Synchronous Microprocessor Clock Stop Mechanism for Debugging
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Solution Overview
Problem
Existing debugging methods for microprocessors are limited as they can only stop the internal clock asynchronously, making it difficult to precisely identify the cause of unintended results, as the preserved state may not accurately reflect the execution point of the problematic instruction.
Innovation Solution
Inserting a stop instruction into the instruction sequence allows the internal clock to be synchronized with instruction execution, enabling precise control over when the clock generation ceases, thereby preserving the microprocessor state for easier debugging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stop signal is transmitted using a clock stop mechanism to preserve the microprocessor state, then the state is preserved contemporaneously with the receipt of the stop signal, but the preserved state may be long after the execution of the instruction that caused the problem, requiring educated guesses for debugging
Solution Approach 1:
The patent applies preliminary action by inserting a stop instruction into the instruction sequence before the problematic instruction executes. This stop instruction preemptively halts the clock signal generation at a known point in time, ensuring that when the state is preserved, it corresponds to a specific, identifiable instruction execution point rather than an unknown later state. This allows debuggers to capture the microprocessor state at the exact moment before the bug manifests.
2Measurement precision
If event logic is designed to detect a particular event and generate a stop signal, then the state is preserved contemporaneous with the occurrence of the event, but the particular event is typically not indicative of the problem causing the bug since the designer is aware that such problems may occur
Solution Approach 1:
The patent applies universality by making the stop instruction a general-purpose debugging tool that can be inserted at any location in the instruction sequence, rather than relying on specific event logic designed for particular known events. The stop instruction serves multiple debugging scenarios by allowing users to halt execution at any desired point, making it adaptable to unknown or unexpected bugs that event logic specifically designed for known events would miss.
3Ease of operation
If the internal clock is stopped asynchronously to instruction execution, then the clock generation can be ceased, but it is difficult to precisely identify the cause of unintended results as the preserved state may not accurately reflect the execution point
Solution Approach 1:
The patent merges the clock control function with the instruction execution flow by embedding a stop instruction within the normal instruction sequence. This integration ensures that the clock halt action is synchronized with instruction execution - when the stop instruction is decoded and executed, the clock signal is halted at that precise moment. This combination of clock control and instruction flow allows the preserved state to accurately reflect the execution point, eliminating the ambiguity of asynchronous halting.
Data Source
AI summary
A method and apparatus for stopping the internal clock of a microprocessor synchronously with the execution of an instruction is provided. A stop instruction is placed in a sequence of instructions to be executed by the microprocessor. The execution of the stop execution may store a stop value into a stop register of the microprocessor. Clock stop logic detects when the stop value has been stored into the stop register. The clock stop logic instructs a clock generation component, of the microprocessor, to cease generation of an internal clock signal, thereby preventing the microprocessor from changing state. As further instructions are not executed by the microprocessor, the state of the microprocessor reflects the execution of the instruction immediately prior to the stop instruction. The processing state of the microprocessor may be obtained for use in debugging the design of the microprocessor or the instructions executed thereby.