Address-Qualified Debug Instruction Suppression in Processors
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Solution Overview
Problem
The removal of debug instructions from software applications can alter execution characteristics, particularly in real-time systems, leading to undesired exceptions and changes in code image, branch targets, and page boundaries.
Innovation Solution
A processor implementation that supports selective execution semantics for debug instructions based on their memory addresses, using memory page attributes and segment or region markings to suppress or enable debug operations without altering the code image, allowing certain instances to operate with debug or NOP semantics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If debug instructions are removed from software applications, then execution characteristics are altered and undesired exceptions occur, but debug operations cannot be performed during production
Solution Approach 1:
The patent implements dynamic control of debug instruction execution through runtime condition codes and address qualification mechanisms. The system transitions debug instructions from static removal to dynamic suppression/enabling based on execution context, allowing the same instruction to behave differently at runtime depending on whether debug mode is active for that specific address range.
Solution Approach 2:
The patent applies local quality by enabling debug functionality selectively at specific memory addresses rather than globally. Through address-qualified conditional debug instructions, only instructions within designated debug regions are suppressed or enabled, while the rest of the code executes normally. This localized approach preserves execution characteristics in production code while maintaining debug capability where needed.
2Ease of operation
If debug instructions are kept in production code, then debug operations are available, but undesired exceptions and changes in code image occur
Solution Approach 1:
The patent segments the code image into distinct regions with different execution semantics. By dividing the address space into debug-qualified regions and normal regions, the system can apply different execution rules to different segments. Debug instructions in marked regions are suppressed during production execution, while instructions in normal regions execute as intended, preventing undesired exceptions.
Solution Approach 2:
The patent changes the execution parameter of debug instructions from their default debug semantics to NOP (no operation) semantics through address qualification and condition code evaluation. This parameter transformation allows the same instruction binary to serve dual purposes: debug operations when enabled, and harmless no-ops when suppressed, eliminating undesired exceptions while preserving code integrity.
3Reliability
If debug instructions are suppressed without altering code image, then execution characteristics are maintained, but mechanism complexity increases
Solution Approach 1:
The patent introduces intermediary components including condition code registers, address qualification logic, and memory management unit extensions that mediate between the fetched instruction and its execution. These intermediaries evaluate address ranges and condition codes to determine whether to suppress debug instructions, providing a systematic yet relatively simple mechanism that maintains execution characteristics without requiring complex code transformation.
Data Source
AI summary
A processor implementation supports selection of an execution mode for debug instruction instances based on respective addresses thereof in addressable memory can provide an attractive mechanism for executing debug instructions in a way that allows some instances of the instructions to operate with debug semantics while suppressing other instances by executing them with no-operation (NOP) semantics. In some embodiments, selection of operative execution semantics may be based on attributes of a memory page in which a particular debug instruction instance resides. In some embodiments, portions of an address space may be delimited (e.g., using values stored in bounding registers and addresses of particular debug instruction instances compared against the delimited portions to select appropriate execution semantics. In some embodiments, both types of evaluations may be used in selecting appropriate execution semantics for a particular debug instruction instance.