A memory protection unit (MPU), is a computer hardware unit that provides
memory protection
Memory protection is a way to control memory access rights on a computer, and is a part of most modern instruction set architectures and operating systems. The main purpose of memory protection is to prevent a process from accessing memory that ha ...
. It is usually implemented as part of the
central processing unit
A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, an ...
(CPU). MPU is a trimmed down version of
memory management unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ad ...
(MMU) providing only
memory protection
Memory protection is a way to control memory access rights on a computer, and is a part of most modern instruction set architectures and operating systems. The main purpose of memory protection is to prevent a process from accessing memory that ha ...
support. It is usually implemented in low power processors that require only
memory protection
Memory protection is a way to control memory access rights on a computer, and is a part of most modern instruction set architectures and operating systems. The main purpose of memory protection is to prevent a process from accessing memory that ha ...
and do not need the full fledged feature of a
memory management unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ad ...
like
virtual memory
In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...
management.
Overview
The MPU allows the
privileged software to define memory regions and assign memory access permission and memory attributes to each of them. Depending on the implementation of the
processor
Processor may refer to:
Computing Hardware
* Processor (computing)
**Central processing unit (CPU), the hardware within a computer that executes a program
*** Microprocessor, a central processing unit contained on a single integrated circuit (I ...
, the number of supported memory regions will vary. The MPU on
ARMv8-M processors supports up to 16 regions. The memory attributes define the ordering and merging behaviors of these regions, as well as
caching and buffering attributes. Cache attributes can be used by internal caches, if available, and can be exported for use by system caches.
MPU monitors transactions, including
instruction fetches and data accesses from the
processor
Processor may refer to:
Computing Hardware
* Processor (computing)
**Central processing unit (CPU), the hardware within a computer that executes a program
*** Microprocessor, a central processing unit contained on a single integrated circuit (I ...
, which can trigger a
fault exception when an access violation is detected. The main purpose of memory protection is to prevent a
process
A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic.
Things called a process include:
Business and management
*Business process, activities that produce a specific se ...
from accessing memory that has not been allocated to it. This prevents a
bug or
malware
Malware (a portmanteau for ''malicious software'') is any software intentionally designed to cause disruption to a computer, server, client, or computer network, leak private information, gain unauthorized access to information or systems, depri ...
within a process from affecting other processes, or the
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
itself.
See also
*
Memory management unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ad ...
*
Memory protection
Memory protection is a way to control memory access rights on a computer, and is a part of most modern instruction set architectures and operating systems. The main purpose of memory protection is to prevent a process from accessing memory that ha ...
References
{{Memory management navbox
Central processing unit
Digital circuits
Memory management