Processor Breakpoint Bit Debugging Mechanism
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Solution Overview
Problem
Debugging software in computing systems can be challenging due to the limited number of debug registers, making it difficult to efficiently identify and address errors in executable code.
Innovation Solution
The system implements breakpoint bits associated with each instruction, allowing the processor to report an error when a breakpoint bit is set, enabling efficient debugging by allowing breakpoints to be set for an arbitrary number of instructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional debug registers are used for debugging, then the debugging mechanism is simple to implement, but the number of breakpoints that can be set is limited
Solution Approach 1:
The patent segments the debugging mechanism by separating breakpoint registration from instruction execution. Breakpoints are registered in a breakpoint table independently, and the processor checks this table during instruction fetch rather than using traditional debug registers. This segmentation allows multiple breakpoints to be set without increasing the number of hardware debug registers.
Solution Approach 2:
The patent introduces a breakpoint table as an intermediary data structure between the debugger and the processor execution unit. This table stores breakpoint addresses and enables the processor to check for breakpoints during normal instruction fetch operations without requiring dedicated debug registers for each breakpoint.
2Adaptability or versatility
If breakpoint bits are stored in a separate memory location, then any number of breakpoints can be set, but the access time for breakpoint checking increases
Solution Approach 1:
The patent merges the breakpoint table storage with the instruction cache memory structure. Both instructions and breakpoint bits are stored in the same L1 instruction cache, allowing the processor to fetch both the instruction and its corresponding breakpoint bit in a single memory access operation, thus eliminating additional access time overhead.
Solution Approach 2:
The patent positions breakpoint bits at the same memory hierarchy level as instructions (L1 instruction cache), ensuring that both have equal access speed characteristics. This eliminates the performance penalty that would result from storing breakpoint information in slower, separate memory locations.
3Speed
If breakpoint bits are integrated with instructions in the same cache, then memory access efficiency improves, but the cache capacity for instructions decreases
Solution Approach 1:
The patent segments the cache capacity by allocating only one bit per instruction for breakpoint storage, rather than storing full breakpoint information. This minimal segmentation approach preserves the majority of cache capacity for instructions while still enabling breakpoint functionality.
Solution Approach 2:
The patent applies local quality by storing breakpoint information only where needed (in the instruction cache alongside relevant instructions) rather than duplicating breakpoint data structures throughout the system. Each instruction location has its breakpoint bit stored locally in the same cache line, optimizing both space and access efficiency.
Data Source
AI summary
A system and method for debugging in hardware. In some embodiments, the system includes a processor, the processor including: a first memory configured to store an instruction; and a second memory configured to store a breakpoint bit, for the instruction, the processor being configured to: determine that the breakpoint bit is set, and based on determining that the breakpoint bit is set, to report an error.