You can set breakpoints in your program by selecting the boxed line numbers in the Source Code pane of a Process window. A boxed line number indicates that the line generates executable code. A icon masking a line number indicates that a breakpoint is set on the line. Selecting the icon clears the breakpoint.
When a program reaches a breakpoint, it stops. You can let the program resume execution in any of the following ways:
• Use the set program counter command to resume program execution at a specific source line, machine instruction, or absolute hexadecimal value. See "Setting the Program Counter".
• Set conditional breakpoints that cause a program to stop after it evaluates a condition that you define, for example, “stop when a value is less than eight." See "Setting Eval Points".
TotalView provides additional features for working with breakpoints, process barrier breakpoints, and eval points. For more information, see Chapter 8, "Setting Action Points".
icon masking a line number indicates that a breakpoint is set on the line. Selecting the 
icon clears the breakpoint.