The Heinsenburg Debugging Technology

Future Directions

Cygnus currently has a highly portable and configurable version of the target collection agent. It can be built with or without certain components (such as the expression evaluator) in order to fit in a small memory footprint. The maximum size of the trace buffer is also configurable.

The current implementation of the expression evaluator is limited to expressions without side effects. Adding operators with side effects would not be at all difficult. A somewhat more ambitious enhancement would be adding function calls to the expression language. With both side-effect operators and function calls, you would have a fairly extensive ability to patch your program and modify its behavior on the fly.

Since we do have the expression evaluator on the target, it would be possible to attach a condition expression to each tracepoint, such that data would be collected only if the condition were true. The same might be done for breakpoints, making conditional breakpoints much faster (since the condition would no longer have to be evaluated by the debugger.)

Finally, the current portable implementation requires that the target program be stopped at a breakpoint before GDB can query the trace buffer. A very powerful enhancement would be to allow GDB to read from the trace buffer even when the target is running.