b

The b command sets and displays breakpoints.

Format

The format for the b command is:

b

b adr..

b adr -s str

where:

adr	specifies an address for the breakpoint. Up to 32 breakpoints addresses can be set.
-s str	executes the command string when the breakpoint is hit.

Invoking the b command with no options causes the Monitor to print a list of the current breakpoints.

Functional Description

The b command sets a breakpoint at the specified address or addresses. Multiple addresses may be specified. Specified addresses must be word-aligned.

 

The Monitor automatically assigns a number to each breakpoint.
The Monitor allocates the lowest available breakpoint number from 0 to 31 to any new breakpoint.

The Monitor reports a new breakpoint's number immediately after the breakpoint is set (see the examples at the end of this subsection for illustration of this). The assigned numbers can be used in the db (Delete Breakpoint) command.

The brkcmd Variable

When a breakpoint is reached, the command list specified in the environment variable brkcmd is executed. The default setting for brkcmd is:

brkcmd = "l @pc 1"

This command "l @pc 1", specifies that when the breakpoint occurs, the Monitor will disassemble one line starting at the address of the program counter.

You can change the breakpoint command variable with the set command. For example, you can include additional monitor commands in the brkcmd variable. You must separate additional commands on the command line with a semicolon. For example, entering the following command lists one line after reaching a breakpoint, and then displays all the register values.

set brkcmd "l @epc 1;r *"

By default, breakpoints are cleared when the load command is executed. See the section on the load command later in this document for details on how to override automatic breakpoint clearing after a download operation.

Some examples illustrating the use of the b command follow.
 

PMON> b a002000c	Set a breakpoint at 0xa002000c.
Bpt 1 = a002000c
PMON> b  Bpt 0 = 8002022c Bpt 1 = a002000c	Display all breakpoints.
PMON> b 80021248 -s "r"	Set a breakpoint at 0x80021248. Display registers when the breakpoint is encountered.

See Also

db and load commands.

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