Linux on embedded systems

{{Short description|Uses in embedded systems}}  The Linux operating system is prevalent in embedded systems. As of 2024, developer surveys and industry reports find that Embedded Linux is used in 44%-46% of embedded systems.<ref>{{cite web |title=Embedded Systems Statistics By Market Size And Technologies |url=https://electroiq.com/stats/embedded-systems-statistics |website=Electro IQ |date=24 February 2025 |access-date=April 20, 2025}}</ref><ref>{{cite web |title=The Eclipse Foundation Unveils 2024 IoT & Embedded Developer Survey Results |url=https://newsroom.eclipse.org/news/announcements/eclipse-foundation-unveils-2024-iot-embedded-developer-survey-results |website=Eclipse Foundation |date=3 December 2024 |access-date=10 May 2025}}</ref><ref>{{cite web |title=Wind River Continues Long-Standing #1 Ranking in Edge Operating System Platforms |url=https://www.businesswire.com/news/home/20250417872811/en/Wind-River-Maintains-Long-Standing-1-Ranking-in-Edge-Operating-System-Platforms|website=businesswire|access-date=10 May 2025}}</ref> Due to its versatility, its large community of developers, as well as its adaptability to devices with size and power constraints, Linux is a popular choice for devices used in edge computing<ref>{{cite web |title=2023 State of the Edge Report |url=https://lfedge.org/introducing-the-2023-state-of-the-edge-report-navigating-the-frontier-of-edge-computing |website=LFEdge}}</ref> and autonomous systems.{{citation needed|date=April 2025}}

==History==

{{Main|Linux kernel version history}} : additional source for this section <ref name="2net">{{cite web |title=Embedded Linux Timeline |url=https://2net.co.uk/embedded-history |website=2net}}</ref>

=== Early days ===

Prior to becoming the de-facto standard for microprocessor-based devices,<ref>{{cite book |last1=Kingman |first1=Henry |title=The History of Embedded Linux & Best Practices for Getting Started |date=July 2013 |publisher=Linux Foundation |page=2}}</ref> a Linux distribution was created for the Linux Router Project, with the intent of transforming PCs to routers. === Introduction of μClinux === Starting in the late 1990s and the first decade of the 21st century, the introduction of μClinux enabled ports to a large variety of microprocessors, especially those without a memory management unit (NOMMU).<ref>{{cite web |last1=Opdenacker |first1=Michael |title=Introduction to uClinux |url=https://bootlin.com/doc/legacy/uclinux/uclinux_introduction.pdf |website=bootlin.com}}</ref> Linux is also used as an alternative to using a proprietary operating system and its associated toolchain.<ref name="vxworks-migration">{{cite web | url = http://www.mvista.com/download/Migrating-VxWorks-apps-to-embedded-Linux-slides-with-notes.pdf | archive-url = https://web.archive.org/web/20140210185142/http://www.mvista.com/download/Migrating-VxWorks-apps-to-embedded-Linux-slides-with-notes.pdf | title = Migrating VxWorks applications to Linux | year = 2008 | access-date = 2013-11-13 | archive-date = 2014-02-10 | publisher = Monta Vista Software }}</ref>

=== Introduction of BusyBox === The introduction of BusyBox in 1999 enabled packaging of critical tools in an embedded system, with a minimal footprint.

=== The ARM-Linux synergy ===

ARM processors are prevalent in many embedded devices, due to their low costs, low power consumption, and low heat generation. The open source nature, the flexibility, and the stability of Linux contributes to its widespread adoption to ARM devices.<ref>{{cite web |last1=Vuong |first1=Kent |title=Linux on ARM: The Future of Operating Systems in a Connected World |url=https://www.linkedin.com/pulse/linux-arm-future-operating-systems-connected-world-kent-vuong/ |website=LinkedIn}}</ref>

=== Development toolchains === The development of the GNU cross-compiler facilitated the adoption of Linux embedded to many processors.

