Embedded Linux

• Probably the best known embedded Linux is from Lineo, which is the embedded portion of Caldera. Their distribution, Embedix, runs on Power PC as well as x86 platforms. This won the 'Best New Application' award in Linux Journal's 1999 Editors' Choice Awards. There is an interesting interview with Lyle Ball from Lineo in Linux Journal. Also Lineo have announced (or here) that they will be working with Elitegroup Computing and Bast, Inc, to provide the Linux kernel and Embedix Browser for set-top-boxes designed for use in hotels.
• Another company offering embedded Linux support is Monta Vista who produce Hard-Hat Linux. Here is a press release from them, about releasing CompactPCI backplane software as open source. They have also contributed an article to LinuxDevices.com about why "there are strong technical and business reasons to consider using Linux for your next embedded development project". They have also announced that it will be embedded in Kerbango, Inc.'s stand-alone "Internet radio" product.
• Cygnus have also announced EL/IX, a standard API which can be supported on both Linux and standard RTOS's (of course the first implementation will be on ECos!). Cygnus are now owned by RedHat (here is the press release, some comments from RedHat and some reactions from Linux Journal).
• An interesting collaboration has taken place to generate a version of Linux suitable for deployment on PowerPC embedded systems. The standard Linux distribution Yellow Dog Linux (from Terra Soft Solutions, Inc) has been combined with the real-time Linux variant RTLinux, from FSM Labs by Synergy Micros, when they call it `Industrial Linux'. Synergy Micros produce a range of SBC (single board computers) with support for SMP, in both VME and CompactPCI format.
• Another company offering a real-time Linux distribution based on a `conventional' real-time kernel is Lynx. Their BlueCat distribution also runs Linux as a task on top of their LynxOS real-time OS. For some general background reading they have an interesting paper on why Linux is of interested to embedded systems developers (with a `slight' bias towards a particular solution!).
• Another embedded Linux distribution is White Dwarf from EMJ Embedded Systems.
• Integrated Software & Devices Corporation (ISDCorp) has announced that it is shipping "Royal Linux", ISDCorp's port of Linux kernel 2.2.1 for embedded systems. Currently available for ARM, it should be available for MIPS, Motorola 68K/Coldfire and Power PCs shortly.
• Another port based on uClinux is available for the Axix ETRAX 100. This is available from here. An interesting feature of this port is the inclusion of a Bluetooth stack and a Journaling Flash File System, JFFS.

• An in-car MP3 player from empeg. This won the 'Best New Gadget' category of Linux Journal's 1999 Editors' Choice Awards.
• An announcement from Nokia that they will use Linux in a future STB.
• A press release from Lineo that with MeterNet they will co-develop the "industry's first linux-based internet set-top device".
• Another Linux based set-top-box has been announced involving USA Video Interactive, Eagle Wireless and Urbana.ca. This one will offer video-on-demand, and
• A Press release describes how BroadbandMagic.com now support Linux on their 'Convergence' Set-top-box.
• TiVo produce a hard disk drive video recorder and electronic program guide system. Both the STB and servers run Linux. The changes make to the Linux kernel and some selected tools are available from their web site. They have also issued a press release (Jan 7, 2000) stating that future versions will run the Liberate web browser. Also here is an editorial from Nicholas Petreley (LinuxWorld) who trys out a TiVo box, and likes what he finds.
• Netgem produce the `netbox', a range of Set-Top-Box's for web browsing and e-mail, using Linux as the kernel.
• Morton Bay produce a small family of VPN routers called NETtel which run uClinux on a ColdFire. An engineer there has made a simple modification which also allows the board to act as an MP3 player! They also provide a development system (called eLIA) which provides both ColdFire based hardware and Linux software, which allows other companies to use this system for their own products.
• Picazo have announced the availability of a Linux-based private branch exchange (PBX) system.
• Lernout & Hauspie have released a prototype PDA (called Nuk), providing speech recognition and wireless, all running on top of Linux.

• linuxjournal has run a couple of articles:
  • Embedding Linux in a Commercial Product.

    Most Linux systems run on PC platforms; however, Linux can also be a reliable workhorse for embedded systems. This article gives an overview of embedded systems and demonstrates what is involved in using Linux in a commercial embedded system.

    This was taken from a special issue on embedded systems.

  • Open Source Software for Real-Time Solutions

    Much hype is circulating in the industry today about open-source software and Linux. These discussions have focused on how Linux represents the first major threat to Microsoft's domination of the desktop. However, open-source software is also moving into the embedded real-time marketplace. Last year, Cygnus Solutions unveiled a new initiative called eCos (embedded Cygnus operating system). eCos is available as both open source and royalty free. Today, eCos has been downloaded by well over 10,000 developers. Why didn't Cygnus choose Linux as its open-source real-time alternative? This article will compare and contrast these two alternatives and explain why each can have a place in your real-time solution.

• Dr. Dobb's Journal has an article:
  • Linux, Real-Time Linux, & IPC.

    When dealing with real-time systems, the overhead of interprocess communications (IPC) becomes important. The formalized structures that are used in Linux for IPC can carry with them a significant amount of overhead. This can create timing problems for your applications. In this article, I'll examine two of the best IPC mechanisms available under Linux -- FIFOs and shared memory.

