Next up: Linux for Internet appliances

Linux has been at the center of a great deal of activity lately. One sign of the ferment swirling around the open source operating system is that it is starting to appear in cell phones, set-top boxes and other Internet appliances.

This development is remarkable because Linux, primarily a server operating system (OS), was not originally intended to be used in this fashion, analysts say. Now it's possible that a wave of new Internet devices will supplant PCs as our primary computing devices, and many of them will run versions of Linux suitable for small devices.

For example, Embedix - an embedded version of Caldera Systems' OpenLinux produced by Lineo, an offshoot of Caldera - has attracted the attention of cell phone maker Motorola. Coollogic is now selling Linux embedded in a television set-top box, first created by On Channel, which Coollogic acquired in December 1999. And another young company, MontaVista Software, has produced its own version of real-time Linux called Hard Hat Linux.

However, for Linux to be an embedded OS choice, a few obstacles need to be overcome.

A short while ago, embedded systems observers said these companies were trying to fit a square peg into a round hole. These critics asserted that Linux is too bulky, too server-oriented, too lacking in real-time characteristics to compete with the Palm OS from Palm Computing, which is used in its Palm series of handheld computers; Epoc from Symbian, a consortium of telecommunications companies; or the traditional real-time OSes from Lynx Real-Time Systems, Wind River Systems and others.

But there is an increasing body of opinion that the experimentation with Linux will help fuel the proliferation of Internet access devices. "The question is not whether Linux will play a role in embedded systems, but, 'How much of a role will it play?' " says Chris Schoppa, director of product development at Hewlett-Packard's embedded software operations.

"Linux will be competitive with Windows NT and will perhaps overtake it. It will play a significant role in the market," says Jerry Krasner, director of Electronics Market Forecasters.

Both Linux and Windows NT serve as development platforms for embedded systems and also as the OS to run an appliance. In an Electronics Market Forecasters survey of embedded developers, 25 percent indicated they would use Linux this year, compared with 10 percent in 1999, Krasner says.

Linux, like Windows NT, tends to be used for larger embedded applications, such as those in specialized servers and manufacturing processes, Krasner says. The question remains: Which OS will be found on consumer and Internet access devices?

Linux is still viewed as overweight in some quarters for small consumer and Internet thin-client devices. The alternative is likely to be the Palm OS or established, embeddable OSes such as Lynx or Wind River.

That's a view that will change, predict officials at Cygnus Solutions, the embedded tools firm recently acquired by Red Hat. "We have demonstrated running a 355-kilobyte Linux," says Red Hat Chief Technology Officer Michael Tiemann. "The rate at which new embedded Linux devices are springing up is amazing."

Part of the surprise is that standard Linux distributions, which have grown into the 12-megabyte, 16-megabyte and 17-megabyte range, can reverse direction and shrink back into the kilobyte range. Tiemann acknowledges that 355-kilobyte Linux is little more than the system kernel accessing a microprocessor. Nevertheless, Linux's modular structure of a kernel surrounded by nearly 600 service modules lets developers strip away code as well as add to it. At 355 kilobytes, "there is no user interface," a drawback on some Internet appliances, Schoppa notes.

If Linux can be stripped down to an embedded system, it has a powerful argument on its side as manufacturers consider producing new Internet devices. Lynx, for example, launched its own version of embedded Lynx rather than continuing to push only its proprietary LynxOS. BlueCat Linux became available from Lynx this month.

"Embedded appliances are of necessity very cost-sensitive. And Linux, of course, is free," says Greg Ungerer, chief developer at Australia-based embedded Linux firm Moreton Bay.

"Name-brand companies are looking seriously at Linux in embedded devices. Nokia [the Finland-based mobile phone manufacturer] is now looking at product issues, what microprocessor to use," Tiemann says.

Still, There Are Hurdles.

Experienced embedded systems analysts say Linux does not have the scheduler of an embedded OS, which can pre-empt some processes in favor of others and handle real-time data feeds. "Standard Linuxes still have a fairly primitive process scheduler," HP's Schoppa says.

But Krasner says MontaVista's Hard Hat contains a scheduler modified for real-time operations. Other parties have - or are working on modifying - the scheduler, including Lineo and Zentropix, which has optimized its Realtime Linux 2.2 for embedded system operations.

Improved Linux schedulers "are only a little ways off," Krasner says.

These scheduler modifications are not standard in any of the well-known Linux distributions, so each real-time Linux supplier is making changes, leading to a variety of versions that application developers must master to reach across several markets, Schoppa says. He notes that HP considered Linux for a thin client, but no longer plans on building the device.

With the increasing amounts of memory on thin clients and Internet devices, embedded Linux is becoming much more feasible, he adds.

Linux's open source nature also appeals to the small-device designers and manufacturers. It's not only free, it can be modified to fit the task at hand, which frequently means dispensing with many elements of the OS.

"A megahertz of processor power running Linux is better than a megahertz running NT. You don't have all the extra components that have to run in Windows or Windows CE. You don't have to be a jack of all trades," says Edward Gharfari, vice president of marketing at Coollogic, which is working on personal digital assistants and other thin clients that will run embedded Linux.

An issue remains of whether a small Internet appliance company is in a position to support a device with a version of embedded Linux that is unique to it, Schoppa says. The other embedded systems under the control of one company - such as those from Microsoft and Wind River - come with a clearer support message, he says.

Gharfari concedes that Linux is not going to run every Internet device, but he says: "There appears to be a sweet spot for a device that can access the Internet, send and receive e-mail, and surf the Net." Such a device would be less than a laptop but more than a cellular phone, and its arrival is imminent.

Linux, Gharfari says, is the logical OS for such a device because of the wide range of software developers who can use it, and its potential to serve as an integrating force between the thin client, Web server and other Internet servers, all running Linux.

Building Internet applications will become more like building a house. When it's time to do doors and windows, Gharfari says, "you don't want to build your own. You want to buy them on the open market from a standard supplier." Such a supplier will be targeting Linux, he adds.