Method and apparatus for debugging a data processing system

A data processing system, comprising:

• a central processing unit coupled to a bus;
• and
• a debug circuit, comprising:
• a first breakpoint unit, coupled to the bus, for detecting a breakpoint event and providing a first output in response to detecting the breakpoint event;
• and
• a first plurality of serially-connected breakpoint units for receiving the first output at a front end of the serially-connected breakpoints and providing a final output in response to the first output at a back end of the serially-connected breakpoints, wherein the final output is for identifying an action.

A debug circuit, comprising:

• first breakpoint means for detecting a breakpoint event and providing a first output in response to detecting the breakpoint event, wherein the first output is a trigger;
• second breakpoint means, coupled to the first breakpoint means, for providing a second output in response to the first output, wherein the second output is an action;
• third breakpoint means, coupled to the first breakpoint means, for providing a third output in response to the first output;
• and
• a fourth breakpoint means, coupled to the third breakpoint means, for providing a fourth output in response to the second output.

A method of debugging with respect to a breakpoint event, comprising:

• detecting the breakpoint event;
• generating a first action in response to the breakpoint event;
• generating a second action in response to the breakpoint event;
• and
• comparing results of the first action and the second action.