Operating systems based on the

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ...

are used in

embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' ...

s such as

consumer electronics Consumer electronics or home electronics are Electronics, electronic (Analogue electronics, analog or digital electronics, digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for ...

(eg.

set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of si ...

es,

smart TV A smart TV, also known as a connected TV (CTV), is a traditional television set with integrated Internet and interactive Web 2.0 features, which allows users to stream music and videos, browse the internet, and view photos. Smart TVs are a techn ...

s and personal video recorders (PVRs)), in-vehicle infotainment (IVI),

networking Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...

equipment (such as routers,

switches In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type ...

wireless access point In computer networking, a wireless access point (WAP), or more generally just access point (AP), is a networking hardware device that allows other Wi-Fi devices to connect to a wired network. As a standalone device, the AP may have a wired co ...

s (WAPs) or

wireless router A wireless router is a device that performs the functions of a router and also includes the functions of a wireless access point. It is used to provide access to the Internet or a private computer network. Depending on the manufacturer and mod ...

s),

machine control In civil engineering, machine control is used to accurately position earthwork machinery based on 3D design models and GPS systems, and thus aid machine operators to e.g. control the position of a road grader's blade. Many machine control system ...

, industrial automation, navigation equipment, spacecraft flight software, and medical instruments in general. Because of their

versatility Versatile may refer to: *In botany, versatile refers to anthers that swing freely at their attachment to the filament *Versatile (sex), person who enjoys both being dominant and submissive, and may alternate between the two in sexual situations ...

, operating systems based on the Linux kernel can be also found in mobile devices that are actually

touchscreen A touchscreen or touch screen is the assembly of both an input ('touch panel') and output ('display') device. The touch panel is normally layered on the top of an electronic visual display of an information processing system. The display is ofte ...

-based embedded devices, such as

smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...

s and tablets, together with

personal digital assistant A personal digital assistant (PDA), also known as a handheld PC, is a variety mobile device which functions as a personal information manager. PDAs have been mostly displaced by the widespread adoption of highly capable smartphones, in part ...

s (PDAs) and

portable media player A portable media player (PMP) (also including the related digital audio player (DAP)) is a portable consumer electronics device capable of storing and playing digital media such as audio, images, and video files. The data is typically stored ...

s that also include a touchscreen. This is a challenge for most learners because their computer experience is mainly based on GUI (

Graphical user interface The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows User (computing), users to Human–computer interaction, interact with electronic devices through graphical icon (comp ...

) based interaction with the machine and high-level programming on the one hand and low-level programming of small

microcontroller A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs ( processor cores) along with memory and programma ...

s (MCU) on the other hand while the concept of command line interfaces is widely unknown.

History

The Linux kernel has been ported to a variety of CPUs which are not only primarily used as the processor of a desktop or server computer, but also ARC, ARM, AVR32, ETRAX CRIS, FR-V, H8300, IP7000, m68k, MIPS, mn10300,

PowerPC PowerPC (with the backronym Performance Optimization With Enhanced RISC – Performance Computing, sometimes abbreviated as PPC) is a reduced instruction set computer (RISC) instruction set architecture (ISA) created by the 1991 Apple– IBM ...

SuperH SuperH (or SH) is a 32-bit reduced instruction set computing (RISC) instruction set architecture (ISA) developed by Hitachi and currently produced by Renesas. It is implemented by microcontrollers and microprocessors for embedded systems. At t ...

, and Xtensa processors. Linux is also used as an alternative to using a proprietary

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

and its associated

toolchain In software, a toolchain is a set of programming tools that is used to perform a complex software development task or to create a software product, which is typically another computer program or a set of related programs. In general, the tools for ...

Variants

The Embeddable Linux Kernel Subset is a

Linux distribution A Linux distribution (often abbreviated as distro) is an operating system made from a software collection that includes the Linux kernel and, often, a package management system. Linux users usually obtain their operating system by downloading on ...

that fits on a

floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined ...

for outdated or low resource hardware.

Devices coverage

Due to its low cost (freely available source code) and ease of customization, Linux has been shipped in many consumer devices. Devices covering PDAs (like the Sharp Zaurus family), TomTom GPS navigation devices, residential gateways like the Linksys WRT54G series or

s such as the

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola ...

exz series, Openmoko handsets, devices running Sailfish OS developed by Jolla like Jolla C and Intex Aqua Fish and the Nokia N900 and Nokia N9.

Android Android may refer to: Science and technology * Android (robot), a humanoid robot or synthetic organism designed to imitate a human * Android (operating system), Google's mobile operating system ** Bugdroid, a Google mascot sometimes referred to ...

, a Linux-kernel-based operating system acquired and extended by

Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...

and introduced in 2008, has become a highly competitive platform for

s and tablets. In July 2012, Android's smartphone market share in the United States was at 52%, reaching 82% worldwide in Q2 2015.

Communities

With the availability of consumer embedded devices, communities of users and developers were formed around these devices: replacement or enhancements of the

shipped on the device has often been made possible thanks to availability of the

source code In computing, source code, or simply code, is any collection of code, with or without comment (computer programming), comments, written using a human-readable programming language, usually as plain text. The source code of a Computer program, p ...

and to the communities surrounding the devices. Due to the high number of devices, standardized build systems have appeared, including Yocto, OpenEmbedded, Buildroot,

OpenWrt OpenWrt (from ''open wireless router'') is an open-source project for embedded operating systems based on Linux, primarily used on embedded devices to route network traffic. The main components are Linux, util-linux, musl, and BusyBox. A ...

, and LTIB.

Platform usage

The advantages of embedded Linux over proprietary embedded operating systems include multiple suppliers for software, development and support; no royalties or licensing fees; a stable kernel; the ability to read, modify and redistribute the source code. The technical disadvantages include a comparatively large memory footprint (kernel and root filesystem); complexities of user mode and kernel mode memory access, and a complex

device driver In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and o ...

s framework.

Limitations

Not every embedded Linux distribution is required to or meets real-time requirements. This is particular relevant for safety critical applications and systems. Projects to develop real-time and safety-critical support are Real-Time Linux (PREEMPT_RT) and ELISA (under

Linux Foundation The Linux Foundation (LF) is a non-profit technology consortium founded in 2000 as a merger between Open Source Development Labs and the Free Standards Group to standardize Linux, support its growth, and promote its commercial adoption. Addi ...

). Real Time Linux project aims mainlining the PREEMPT_RT-version. In order for the electronic system to run fully-fledged Linux OS and have multitasking it has to have enough operative memory (or replacing such) and

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 ...

implementing

virtual addressing In computing, a virtual address space (VAS) or address space is the set of ranges of virtual addresses that an operating system makes available to a process. The range of virtual addresses usually starts at a low address and can extend to the hig ...

to ensure compatibility with software running on Linux.

References

External links

Embedded Linux course on youtube (Zedboard)
* *
Embedded Linux mailist list archive

Embedded Debian Project
(obsolete)
VxWorks to Embedded Linux: a Success Story

Embedded Linux Wiki: A centralized place for sharing Embedded Linux Knowledge
{{Embedded systems Embedded operating systems