Need an embedded operating system? Get a long notepad and a pot of coffee, because there are literally hundreds to choose from. Custom microkernels, Unix look-alikes … there’s even a couple of embeddable MS-DOS clones out there. Microsoft has tried twice to bring order and a dominant player to the market–first with the marginally successful Windows CE, then with Embedded Windows NT.

But it may actually be Linux that ascends to the top of the heap in the $3.5 billion-per-year market for embedded system development tools. Enthusiasm for embedded Linux systems has grown dramatically over the past two years–even Linus Torvalds has gone on the record to say that it should be a priority for the open source OS.

Roughly speaking, an embedded device is anything internally sophisticated enough to be considered a computer, but which does not look like a traditional server or desktop machine. Often, but not always, embedded devices are crafted for a single or a very narrow range of uses. They range from hands-off, “black box” devices like an Internet router or a network-attached storage device, to things that touch consumers every day, like cash registers or the credit card reader at a pay-at-the-pump gas station.

Despite some initial criticism that the full-size version of Linux could never be shoehorned into the tight requirements of an embedded device, a number of embedded Linux solutions are cropping up. The TiVo set-top TV box, for example, a joint effort from Philips Electronics and startup TiVo, Inc., of Sunnyvale, Calif., runs Linux.

The advantages Linux offers for embedded systems are largely the same strengths that make it popular as a server operating system: low cost, high reliability, and the availability of the source code. And the large number of programmers at work on core Linux OS development, as well as the even greater number of Linux-literate developers, make the task of improving a device’s operating software and finding qualified application programmers considerably easier.

The Embedded Linux Consortium, barely a couple of months old, already boasts 78 member organizations, most of which take the venture seriously enough to front the $5,000 premium level membership cost. “Promotion of Linux as a solution for embedded applications is our goal,” says Murry Shohat, acting executive director. “The key is marketing and promotion. The longer-range goal is what you see many consortia doing: standards and intellectual property promotion.” In other words, don’t count on the group to vote on a rigid spec for real-time Linux any time soon.

Staking a Claim

Established players in the embedded operating systems arena, such as MontaVista and TimeSys, have staked their claim to the emerging market with their own device-targeted Linux distributions. Perhaps nowhere is this phenomenon more evident than at Lynx Real-Time Systems, which built its business on the venerable, “Unix-like” LynxOS real-time operating system. Not long ago, Lynx unveiled its own distribution of Linux for the embedded market, dubbed BlueCat. And just so nobody could accuse them of not being serious about Linux, the company changed its name to LynuxWorks.

“We believe in the open source movement,” says Luke Dion, vice president of technology and strategic planning for the San Jose, CA-based firm. The open source version of BlueCat contains device (and device-less) specifications and configurations not normally found in desktop Linux distributions. “If our competitors are smart, they’ll pick up our modifications [for free,]” says Dion.

Like most corporate embedded Linux developers, however, LynuxWorks sells proprietary embedding, development, and testing software for BlueCat. And while the company has had an internal debate on the merits of opening up the source code to its original LynxOS, it has decided to keep the product as a closed platform. “Many of our customers are in highly competitive markets,” Dion says, “and they’re very concerned that if LynxOS were open source, the enhancements and modifications they make for competitive edges in their markets would have to be turned over to some open source community.”

It’s All in the Tools

The distinction between the familiar mainstream Linux distributions and the new breed of embedded Linux amounts in most cases to the addition of proprietary development tools. The commercial version of Lineo’s Embedix, for example, features closed-binary tools that greatly expand the configuration options of the kernel, making it easier, in Lineo’s terms, to “granularize and cut up” Linux for specific embedded applications. “The Linux kernel and all the associated pieces are open source, but the technology we add to it that makes it possible to shrink the operating system and fine tune it to a very high level is obviously proprietary,” says Lineo’s Drabik.

“There are plenty of free [embedding] tools if that’s what you prefer to use,” says Rick Learbaum, executive editor of ZDNet’s LinuxDevices.com information site. “There are real-time extensions and patches, and techniques for loading Linux from ROM. On the other hand, development tools are a good area for companies to add value–and create a profitable business–around Linux,” he says.

Says Shohat, “I believe that the tools issue is always going to be won by selling efficiency. Whether tools use open source or proprietary technology is not going to matter to the customer.” Drawing on years of experience in embedded device development, as well as existing licenses from hardware companies that are reluctant to release their specifications to the open source community, the traditional OS companies often have a first-mover advantage when it comes to tools.

Whether the tools are proprietary or open source, the real question for embedded Linux adopters is: will the Linux development community respond to the world of single-board computers and “black boxes” the way they have to Linux’s traditional environments?

One thing standing in the way is the hardware. For the desktop and server version of Linux, says Volker Wigand, CEO of SuSE Inc., “the underlying hardware is the PC, which [developers] already have. For the embedded market, you have [embedded] devices, evaluation kits … usually, you have to have a reason to work on embedded Linux.”

But with major electronics companies such as cell phone manufacturer Nokia turning to ROM-based Linux to drive their consumer and industrial devices, anything is possible. “Never underestimate the programming bandwidth of over 12,000 open source developers around the world,” says Lineo’s Drabik. And if they adopt the embedded market with the same enthusiasm they’ve shown for Linux on servers and desktops, embedded computing could be just another step for Linux on the path to World Domination.

Jason Compton is an Evanston, IL-based technology journalist. He is a regular contributor to Linux Magazine, Smart Business, and the Chicago Tribune.