Kernel that provides fewer services than a traditional kernel

Microkernel

Microkernel

In <a href="/en/Computer_science" title="Computer science" class="wl">computer science</a>, a microkernel (often abbreviated as μ-kernel) is the near-minimum amount of <a href="/en/Software" title="Software" class="wl">software</a> that can provide the mechanisms needed to implement an <a href="/en/Operating_system" title="Operating system" class="wl">operating system</a> (OS). These mechanisms include low-level <a href="/en/Address_space" title="Address space" class="wl">address space</a> management, <a href="/en/Thread_(computing)" title="Thread (computing)" class="wl">thread</a> management, and <a href="/en/Inter-process_communication" title="Inter-process communication" class="wl">inter-process communication</a> (IPC).

<div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">Kernel that provides fewer services than a traditional kernel</div>

<figure class="wiki-thumb"><a href="/en/File:OS-structure.svg" class="mw-file-description image media-thumb" data-hash="File:OS-structure.svg"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/67/OS-structure.svg/450px-OS-structure.svg.png" decoding="async" data-file-width="750" data-file-height="400" data-file-type="drawing" height="240" width="450" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/67/OS-structure.svg/675px-OS-structure.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/67/OS-structure.svg/900px-OS-structure.svg.png 2x" alt="OS-structure.svg"></a><figcaption>Structure of monolithic and microkernel-based operating systems, respectively</figcaption></figure>

If the hardware provides multiple <a href="/en/Protection_ring" title="Protection ring" class="wl">rings</a> or <a href="/en/CPU_modes" title="CPU modes" class="wl">CPU modes</a>, the microkernel may be the only software executing at the most privileged level, which is generally referred to as <a href="/en/Kernel_mode" title="Kernel mode" class="mw-redirect wl">supervisor or kernel mode</a>. Traditional operating system functions, such as <a href="/en/Device_driver" title="Device driver" class="wl">device drivers</a>, <a href="/en/Protocol_stack" title="Protocol stack" class="wl">protocol stacks</a> and <a href="/en/File_system" title="File system" class="wl">file systems</a>, are typically removed from the microkernel itself and are instead run in <a href="/en/User_space" title="User space" class="mw-redirect wl">user space</a>.<a href="#cite_note-1" style="counter-reset: mw-Ref 1;">[1]</a>

In terms of the source code size, microkernels are often smaller than <a href="/en/Monolithic_kernel" title="Monolithic kernel" class="wl">monolithic kernels</a>. The <a href="/en/MINIX_3" title="MINIX 3" class="mw-redirect wl">MINIX&nbsp;3</a> microkernel, for example, has only approximately 12,000 lines of code.<a href="#cite_note-2" style="counter-reset: mw-Ref 2;">[2]</a>

In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system . These mechanisms include low-level address space management, thread management, and inter-process communication . If the hardware provides multiple rings or CPU modes, the microkernel may be the only software executing at the most privileged level, which is generally referred to as supervisor or kernel mode. Traditional operating system functions, such as device drivers, protocol stacks and file systems, are typically removed from the microkernel itself and are instead run in user space. In terms of the source code size, microkernels are often smaller than monolithic kernels. The MINIX 3 microkernel, for example, has only approximately 12,000 lines of code. 