To set a machine-level breakpoint, you must first display assembler code. (For information, see
“Viewing the Assembler Version of Your Code”.) You can now select an instruction. TotalView replaces some line numbers with a dotted box (

)—this indicates the line is the beginning of a machine instruction. If a line has a line number, this is the line number that appears in the Source Pane. Since instruction sets on some platforms support variable-length instructions, you might see a different number of lines associated with a single line contained in the dotted box. The

icon appears, indicating that the breakpoint occurs before the instruction executes.
If you set a breakpoint on the first instruction after a source statement, however, TotalView assumes that you are creating a source-level breakpoint, not an assembler-level breakpoint.
If you set machine-level breakpoints on one or more instructions generated from a single source line, and then display source code in the Source Pane, TotalView displays an

icon (
Figure 222) on the line number. To see the actual breakpoint, you must redisplay assembler instructions.