Detecting Architectural Drift in Safety-Critical Firmware through Runtime Trace Analysis
For developers of safety-critical firmware, this work provides a practical approach to detect architectural drift, reducing manual analysis effort and supporting safety documentation.
The paper presents a methodology combining runtime trace analysis, deterministic architectural differencing, and constrained LLM-based reporting to detect architectural drift in safety-critical firmware. Evaluation on 26 test cases shows strong agreement with expert-curated references, and practitioners found the reports useful for reducing manual analysis effort.
Maintaining consistency between architectural design and runtime-observed behavior is challenging in long-lived safety-critical firmware. This paper presents a runtime-informed methodology for detecting architectural drift in ISO 26262-compliant firmware. The approach collects hardware-assisted execution traces, abstracts them into message exchanges among firmware components, and compares the resulting runtime behavior with design-time sequence diagrams through a deterministic differencing step. The computed delta identifies discrepancies as confirmed, missing, additional, or inverted, while a constrained LLM-based step generates a human-readable report only to support expert review. We evaluate the methodology in an industrial firmware context through agreement-based validation and a practitioner survey. Results over 26 test cases show strong agreement between the generated deltas and expert-curated references, while practitioners perceive the reports as useful for interpreting drift, reducing manual analysis effort, and supporting safety-oriented documentation activities. The findings suggest that combining runtime trace analysis, deterministic architectural differencing, and constrained LLM-based reporting can practically support architectural drift detection in evolving safety-critical firmware.