Debugging with GDB (February 2008)

ManualsBrandsHP ManualsSoftwareHP-UX Debugging Tools

171

172

173

174

175

176

177

178

179

180

Table Of Contents

Summary of GDB
- Free software
- Contributors to GDB
A Sample GDB Session
- Loading the Executable
- Setting Display width
- Setting Breakpoints
- Running the executable under GDB
- Stepping to the next line in the source program
- Stepping into a subroutine
- Examining the Stack
- Printing Variable Values
- Listing Source Code
- Setting Variable Values During a Session
Getting In and Out of GDB
- Invoking GDB
- Quitting GDB
- Shell commands
GDB Commands
- Command syntax
- Command completion
- Getting help
Running Programs Under GDB
- Compiling for debugging
- Starting your program
- Arguments To Your Program
- Program Environment
- Working directory
- Program Input and Output
- Debugging a Running Process
- Killing the child process
- Debugging programs with multiple threads
- Debugging programs with multiple processes
Stopping and Continuing
- Breakpoints
- Continuing and stepping
- Signals
- Stopping and starting multi-thread programs
Examining the Stack
- Stack frames
- Stacks Without frames
- Commands for Examining the Stack
- Backtraces
- Selecting a frame
- Information about a frame
Examining Source Files
- Printing source lines
- Searching source files
- Specifying source directories
- Source and machine code
Examining Data
- Expressions
- Program variables
- Artificial arrays
- Output formats
- Examining memory
- Automatic display
- Print settings
- Value history
- Convenience variables
- Registers
- Printing Floating Point Values
- Floating point hardware
Using GDB with Different Languages
- Switching between source languages
- Displaying the language
- Type and range checking
  - An overview of type checking
  - An overview of range checking
- Supported languages
  - C and C++
  - Fortran
Examining the Symbol Table
Altering Execution
- Assignment to variables
- Continuing at a different address
- Giving your program a signal
- Returning from a function
- Calling program functions
- Patching programs
GDB Files
- Commands to specify files
- Specifying shared library locations
- Errors reading symbol files
Specifying a Debugging Target
- Active targets
- Commands for managing targets
- Choosing target byte order
HP-UX Configuration-Specific Information
- Summary of HP Enhancements to GDB
- HP-UX dependencies
  - Linker Dependencies
  - Dependent Standard Library Routines for Run Time Checking
- Supported Platforms and Modes
- HP-UX targets
- Support for Alternate root
- Specifying object file directories
- Fix and continue debugging
  - Fix and Continue compiler dependencies
  - Fix and Continue restrictions
  - Using Fix and Continue
  - Example Fix and Continue session
- Inline Support
  - Inline Debugging in HP 9000 Systems
  - Inline Debugging in Integrity Systems
    - Debugging Inline Functions in Integrity Systems
- Debugging Macros
  - Viewing and Evaluating Macro Definitions
    - Compiler Options to Enable Macro Debugging
  - Examples for Macro Debugging
- Debugging Memory Problems
  - When to suspect a memory leak
  - Memory debugging restrictions
  - Memory Debugging Methodologies
  - Debugging Memory in Interactive Mode
    - Commands for interactive memory debugging
    - Example for interactive debugging session
  - Debugging Memory in Batch Mode
  - Debugging Memory Interactively After Attaching to a Running Process
  - Configuring memory debugging settings
  - Scenarios in memory debugging
  - Comparison of Memory Debugging Commands in Interactive Mode and Batch Mode
  - Heap Profiling
  - Memory Checking Analysis for User Defined Memory Management Routines
  - Commands to track the change in data segment value
- Thread Debugging Support
  - Support for Enabling and Disabling Specific Threads
  - Backtrace Support for Thread Debugging
  - Advanced Thread Debugging Support
  - Debugging Threads Interactively After Attaching to a Process
  - Thread Debugging in Batch Mode
    - Pre-requisites for Batch mode of Thread Debugging
    - Limitations in Batch mode of thread debugging
  - Known issues with Thread Debugging for Interactive and Batch mode
- Debugging MPI Programs
- Debugging multiple processes ( programs with fork and vfork calls)
  - Ask mode for set follow-fork-mode
  - serial mode for set follow-fork-mode
  - Support for showing unwind info
  - Printing CFM and PFS registers
- Debugging Core Files
  - Generating core files with packcore /unpackcore/getcore
  - Support for the dumpcore command
    - Enhancements to the dumpcore command
  - Support for display of run time type information
- Printing the Execution Path Entries for the Current Frame or Thread
  - Compiler Dependencies for Printing the Execution Path Entries
  - Example Illustrating Execution Path Recovery
- Invoking GDB Before a Program Aborts
- Aborting a Command Line Call
- Instruction Level Stepping
- Enhanced support for watchpoints and breakpoints
  - Deferred watchpoints
  - Hardware watchpoints
  - Hardware breakpoints
    - Setting breakpoints in unstripped shared library
  - Support for procedural breakpoints
  - Support for template breakpoints
- Debugging support for shared libraries
  - Using shared library as main program
  - Setting Deferred Breakpoints in Shared Library
  - Using catch load
  - Privately mapping shared libraries
  - Selectively Mapping Shared Libraries As Private
  - Setting breakpoints in shared library
- Language support
  - Enhanced Java Debugging Support
  - Commands for Examining Java Virtual Machine(JVM) internals
    - Java subcommands
  - Support for stack traces in Java, C, and C++ programs
  - Support for 64-bit Java, C, aC++ stack unwinding
  - Enhanced support for C++ templates
  - Support for __fpreg data type on IPF
  - Support for _Complex variables in HP C
  - Support for debugging namespaces
  - Command for evaluating the address of an expression
- Viewing Wide Character Strings
- Support for output logging
  - Support for dumping array in an ASCII file
  - Support for Fortran array slices
  - Displaying enumerators
  - Support for debugging typedefs
  - Support for steplast command for C and C++
- Getting information from a non-debug executable
- Debugging optimized code
  - Debugging Optimized Code at Various Optimization Levels
    - +O0 and +O1
    - +O2/+O3/+O4/-ipo
- Visual Interface for WDB
  - Starting and stopping Visual Interface for WDB
  - Navigating the Visual Interface for WDB display
  - Specifying foreground and background colors
  - Using the X-window graphical interface
  - Using the TUI mode
  - Changing the size of the source or debugger pane
  - Using commands to browse through source files
  - Loading source files
  - Editing source files
  - Editing the command line and command-line history
  - Saving the contents of a debugging session to a file
- Support for ddd
- Support for XDB commands
  - stop in/at dbx commands
- GNU GDB Logging Commands
- Support for command line calls in a stripped executable
  - Support for command line calls in a stripped executable on PA-RISC systems
  - Additional support for command line calls in a stripped executable
    - For 32-bit applications:
    - For 64-bit applications
  - Support for debugging stripped binaries
- Displaying the current block scope information
- Linux support
The HP-UX Terminal User Interface
- Starting the TUI
- Automatically running a program at startup
- Screen Layouts
- Cycling through the panes
- Changing pane focus
- Scrolling panes
- Changing the register display
- Changing the pane size
- Refreshing and updating the window
XDB to WDB Transition Guide
- By-function lists of XDB commands and HP WDB equivalents
- Overall breakpoint commands
- XDB data formats and HP WDB equivalents
- XDB location syntax and HP WDB equivalents
- XDB special language operators and HP WDB equivalents
- XDB special variables and HP WDB equivalents
- XDB variable identifiers and HP WDB equivalents
- Alphabetical lists of XDB commands and HP WDB equivalents
Controlling GDB
- Setting the GDB Prompt
- Setting Command Editing Options in GDB
- Setting Command History Feature in GDB
- Setting the GDB Screen Size
- Supported Number Formats
- Optional warnings and messages
- Optional messages about internal happenings
Canned Sequences of Commands
- User-defined commands
- User-defined command hooks
- Command files
- Commands for controlled output
Using GDB under gnu Emacs
GDB Annotations
- What is an annotation?
- The server prefix
- Values
- Frames
- Displays
- Annotation for GDB input
- Errors
- Information on breakpoints
- Invalidation notices
- Running the program
- Displaying source
- Annotations We Might Want in the Future
The gdb/mi Interface
- Function and purpose
- Notation and terminology
- gdb/mi Command Syntax
- gdb/mi compatibility with CLI
- gdb/mi output records
- gdb/mi command description format
- gdb/mi breakpoint table commands
- gdb/mi Data manipulation
- gdb/mi program control
- Miscellaneous GDB commands in gdb/mi
- gdb/mi Stack Manipulation Commands
- gdb/mi Symbol query commands
- gdb/mi Target Manipulation Commands
- gdb/mi thread commands
- gdb/mi tracepoint commands
- gdb/mi variable objects
Reporting Bugs in GDB
- Have you found a bug?
- How to report bugs
Installing GDB
- Compiling GDB in another directory
- Specifying names for hosts and targets
- configure options
Index

