Instruction Replacement Register for Software Breakpoint Debugging
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Solution Overview
Problem
Software breakpoints in conventional processor-based systems are limited by their inability to execute certain instructions in debug mode, require frequent reprogramming of non-volatile memory, and are resource-intensive, making them unsuitable for interactive debugging in systems with embedded Flash memory.
Innovation Solution
A processing system that includes a processor configured to switch between debug and non-debug modes using a software breakpoint, with an instruction replacement register to store and retrieve replaced instructions, allowing the processor to fetch instructions from either program memory or the replacement register, and a control component to manage this process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If software breakpoints are used in conventional processor-based systems, then breakpoints can be inserted without additional hardware modules, but the system requires frequent reprogramming of non-volatile memory which is time-consuming and limited in durability
Solution Approach 1:
The patent segments the instruction storage into two separate components: program memory for storing original program instructions and an instruction replacement register for storing replaced instructions. This segmentation allows the system to switch between debugging and normal operation without reprogramming the entire program memory, thereby reducing the time loss associated with frequent memory reprogramming while maintaining the ease of breakpoint insertion.
2Adaptability or versatility
If software breakpoints replace instructions in program memory, then breakpoints can be inserted, but certain instructions cannot be executed correctly in debug mode and the program memory must be reprogrammed to restore original instructions
Solution Approach 1:
The patent extracts the replaced instructions from program memory and stores them in a separate instruction replacement register. This extraction allows the original program memory contents to remain unchanged, ensuring that instructions can be executed correctly in both debug and non-debug modes. The instruction replacement register serves as a temporary storage that preserves the original instructions without requiring reprogramming of the program memory.
3Productivity
If hardware breakpoint modules are added to supplement software breakpoints, then more breakpoints can be inserted simultaneously, but the silicon area cost increases significantly
Solution Approach 1:
The patent creates a universal instruction replacement mechanism that can serve multiple breakpoint locations without requiring separate hardware modules for each breakpoint. The single instruction replacement register can store instructions replaced at any breakpoint location, allowing multiple breakpoints to be inserted simultaneously using the same hardware structure. This multi-functional approach increases the number of simultaneous breakpoints while avoiding the silicon area cost of multiple dedicated hardware breakpoint modules.
Data Source
AI summary
Methods and systems are provided for debugging a program executing on a processor. In a first implementation, a processing system includes a processor configured for switching to a debug mode from a non-debug mode upon executing a software breakpoint. The system may include a program memory configured to hold instructions for a program, where the software breakpoint replaces at least one of the instructions. The system may also include an instruction replacement register separate from the program memory that is configured to receive the replaced instruction from any of the processor and an external debugger. The system may further include a control component that controls whether the processor fetches a next instruction for execution from the program memory or from the instruction replacement register.