Processor Debug Clock Mechanism for Error Cascade Prevention
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Solution Overview
Problem
Complex hardware systems face challenges in debugging hardware failures due to unpredictable behavior and cascades of interdependent error indications, making it difficult to determine the root cause of failures, especially when errors are masked by redundant or misleading information.
Innovation Solution
The system includes a processing block with a debug clock that remains operational, allowing for continued data access and error handling by disabling the functional clock upon error detection, thereby preventing cascades of errors and providing relevant error information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the processing block continues operating after error detection, then data access and processing can continue, but cascades of interdependent error indications occur making root cause identification difficult
Solution Approach 1:
The patent separates the processing block into two independent clock domains: a functional clock that can be halted on error, and a debug clock that continues independently. This segmentation allows the debug infrastructure to operate autonomously from the functional processing, enabling continuous data access while preventing error cascades in the functional block.
Solution Approach 2:
The patent introduces a debug clock as an intermediary timing source that mediates between the functional processing block and the debug infrastructure. This intermediary allows the debug block to access data and state information independently of the functional clock, providing a clear view of the system state at error occurrence without being affected by functional block operations.
2Loss of information
If multiple error indications are reported in parallel, then comprehensive error information is provided, but redundant or misleading information confuses debugging
Solution Approach 1:
The patent extracts the debug infrastructure into a separate clock domain with its own debug clock. This extraction allows the debug block to capture and report error information independently, providing comprehensive error data without the interference of functional block operations that generate cascading errors. The debug block can report the actual error state without being contaminated by subsequent functional block failures.
3Reliability
If the functional clock is disabled upon error detection, then error cascades are prevented, but data access may be interrupted
Solution Approach 1:
The patent segments the clocking system into functional clock and debug clock domains. When an error occurs, only the functional clock is disabled to prevent error cascades, while the debug clock continues independently to maintain data access and allow the debug block to capture complete error information without interruption.
4Ease of operation
If a separate debug clock is introduced, then continuous data access is maintained during errors, but device complexity increases
Solution Approach 1:
The debug clock serves multiple functions: it clocks the debug block for error detection, maintains data access continuity, enables state capture at error occurrence, and provides a timing reference for the debug infrastructure. This multi-functionality justifies the added complexity by consolidating multiple debug requirements into a single timing source.
Data Source
AI summary
An error-handling processing circuit and system are provided. The system can receive an error signal, such as an interrupt, and decouple (e.g., by a gate signal) a functional clock from a processing block, in some instances effectively halting the processing block's operation. This can prevent a cascade of interdependent errors, thereby avoiding producing redundant or confusing error information. The system can include the processing block, a debug clock not coupled to the processing block, and a data block (e.g., a register file) coupled to the debug clock and to an external input/output interface. The data block can be configured to continue receiving a clock signal via a multiplexer from the debug clock without disruption after the functional clock is decoupled, enabling the data block to remain operational for debugging.