Processor Halt Identifier for Selective Software Breakpoints
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Solution Overview
Problem
Debugging digital systems with shared memory in SOC architectures is challenging due to the need for all processors to honor software breakpoints, which can lead to unnecessary halts and execution issues, especially in multiprocessor systems.
Innovation Solution
Incorporating a halt identifier field in processor instructions that allows selective halting based on a pre-selected identifier value, either within the instruction itself or in secondary memory, enabling processors to execute instructions while honoring software breakpoints only when necessary, and supporting debugging in both single and multiprocessor systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a software breakpoint is set in common shared memory, then all processors accessing that memory location must honor the breakpoint, but this causes unnecessary halts of processors that should continue executing
Solution Approach 1:
The patent applies local quality by making breakpoint identification processor-specific. Each processor has a unique identifier that is compared against identifiers stored in the halt identifier memory location. This allows the breakpoint to be honored only by the specific processor that matches the identifier, while other processors continue executing without unnecessary halts. The local quality principle transforms a global breakpoint (affecting all processors) into a localized one (affecting only the matching processor).
Solution Approach 2:
The patent introduces an intermediary mechanism - the halt identifier memory location - that mediates between the breakpoint set in shared memory and the processors. This intermediary stores processor-specific identifiers and provides a comparison mechanism that determines which processor should halt. The intermediary resolves the conflict between needing all processors to check the breakpoint (for reliability) and allowing processors to continue execution (for productivity).
2Reliability
If all processors are halted when one processor hits a breakpoint in shared memory, then no breakpoints are missed, but this causes loss of execution time and reduces debugging efficiency
Solution Approach 1:
The patent makes the halt action local rather than global by using processor-specific identifiers. When a breakpoint is hit, only the processor whose identifier matches the one stored in the halt identifier memory location is halted. Other processors continue executing, which prevents unnecessary loss of time while still ensuring that the specific processor that hit the breakpoint is properly detected and halted for debugging.
Solution Approach 2:
Instead of halting all processors (excessive action), the patent implements partial action by halting only the specific processor that matches the identifier. This partial halting is sufficient to detect and debug the breakpoint condition while avoiding the excessive time loss that would result from halting all processors unnecessarily.
3Adaptability or versatility
If software breakpoints are used in shared memory accessed by multiple processors, then memory sharing capability is utilized, but debugging becomes complex and error-prone
Solution Approach 1:
The patent introduces an intermediary structure (the halt identifier memory location with processor-specific identifiers) that simplifies the debugging of shared memory systems. This intermediary provides a clear mechanism for distinguishing which processor should halt at a breakpoint, reducing the complexity that would otherwise arise from multiple processors accessing shared memory. The intermediary acts as a dispatcher that routes the breakpoint handling to the appropriate processor.
Solution Approach 2:
The patent segments the breakpoint handling mechanism by associating different processor identifiers with different breakpoint conditions. Instead of a single global breakpoint state, the system is segmented into processor-specific breakpoint identifications. This segmentation makes the debugging system less complex by providing clear, distinct control paths for each processor rather than requiring complex coordination logic.
Data Source
AI summary
The present invention provides methods for executing instructions in a processor to facilitate the debugging of digital systems. In these methods, a halt identifier field is associated with every instruction that holds an encoding specifying an action to be performed by a processor. As instructions are executed on a processor, actions are performed by the processor based on the value of the halt identifier field of the executed instructions. In an embodiment, when each instruction is executed, the contents of the halt identifier field are compared to a pre-selected identifier value and the processor is halted if the values are the same. In a multiprocessor system, the pre-selected identifier may be a unique value that identifies the processor such that when the halt identifier field is equal to that value, the processor will halt. In a single processor system, the pre-selected value may be used to identify a task, a process, or a thread of execution that is to be halted when a halt identifier field with that value is encountered.