualifier. The presence of this image should not alter your program's correctness, but if your program is sensitive to virtual address layout or if for some reason SYS$SHARE:SYS$SSISHR.EXE is not installed properly on your system, you may want to bypass its automatic activation.
To keep the image activator from activating SYS$SHARE:SYS$SSISHR.EXE for you, define the logical name SSI$AUTO_ACTIVATE to be "OFF" before running the program to be debugged with DELTA.
To exit from DELTA, type EXIT and press the Return key. When you are in
user mode, you exit DELTA and your process remains. When you are in a
privileged access mode, your process can be deleted.
1.7 Invoking XDELTA
To invoke XDELTA, perform the following steps:
1 BRK at address address/instruction
Never clear breakpoint 1 from any code being debugged in XDELTA. If you accidentally clear breakpoint 1 and no other breakpoints are set, you cannot use XDELTA until you reboot again with XDELTA.
BRK 0 at address address!instruction
On VAX, the procedure for booting the system with XDELTA differs, depending on the model of your system. Each procedure uses commands that include XDELTA in memory and cause the execution of a breakpoint in OpenVMS initialization routines. Execution of the breakpoint instruction transfers program control to a fault handler located in XDELTA.
Some boot procedures require the use of the /R5 qualifier with the boot command. The /R5 qualifier enters a value for a flag that controls the way XDELTA is loaded. The flag is a 32-bit hexadecimal integer loaded into R5 as input to VMB.EXE, the primary boot program. For a description of the valid values for this flag, see Table 1-1.
When you deposit a boot command qualifier value in R5, make sure that any other values you would normally deposit are included. For example, if you were depositing the number of the system root directory from which you were booting and an XDELTA value, R5 would contain both values.
For directions for booting XDELTA on VAX, see the OpenVMS VAX supplement specific to your computer.
On Alpha, the procedure for booting all Alpha systems with XDELTA is the same. For one example of how to boot XDELTA, use the boot command as follows:
>>> BOOT -FLAG 0,6
On I64, the procedure for booting with XDELTA is the same. For an example of how to boot XDELTA, use the boot command as follows:
fs0:\efi\vms\> vms_loader -fl 0,6
On I64 and Alpha, the flag for specifying boot qualifiers is a 64-bit integer that is passed directly as input to the primary boot program; IPB.EXE on I64 and APB.EXE on Alpha. For a description of the valid values for this flag, see Table 1-1.
|Normal, nonstop boot (default)
|Stop in SYSBOOT
|Include XDELTA, but do not take the initial breakpoint
|Stop in SYSBOOT, include XDELTA, but do not take the initial breakpoint
|Include XDELTA, and take the initial breakpoint
|Include XDELTA, stop in SYSBOOT, and take the initial breakpoint at system initialization
If you set the boot control flag to 6, XDELTA will stop at an initial breakpoint during the system boot process. You can then set other breakpoints or examine locations in memory.
Your program can also call the routine INI$BRK, which in turn executes the first XDELTA breakpoint. For the breakpoint procedure, see Section 1.9.
Once loaded into memory, XDELTA can also be invoked at any time from the console by requesting a software interrupt. For example, you might need to use a software interrupt to enter XDELTA if your program is in an infinite loop or no INI$BRK call had been made.
On VAX, INI$BRK is defined as XDELTA's breakpoint 1.
On VAX, never clear breakpoint 1 from any code being debugged in XDELTA. If you accidentally clear breakpoint 1 and no other breakpoints are set, you cannot use XDELTA again until you reboot with XDELTA.
On I64 and Alpha, INI$BRK is defined as XDELTA's breakpoint 0. It is not possible to clear breakpoint 0 from any code being debugged in XDELTA.