[Paper] Relevant HAL Interface Requirements for Embedded Systems

Source: arXiv - 2512.14514v1

Overview

Embedded software often talks to hardware through a Hardware Abstraction Layer (HAL). When the HAL is mis‑used, the hardware can behave unpredictably, causing costly system crashes or even physical damage. This paper formalises what HAL requirements are truly critical for avoiding such failures and shows how model‑checking can automatically prove their relevance, using real‑world SPI‑bus bug reports as a testbed.

Key Contributions

• Formal definition of “relevance” for HAL interface requirements, grounded in safety‑critical failure prevention.
• Model‑checking‑based proof technique that can certify a requirement as indisputably relevant.
• Automated extraction pipeline that turns issue‑report data (e.g., bug tickets) into candidate HAL requirements.
• Case‑study validation on three real SPI‑bus bugs involving the Linux spidev HAL, demonstrating feasibility.
• Roadmap for a new prioritisation paradigm that focuses on preventing hardware‑induced failures rather than generic defect triage.

Methodology

1. Requirement Modelling – The authors encode HAL API contracts (pre‑/post‑conditions, usage patterns) as logical specifications.
2. Failure Scenario Extraction – From issue reports they identify the concrete sequence of API calls that led to a hardware fault.
3. Relevance Formalisation – A requirement is relevant if, assuming it holds, the failure scenario becomes unreachable in the system model.
4. Software Model Checking – Using a symbolic model checker (e.g., CBMC or CPAchecker), they automatically explore all possible program paths. The checker tries to find a counterexample where the failure occurs without violating the candidate requirement. If none exists, the requirement is proved relevant.
5. Iterative Pruning – By repeating the process for each candidate, they obtain a minimal set of provably relevant requirements.

The pipeline is deliberately lightweight: it works on existing source code and bug reports, requiring only modest annotation effort.

Results & Findings

• For each of the three SPI‑bus bugs, the approach identified one or two HAL requirements (e.g., “the SPI clock must be configured before any transfer”) that, when enforced, mathematically guarantee the observed failure cannot happen.
• The model‑checking step completed within seconds to a few minutes per requirement on a commodity laptop, showing that the technique scales to small‑to‑medium embedded code bases.
• The extracted relevant requirements aligned with the developers’ intuition, confirming that the formal notion of relevance matches practical safety concerns.

Practical Implications

• Prioritised Testing & Code Review – Teams can focus QA resources on the handful of HAL contracts that matter most for hardware safety, rather than scattering effort across all API documentation.
• Automated Guard Generation – Once a requirement is proved relevant, developers can auto‑generate runtime assertions or static analysis rules that enforce it, catching misuse early in CI pipelines.
• Regulatory Compliance – Safety‑critical domains (automotive, aerospace, medical devices) often need evidence that critical interfaces are correctly used; a formal relevance proof provides a concrete artifact for audits.
• Issue‑Report Mining – The extraction step shows that existing bug trackers can be repurposed to drive safety‑oriented requirement engineering, reducing the need for separate specification documents.

Limitations & Future Work

• Scalability – The current evaluation is limited to small SPI examples; larger HALs with dozens of APIs may cause state‑space explosion in model checking.
• Annotation Overhead – Accurate pre/post‑conditions must be supplied manually, which can be error‑prone for legacy code.
• Dynamic Hardware Effects – The model abstracts away timing‑related faults (e.g., bus contention) that might also be safety‑critical.

Future research directions include integrating the approach with symbolic execution to handle larger code bases, extending the relevance notion to timing and concurrency constraints, and building tooling that automatically extracts and annotates HAL contracts from source repositories.

Authors

• Manuel Bentele
• Andreas Podelski
• Axel Sikora
• Bernd Westphal

Paper Information

• arXiv ID: 2512.14514v1
• Categories: cs.LO, cs.SE
• Published: December 16, 2025
• PDF: Download PDF