New paper proposes hybrid HAL for Software Defined Vehicles to boost modularity

The shift to Software Defined Vehicles (SDVs) demands modular, interoperable architectures with real-time processing and over-the-air (OTA) update capabilities. However, current automotive systems rely on tightly coupled software and hardware, making it difficult to meet these requirements. A critical enabler is a robust Hardware Abstraction Layer (HAL) that decouples software from hardware. This paper, published at the 2025 IEEE IAVVC conference, systematically evaluates existing automotive HALs and explores mechanisms from non-automotive domains — smartphones, networking, and industrial automation — to extract cross-domain lessons. A criteria-driven framework assesses each HAL against SDV-specific needs like safety, portability, and hardware efficiency.

The findings reveal that middleware-based HALs offer portability and modularity, but hypervisor-based approaches better support safety, OTA readiness, and hardware efficiency. Both approaches have limitations, prompting a recommendation for a hybrid HAL design that integrates hypervisor isolation with middleware standardization. The research provides actionable guidance for building flexible, scalable HALs that support SDVs across their lifecycle. This work contributes to ongoing automotive software architecture developments, helping engineers design systems that can evolve through software updates without hardware changes.