=== Android ===

In 2008, Android 1.0 was released, based on the Linux kernel. Android, a Linux-kernel-based operating system acquired and extended by Google and introduced in 2008, has become a highly competitive platform for smartphones and tablets. In time, Android would become the most successful Linux embedded distribution.<ref name="2net" />

=== Real-time support === thumb|Linux embedded Real Time Evolution

Not every embedded Linux distribution is required to or meets real-time requirements.<ref>{{cite book |last1=Erciyes |first1=K. |title=Distributed Real-Time Systems |chapter=Real-Time Operating Systems |series=Computer Communications and Networks |date=2019 |pages=65–88 |doi=10.1007/978-3-030-22570-4_4 |isbn=978-3-030-22569-8 }}</ref><ref>{{Cite web|title=What does it mean to say "linux kernel is preemptive"?|url=https://stackoverflow.com/questions/5283501/what-does-it-mean-to-say-linux-kernel-is-preemptive|access-date=2021-03-08|website=Stack Overflow}}</ref> This is particularly relevant for safety critical applications and systems.<ref>{{cite book |last1=Oshana |first1=Robert |title=DSP Software Development Techniques for Embedded and Real-Time Systems |chapter=Real-Time Operating Systems for DSP |date=2006 |pages=261–320 |doi=10.1016/B978-075067759-2/50010-7 |isbn=978-0-7506-7759-2 }}</ref>

The original Linux kernel was not suitable for real-time tasks due to its non-deterministic behavior<ref>{{cite journal |last1=Reghenzani |first1=Federico |title=The real-time linux kernel: A survey on Preempt_RT |journal=ACM Computing Surveys |date=2019 |volume=52 |page=1-36 |doi=10.1145/3297714 |hdl=11311/1076057 |hdl-access=free }}</ref>

Early attempts to provide real-time support, such as RTAI were based on a real-time kernel alongside the standard kernel.

In 2005, the PREEMPT_RT project was initiated to provide a patch to the Linux kernel.<ref>{{cite web |title=Real-Time Linux Wiki |url=https://archive.kernel.org/oldwiki/rt.wiki.kernel.org |website=Archive Kernel.org}}</ref><ref>{{cite web |title=PREEMPT_RT patch versions |url=https://wiki.linuxfoundation.org/realtime/preempt_rt_versions |website=Linux Foundation}}</ref>

In 2024, the PREEMPT_RT patch was fully merged into the Linux kernel for supported architectures.

=== IoT === The open source nature and security features of Linux have contributed to its prevalence in devices on the edge and IoT systems.<ref>{{cite web |last1=Cintay |first1=Emre |title=The Impact of Linux on Emerging Technologies: IoT, AI, and Beyond |url=https://medium.com/%40Chinacolt/the-impact-of-linux-on-emerging-technologies-iot-ai-and-beyond-4b9ca9a06cf2 |website=Medium |access-date=24 April 2025}}</ref> Correspondingly, the demand for the real-time capabilities described in the previous subsection, is driven by the proliferation of IoT devices.

=== Containerization === The emerging technologies of the fourth industrial revolution have driven further enhancements to the Linux kernel, notably the adoption of containerization.<ref>{{cite web |title=Guide to Building Embedded Linux Systems with Containers |url=https://pantacor.com/embedded-linux/guide-to-building-embedded-linux-systems-for-iot-with-containers |website=Pantacor}}</ref>

==Devices coverage== Due to its freely available source code and ease of customization, Linux has been shipped in many consumer devices. Starlink and SpaceX use embedded Linux on their constellations and rockets.<ref name= spaceUses >Tim Bird [https://www.youtube.com/watch?v=3-areQvSKTg July 2022] [https://eoss2023.sched.com/event/1LcNH/status-of-embedded-linux-tim-bird-sony-electronics?iframe=no (June 2023) Status of Embedded Linux]</ref> The Embeddable Linux Kernel is a lightweight and customizable Linux distribution appropriate for low resource hardware.<ref>{{Cite web|title=ELKS: The Embeddable Linux Kernel System|url=https://github.com/jbruchon/elks|access-date=2021-04-12|website=GitHub.com/elks}}</ref> Like the synergy with the ARM architecture as mentioned in #The ARM-Linux Synergy, Linux embedded has evolved with hardware technologies like system on a chip and Single-board computer, networking standards, and memory devices.<ref>{{cite book |last1=Yaghmour |first1=Karim |title=Building Embedded Linux Systems |date=2008 |publisher=O'Reilly |edition=2nd}}</ref> (example: Raspberry Pi)

==Linux embedded ecosystems== With the availability of consumer embedded devices, communities of users and developers were formed around these devices: replacement or enhancements of the Linux distribution shipped on the device have often been made possible thanks to availability of the source code and to the communities surrounding the devices.