• EE Times frequently has articles on Linux.
• RTC had a feature in their September 1999 issue on Linux. A few articles:
  • Linux: Next Common Unix?
  • Just How Real-Time is Linux by James Norton and Trevor Woolven of Zentropic Computing.
  • Running Linux on a Dual Processor/SBC CompactPCI System by James F Ready of MontaVista.
• ESE (Embedded System Engineering) had an article in their October/November 1999 issue:
  • Linux makes progress into RT applications.
  Unfortunately these last two only appear to be available in paper form.
• News.com had an interesting article on Linux from an investors point of view. In particular:

  [Linux] is also is an ideal operating system for appliance computing, a high-growth segment that I've commented on the past.

  ... the appliance model, which is the strategy used by companies like Cobalt Networks. As mentioned before, I am a big believer in appliance computing, with devices tuned for specific tasks. Given this model, low cost and simplicity are key. Tuning Linux for specific tasks addressed by an appliance is relatively easy, and costs are minimized.

• Electronics Design Online had a couple of article:
  • Linux Is A Great Prototyping Tool For Embedded-Hardware Designs written by George Tyler from the Motorola Computer Group.

    To make these new embedded-hardware platforms fully functional, software (e.g., OSs, firmware, communication software, or enabling tools) must be optimized for the new hardware to show off its capabilities and power. The problem is getting software running on the hardware as soon as the hardware is released.

    Using Linux, hardware manufacturers can share early-access hardware, plus prototype or proof-of-concept software, with customers and/or partners without any concerns about software licensing. By sharing this prototype code with real-time-kernel or software vendors, the process of supporting hardware is streamlined. Therefore, when new embeddable hardware becomes available, early-access software is available at the same time.

  • and a forecast for what to look out for in 2000 in the area of Embedded Systems had a section on Linux which recommends:

    ...keep an eye out for what might turn into a real dark horse in the operating-platform race.

    The Linux operating system has turned the market for server operating systems on its head ... will the same thing happen in the embedded system arena?

• Fox News have a Linux channel. There aren't too many articles here yet, but a couple are interesting, in particular:
  • Linux in Your Living Room which discusses the appearance of Linux in domestic applications such as TiVo and Playstation 2:

    The impact of Linux in the home entertainment market could be huge. Its ability to run on multiple platforms, including Intel, Motorola, SGI and Apple, and its open-source kernel that can be modified by lots of developers for any task, give it a tremendous advantage over other operating systems in this market.

• The Gartner Group, Inc produce statistics and reports on the Computing Industry, and have been keeping tabs on Linux for some time. In general they don't think it will have much impact on the office automation area, but a recent article stated that:

  Linux fits where Unix hoped, but failed, to win: as a commodity OS for inexpensive Intel servers and desktops. It solves the enterprise need for budget-tight deployments (e.g., replicated sites, Internet nodes and embedded devices that can be easily scrapped, swapped and upgraded).

• GNet have a couple of technology related articles, in particular an interview with Linus Torvalds, where he mentions Mobile Linux.
• Another interview, this time with Michael Tiemann, CTO at Red Hat, is available from ZDNet.

• EmbedLinux.net founded by Monta Vista.
• EMLAB (Embedded Linux Advisory Board) founded by Lineo.

Also EmbeddedTechnology.com have opened a News & Analysis section focusing on Linux in embedded applications called Linux Beat.

Web pages are typically not designed for viewing on a computer not a television screens. For example the viewer may be a long way away from the screen, which is of low resolution, and typically doesn't have a keyboard. A number of companies are working on ways to improve this:

• Set-Top.com is a service for set-top boxes, games consoles and similar devices which acts as a portal to web sites which have been designed to work on TV's.
• Liberate works from a different perspective, producing a browser which renders normal web content into a form which is more suitable for TV viewing. Liberate is the latest incarnation of Navio (the embedded Netscape spin off) and Network Computers Inc (NCI).

If you see any more links you think would fit here, please let me know.

There are a number of embedded graphics libraries and windowing systems which may be of interest:

• NanoGUI (soon to be moving) is "an attempt to produce an Open Source GUI system for small Linux based systems such as palmtops and embedded POS units."
• Derived from this is Microwindows. This also forms the base for Nano-X. Apparently Opera Software have ported their web browser to this system. Executable size 667K (no idea which processor).

There are a couple of projects aimed at generating small Linux configurations, which use a standard PC where previously custom hardware and software would have been used.

• ELKS (The Embeddable Linux Kernel Subset) is designed to run on 8086 class machines, (i.e. without an MMU) and so, as its name suggests, only supports a subset of the Linux API, and is not build from the 'standard' Linux source base,
• LEM "Linux EMbedded" is a small distribution of i386 linux which provides embedded soft developers a small ( < 8 Mb ) multi-user, networked OS with an X11R6 server.
• Alternatively the Linux Router Project provides a small distribution of Linux which is designed to make "building and maintaining routers, access servers, thin servers, thin clients, network appliances, and typically embedded systems next to trivial".
• Alternatively, another small Linux distribution is PeeWeeLinux.
• A potentially useful piece of software is ZENamp, an embedded MP3 player.
• A potentially interesting (but commercial) product from Icon Labs is an SNMP development environment for Linux.
• A good set of links is available from the linux-embedded site.
• Also MTD, the Memory Technology Device Subsystem for Linux, which provides support for various forms of Flash, some of which allow execute-in-place to reduce RAM requirements.