Appendix B. Debugging

This appendix contains information about debuggers and the debugging process.

B.1 The Solaris Modular Debugger (mdb)

The following tables list some useful commands of the Solaris Modular Debugger (mdb). For a complete list of available commands, see the Solaris Modular Debugger Guide.^[91]

Starting and Stopping mdb

Command	Description
mdb program	Starts mdb with program to debug.
mdb unix.<n> vmcore.<n>	Runs mdb on a kernel crash dump (unix.<n> and vmcore.<n> can typically be found in the directory /var/crash/<hostname>).
$q	Exits the debugger.

General Commands

Command	Description
::run arguments	Runs the program with the given arguments. If the target is currently running or it is a corefile, mdb will restart the program if possible.

Breakpoints

Command	Description
address::bp	Sets a new breakpoint at the address of the breakpoint location that is specified in the command.
$b	Lists information about existing breakpoints.
::delete number	Removes previously set breakpoints specified by their number.

Running the Debuggee

Command	Description
:s	Executes a single instruction. Will step into subfunctions.
:e	Executes a single instruction. Will not enter subfunctions.
:c	Resumes execution.

Examining Data

Command	Description
address,count format	Prints the specified number of objects (count) found at address in the specified format; example formats include B (hexadecimal, 1-byte), X (hexadecimal, 4-byte), S (string).

Information Commands

Command	Description
$r	Lists registers and their contents.
$c	Prints a backtrace of all stack frames.
address::dis	Dumps a range of memory around address as machine instructions.

Other Commands

Command	Description
::status	Prints a summary of information related to the current target.
::msgbuf	Displays the message buffer, including all console messages up to a kernel panic.