=== Build systems === Alongside the evolution of the Linux kernel, build systems evolved to support the building of an optimized operating system for an embedded device.

Before the emergence of these build systems, developers manually built toolchains and compiled each component of the embedded distribution (kernel, libraries, applications).<ref>{{cite book |last1=Yaghmour |first1=Karim |title=Building Embedded Linux Systems |date=2003 |publisher=O'Reilly}}</ref> Currently, there are several solutions, some full build systems, others are supporting tools.

* Yocto Project * Buildroot * BitBake * CMake * OpenWrt * Open Embedded

=== Development tools === * GNU Compiler Collection - cross compiler * GDB * QEMU * Eclipse IDE

==Variants== === Summary table of variants (2025) === {|class=wikitable |+ ! Category of Variant ! Examples |- | Networking Devices | OpenWRT, firmware variant DD-WRT |- | IoT Devices | [https://ubuntu.com/core Ubuntu Core], [https://www.balena.io/os Balena OS], [https://www.raspberrypi.com/software Raspberry Pi OS] |- |Automotive | [https://www.automotivelinux.org/ Automotive Grade Linux] |- | Safety Critical Applications | [https://www.windriver.com/products/linux Windriver Linux (commercial product)], [https://elisa.tech/ Enabling Linux in Safety Applications (ELISA)], |- | High reliability Industrial Applications | [https://www.torizon.io/torizon-os Torizon], Xenomai |}

==See also== {{Portal|Linux}}

{{div col|colwidth=22em}} * Articles: ** Convergent Linux Platform ** Linux range of use ** Linux for mobile devices ** TinyLinux * Products/Distributions: ** Armbian - specialised for ARM single board computers ** BusyBox ** BuildRoot ** Debian – used on Raspberry Pi ** Embeddable Linux Kernel Subset ** Emdebian Grip ** Familiar Linux ** Google's Android well-known type of embedded Linux, e.g. on smartphones ** Mobilinux ** OpenMoko ** OpenWrt ** DD-WRT ** RTLinux ** Tizen – embedded Linux for smartphones ** Ubuntu - Core and Server, on Raspberry Pi, x86, ARM ** μClinux * Vendors: ** Access Co. ** Canonical with [https://ubuntu.com/core Ubuntu Core] and Ubuntu Server ** LynuxWorks ** Mentor Graphics ** MontaVista Software ** Wind River Systems ** TimeSys ** ENEA AB ** [https://www.suse.com/embedded SUSE] *Other: ** Preemption (computing) ** Safety-critical system {{div col end}}

==References== {{Reflist}}

==Further reading== * {{cite book|last=Weinberg|first=Bill|title=Uniting Mobile Linux Application Platforms|publisher=LinuxPundit.com|date=July 2008|pages=18|url=http://www.linuxpundit.com/cv/docs/Platforms_WP_LP.pdf|access-date=2009-05-08|archive-url=https://web.archive.org/web/20120216071824/http://www.linuxpundit.com/cv/docs/Platforms_WP_LP.pdf|archive-date=2012-02-16|url-status=dead}}

==External links== * [https://www.linuxfoundation.org/ Linux Foundation] * [https://www.youtube.com/watch?v=92-uLpWIRaI&list=PLo7bVbJhQ6qxRyrF7CSW3wXcbmmFl9z7-&index=1 Embedded Linux course on YouTube (Zedboard)] * {{cite web|url=http://linuxdevices.com/ |title=News and technical articles concerning embedded Linux |archive-url=https://archive.today/20130103162309/http://www.linuxfordevices.com/ |archive-date= 3 January 2013 |url-status=dead }} * [http://www.spinics.net/lists/linux-embedded/ Embedded Linux mailist list archive] * [http://www.emdebian.org Embedded Debian Project] {{Webarchive|url=https://web.archive.org/web/20060630015856/http://www.emdebian.org/ |date=2006-06-30 }} (obsolete) * [http://www.linuxjournal.com/article/6272 VxWorks to Embedded Linux: a Success Story] * [https://elinux.org/ Embedded Linux Wiki: A centralized place for sharing Embedded Linux Knowledge]

Category:Embedded Linux Category:Embedded operating systems