A memory protection unit (MPU) is a
computer hardware
Computer hardware includes the physical parts of a computer, such as the central processing unit (CPU), random-access memory (RAM), motherboard, computer data storage, graphics card, sound card, and computer case. It includes external devices ...
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 h ...
. 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 primary Processor (computing), processor in a given computer. Its electronic circuitry executes Instruction (computing), instructions ...
(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 that examines all references to computer memory, memory, and translates the memory addresses being referenced, known as virtual mem ...
(MMU) providing only memory protection support. It is usually implemented in low power processors that require only memory protection and do not need the full-fledged feature of a MMU 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 ver ...
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, 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, 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 s ...
from accessing memory that has not been allocated to it. This prevents a
bug or
malware
Malware (a portmanteau of ''malicious software'')Tahir, R. (2018)A study on malware and malware detection techniques . ''International Journal of Education and Management Engineering'', ''8''(2), 20. is any software intentionally designed to caus ...
within a process from affecting other processes, or the
operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
itself.
See also
*
Memory management unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit that examines all references to computer memory, memory, and translates the memory addresses being referenced, known as virtual mem ...
*
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 h ...
References
{{Memory management navbox
Central processing unit
Digital circuits
Memory management