Linux kernel

LinuxkernelkernelsLinux-2.6.10(Linux)2.62.6 seriesfeature added to the kernelK26kernel image
The Linux kernel is a free and open-source, monolithic, Unix-like operating system kernel.wikipedia
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Linux

GNU/LinuxLinLinux operating system
The Linux family of operating systems is based on this kernel and deployed on both traditional computer systems such as personal computers and servers, usually in the form of Linux distributions, and on various embedded devices such as routers, wireless access points, PBXes, set-top boxes, FTA receivers, smart TVs, PVRs, and NAS appliances.
Linux is a family of free and open-source software operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds.

Linux distribution

distributiondistributionsLinux
The Linux family of operating systems is based on this kernel and deployed on both traditional computer systems such as personal computers and servers, usually in the form of Linux distributions, and on various embedded devices such as routers, wireless access points, PBXes, set-top boxes, FTA receivers, smart TVs, PVRs, and NAS appliances. Many desktop Linux distributions including the Linux kernel exist, but the usage share of Linux distributions is low in comparison to other operating systems.
A Linux distribution (often abbreviated as distro) is an operating system made from a software collection, which is based upon the Linux kernel and, often, a package management system.

Android (operating system)

AndroidAndroid operating systemAndroid OS
The Android operating system for tablet computers, smartphones, and smartwatches uses services provided by the Linux kernel to implement its functionality.
It is based on a modified version of the Linux kernel and other open source software, and is designed primarily for touchscreen mobile devices such as smartphones and tablets.

Linus Torvalds

Just for Fun Torvalds, LinusDavid Diamond
The Linux kernel was conceived and created in 1991 by Linus Torvalds for his personal computer and with no cross-platform intentions, but has since expanded to support a huge array of computer architectures, many more than other operating systems or kernels. This group of high-profile kernel developers, including Linus Torvalds, Greg Kroah-Hartman and Andrew Morton, commented on mass media about their objections to the GPLv3.
Linus Benedict Torvalds (born December 28, 1969) is a Finnish–American software engineer who is the creator, and historically, the principal developer of the Linux kernel, which became the kernel for many Linux distributions and operating systems such as Android and Chrome OS.

Linux kernel interfaces

interfaces of the Linux kernelkernel-to-user-space interfacekernel–user space API
The Linux kernel API, the application programming interface (API) through which user programs interact with the kernel, is meant to be very stable and to not break userspace programs (some programs, such as those with GUIs, rely on other APIs as well).
There are two types of application programming interface (API) in the Linux kernel that are not to be confused: the "kernel–user space" API and the "kernel internal" API.

Monolithic kernel

MonolithicDynamic Extendablekernel
The Linux kernel is a free and open-source, monolithic, Unix-like operating system kernel.
Modular operating systems such as OS-9 and most modern monolithic operating systems such as OpenVMS, Linux, BSD, SunOS, AIX, and MULTICS can dynamically load (and unload) executable modules at runtime.

GNU

GNU ProjectGNU operating systemThe GNU Project
Linux rapidly attracted developers and users who adopted it as the kernel for other free software projects, notably the GNU Operating System, which was created as a free, non-proprietary operating system, and based on UNIX as a by-product of the fallout of the Unix wars.
However, non-GNU kernels, such as the Linux kernel, can also be used with GNU software; as the Hurd kernel is not yet production-ready, this is how the GNU system is usually used.

GNU General Public License

GPLGNU GPLGPLv2
The Linux kernel is released under the GNU General Public License version 2 (GPLv2), with some firmware images released under various non-free licenses.
Prominent free software programs licensed under the GPL include the Linux kernel and the GNU Compiler Collection (GCC).

Linux kernel mailing list

LKMLthe mailing list
Day-to-day development discussions take place on the Linux kernel mailing list (LKML).
The Linux kernel mailing list (LKML) is the main electronic mailing list for Linux kernel development,

GNU Hurd

HurdGNU (Hurd)GNU/Hurd
At the time, the GNU Project had created many of the components required for a free operating system, but its own kernel, GNU Hurd, was incomplete and unavailable.
While the Linux kernel soon proved to be a more viable solution, development of GNU Hurd continued, albeit at a slow pace.

Linux on embedded systems

embedded Linuxembedded systems29.44%
Many consumer routers also use the Linux kernel, as well as a wide variety of other embedded devices, such as smart TVs, set-top boxes, and webcams.
Operating systems based on the Linux kernel are used in embedded systems such as consumer electronics (i.e. set-top boxes, smart TVs, personal video recorders (PVRs), in-vehicle infotainment (IVI), networking equipment (such as routers, switches, wireless access points (WAPs) or wireless routers), machine control, industrial automation, navigation equipment, spacecraft flight software, and medical instruments in general).

