From Wikipedia, the free encyclopedia
Embedded Linux is the use of a Linux operating
system in embedded computer
systems such as mobile
phones, personal digital assistants,
media players, set-top boxes, and other consumer electronics devices, networking
equipment, machine control, industrial
automation, navigation equipment and medical instruments.
According to survey conducted by Venture Development Corporation,
Linux was used by 18% of embedded engineers.[1]
Differences
from other Linux operating systems
Unlike desktop and server versions of Linux, embedded
versions of Linux are designed for devices with relatively limited
resources, such as cell phones and set-top boxes. Due to concerns
such as cost and size, embedded devices usually have much less RAM and secondary storage than desktop computers,
and are likely to use flash memory instead of a hard
drive. Since embedded devices serve specific rather than
general purposes, developers optimize their embedded Linux distributions to target specific
hardware configurations and usage situations. These optimizations
can include reducing the number of device drivers and
software applications, and modifying the Linux kernel to be a
real-time operating
system.
Instead of a full suite of desktop software applications,
embedded Linux systems often use a small set of free software
utilities such as busybox, and replace the glibc C standard
library with a more compact alternative such as dietlibc, uClibc, or Newlib.
Development
Linux has been ported to
a variety of processors not suited for use as the processor of
desktop or server computers, such as various CPUs including ARM, avr32, blackfin, cris, frv,
h8300,IP7000
m32r, m68k, mips, mn10300, powerpc, sh, or xtensa processors, as an alternative to
using a proprietary operating system and
toolchain.
The advantages of embedded Linux over other embedded
operating systems include no royalties or licensing fees, a
stable kernel, a support base that is not restricted to the
employees of a single software company, and the ability to modify
and redistribute the source code. The disadvantages include a
comparatively larger memory footprint (kernel and root filesystem),
complexities of user mode and kernel mode memory access and complex
device drivers framework.
Special
interest groups
Several industry groups have formed to foster use of Linux in
embedded applications. These include: the CE Linux Forum, founded in 2003 to aid
the inclusion of embedded features in the main Linux kernel branch;
the Linux
Foundation (formerly Open Source Development
Labs); the Linux Phone Standards
Forum, created in 2004 to pursue a standard applications
environment for Linux-based mobile phones and "converged devices";
the LiMo
Foundation, founded in 2006 by Motorola, NEC,
Panasonic, Samsung, DoCoMo, and Vodafone to establish a set of interfaces and
standard reference components to improve the third-party mobile
phone developer base; and the San Francisco, California-based Embedded Linux Consortium,
which, until its 2005 closure and transfer of operations to the
Linux Foundation, included IBM, Intel, LynuxWorks, and others,
and focused on application programming
interface standardization. The Embedded Linux Consortium
produced the ELCPS (Embedded Linux Consortium Platform
Specification) which was intended as a guide to developers of
embedded Linux devices as to what functionality should be included
in order to provide a standard platform supporting application
portability. Kevin Dankwardt spoke up about the ELC's efforts and
later contributed significantly to the standard.
Commercial embedded
hardware and platforms
- Motorola mobile
telephones, generally based on MontaVista Linux, include the RAZR² V8, ROKR E2, ROKR E6, A780, E680, A910, A1200, U9, E8, MOTOZINE ZN5 and others
- MontaVista Software including MontaVista
Linux, Mobilinux,
Carrier Grade Edition, and Professional Edition
- Openmoko's Neo 1973 or FreeRunner
- Nokia's N900 N810 N800 770
- Android
- Linksys WRT54G
version 4 or earlier
- Panasonic P901i and NEC N901ic mobile phone
- Philips LPC3180
- UTstarcom [DV007]
- Digi Connect
ME and ConnectCore modules
- gumstix basix, connex
and verdex
- Cisco
MDS and Nexus switches
- LCD and plasma TVs from LG, Panasonic, Samsung, Sony [2]
- TomTom GPS navigation systems
- Armadeus
Systems i.MX based modules: APF9328 and APF27
- Amazon
Kindle
Vendors
See also
References
Further
reading
External
links
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