Toward a Taxonomy of Virtualization for Microcontroller-Based Mixed-Criticality Systems

Safety-critical embedded systems are shifting from federated architectures, where each function runs on a dedicated processing unit, toward integrated architectures that consolidate mixed-criticality functions on a shared platform. This consolidation increasingly involves systems based on microcontrollers (MCU), which host hard real-time functions and differ from application processors in their limited privilege levels, absence of a Memory Management Unit (MMU), reliance on a Memory Protection Unit (MPU), and constrained resources. Existing surveys and taxonomies are anchored to application processors and do not systematically address these MCU-specific constraints. This paper proposes a taxonomy of virtualization for MCU-based mixed-criticality systems (MCS) along four orthogonal dimensions: virtualization layer, execution environment, interface exposed to guests, and guest execution model.