Chapter 14: HP-UX Conﬁguration-Speciﬁc Information 163

If HP WDB detects any thread error condition during the application run, the

error log is output to a ﬁle in the current working directory. The output ﬁle has

the following naming convention:

<executable name>.<pid>.threads

Where

<pid>is the process id.

14.11.5.2 Limitations in Batch mode of thread debugging

The feature does not obtain the thread-error information in batch mode for forked pro-

cess in a multiprocessing application. However, if the librtc.sl library is preloaded,

the debugger obtains the thread-error information in the batch mode for exec-ed ap-

plication.

You cannot specify an alternate output directory for the thread-error log. The thread-

error log ﬁle is output into the current working directory only.

HP WDB cannot execute both batch mode thread check and batch mode heap check

together. If the rtcconfig ﬁle has both entries, then batch heap check overrides the

batch thread check.

14.11.6 Known issues with Thread Debugging for Interactive

and Batch mode

Issue 1:

During the execution of advanced thread checking for applications that fork, in the

interactive mode, the following message appears if the GDB follows the child:

Pthread analysis file missing!

This error message appears because the thread-error information for the forked process

is not available.

However, if the forked process exec()s another binary, the thread-error information is

available for the exec -ed binary.

Issue 2:

In both interactive and batch modes, if the applications exceed their thread stack

utilization, the following error message appears:

Error accessing memory address

This occurs when GDB attempts a command line call on an already overﬂowing thread

stack.

14.12 Debugging MPI Programs

You can attach the debugger to Message Passing Interface (MPI) programs for debug-

ging. You must set the one of the following environment variables before you launch

the MPI process:

set MPI_FLAGS= egdb for invoking GDB