ARM Cortex-R MPU Configuration: Memory Domain Isolation across ASIL-D and QM Partitions

In modern mixed-criticality ECUs, ASIL-D braking logic runs on the same silicon as Quality Management (QM) diagnostic logging. ISO 26262 requires proof of Freedom from Interference (FFI), ensuring that a bug or memory overrun in the QM code cannot corrupt ASIL-D memory space.

Microcontroller Memory Protection Units (MPU) define up to 16 hardware-enforced memory regions with strict read/write/execute permissions. When an unprivileged software component attempts to access unauthorized addresses, the MPU instantly triggers a hardware bus fault exception, isolating the thread and initiating safe state degradation.