Greg Kroah-Hartman

This group of high-profile kernel developers, including Linus Torvalds, Greg Kroah-Hartman and Andrew Morton, commented on mass media about their objections to the GPLv3.
Greg Kroah-Hartman (GKH) is a major Linux kernel developer.

Operating system

operating systemsOScomputer operating system
The Linux kernel is a free and open-source, monolithic, Unix-like operating system kernel.
In 1991, Finnish computer science student Linus Torvalds, with cooperation from volunteers collaborating over the Internet, released the first version of the Linux kernel.

TOP500

fastest supercomputerstop 500fastest
, all of the world's 500 most powerful supercomputers run Linux.
, all the listed supercomputers (100% of the performance share) use an operating system based on the Linux kernel.

Context switch

context switchingtask switchingswitch
He started with a task switcher in Intel 80386 assembly language and a terminal driver.
For example, in the Linux kernel, context switching involves switching registers, stack pointer, and program counter, but is independent of address space switching, though in a process switch an address space switch also happens.

Alan Cox

However, the terms of the GPL state that if no version is specified, then any version may be used, and Alan Cox pointed out that very few other Linux contributors had specified a particular version of the GPL.
He maintained the 2.2 branch of the Linux kernel and continues to be heavily involved in the development of the Linux kernel, an association that dates back to 1991.

GNU Project

GNUFree System Distribution GuidelinesGNU Free System Distribution Guidelines
At the time, the GNU Project had created many of the components required for a free operating system, but its own kernel, GNU Hurd, was incomplete and unavailable.
In 1991, the Linux kernel appeared, developed outside the GNU project by Linus Torvalds, and in December 1992 it was made available under version 2 of the GNU General Public License.

Device driver

driverdriversdevice drivers
As part of the kernel's functionality, device drivers control the hardware; "mainlined" device drivers are also meant to be very stable.
In Linux environments, programmers can build device drivers as parts of the kernel, separately as loadable modules, or as user-mode drivers (for certain types of devices where kernel interfaces exist, such as for USB devices).

Free software

freefree-softwarefreely
Linux rapidly attracted developers and users who adopted it as the kernel for other free software projects, notably the GNU Operating System, which was created as a free, non-proprietary operating system, and based on UNIX as a by-product of the fallout of the Unix wars.
Some of the best-known examples include the Linux kernel, the BSD and Linux operating systems, the GNU Compiler Collection and C library; the MySQL relational database; the Apache web server; and the Sendmail mail transport agent.

Andrew Morton (computer programmer)

Andrew Morton
This group of high-profile kernel developers, including Linus Torvalds, Greg Kroah-Hartman and Andrew Morton, commented on mass media about their objections to the GPLv3.
Andrew Keith Paul Morton (born 1959) is an Australian software engineer, best known as one of the lead developers of the Linux kernel.

Linux-libre

In 2008, Free Software Foundation Latin America started Linux-libre as a project that creates a completely free variant of the Linux kernel without proprietary objects; it is used by certain completely free Linux distributions, such as those endorsed by the Free Software Foundation, while it can also be used on most distributions.
The GNU Project attempts to keep Linux-libre in synchronization with upstream development of the Linux kernel while removing any software that does not include its source code, has its source code obfuscated, or is released under proprietary licenses.

Free and open-source software

free and open-sourcefree and open source softwarefree and open source
The Linux kernel is a free and open-source, monolithic, Unix-like operating system kernel.
The Linux kernel, created by Linus Torvalds, was released as freely modifiable source code in 1991.

Kernel (operating system)

kerneloperating system kernelkernels
The Linux kernel is a free and open-source, monolithic, Unix-like operating system kernel.
As a result, the design of Linux as a monolithic kernel rather than a microkernel was the topic of a famous debate between Linus Torvalds and Andrew Tanenbaum.

Usage share of operating systems

over 90% market sharearound 90% market sharedesktop operating system market
Many desktop Linux distributions including the Linux kernel exist, but the usage share of Linux distributions is low in comparison to other operating systems.
Online usage of Linux kernel derivatives (Google systems + GNU/Linux) exceeds that of Windows.

Debian

Debian GNU/LinuxDebian ProjectDebian Linux
On 15 December 2010, the Debian Project announced that the next Debian stable version "6.0 Squeeze" would come with a kernel "stripped of all non-free firmware bits".
Debian supports Linux officially, having offered kFreeBSD for version 7 but not 8, and GNU Hurd unofficially.