Editing Microkernel (section)

{{Short description|Kernel that provides fewer services than a traditional kernel}}
{{Use dmy dates|date=February 2021}}
[[File:OS-structure.svg|thumb|450px|Structure of monolithic and microkernel-based operating systems, respectively]]

In [[computer science]], a '''microkernel''' (often abbreviated as '''μ-kernel''') is the near-minimum amount of [[software]] that can provide the mechanisms needed to implement an [[operating system]] (OS). These mechanisms include low-level [[address space]] management, [[thread (computing)|thread]] management, and [[inter-process communication]] (IPC).

If the hardware provides multiple [[Protection ring|rings]] or [[CPU modes]], the microkernel may be the only software executing at the most privileged level, which is generally referred to as [[kernel mode|supervisor or kernel mode]]. Traditional operating system functions, such as [[device driver]]s, [[protocol stack]]s and [[file system]]s, are typically removed from the microkernel itself and are instead run in [[user space]].<ref>{{cite web
 | url = http://www.minix3.org/theses/herder-true-microkernel.pdf
 | title = Toward a True Microkernel Operating System
 | date = 23 February 2005 | access-date = 22 June 2015
 | first = Jorrit N. | last=Herder | website = minix3.org
}}</ref>

In terms of the source code size, microkernels are often smaller than [[monolithic kernel]]s. The [[MINIX&nbsp;3]] microkernel, for example, has only approximately 12,000 lines of code.<ref>{{cite web|url=http://wiki.minix3.org/doku.php?id=www:documentation:read-more|title=read-more|access-date=20 December 2016}}</ref>