MPU

MPU stands for Memory Protection Unit, a hardware component used in many microcontrollers and processors to enforce memory access permissions on defined regions. It provides isolation, security, and safety by restricting how code can read, write, or execute memory. Unlike a full MMU, MPUs typically do not implement virtual memory.

An MPU defines several regions, each with a base address, a size, and attributes that specify read, write, and execute permissions, as well as privileged vs unprivileged access. Regions can often be enabled/disabled individually and subdivided into subregions. Access checks occur on every memory access, and violations trigger a fault.

In ARM Cortex-M devices, the MPU commonly supports up to eight regions (device-dependent) and uses registers such as RBAR, RASR to configure them. It is often programmed by an operating system during context switches to enforce task isolation.

Compared with MMUs, MPUs are simpler and faster, but do not provide virtual addressing or paging. They are well-suited for embedded and safety-critical systems where deterministic memory protection is more important than full virtual memory.

Applications include automotive, aerospace, consumer electronics, and other environments requiring protection of critical code and data from bugs or compromised software.

Other meanings: MPU may refer to microprocessor unit or multi-processor unit in different domains; in embedded systems, Memory Protection Unit is the primary interpretation.