 | Level: Introductory Judy DeMocker (jdemocker@sprynet.com), Freelance computer journalist
01 May 2001 Judy DeMocker explains why it seems that Linux may win over the embedded market. She takes a look at the conveniences of the open source license and what it means for embedded Linux, at maintaining embedded systems (and their device drivers) with Linux, and being able to offer single-platform support.
Embedded Linux has come a long way since IBM first showcased its Linux wristwatch at PC Expo last summer. Since then more than a dozen distributions of the reduced-footprint OS have appeared, and nearly half of embedded developers are eyeing Linux for upcoming projects, according to a survey of Embedded Systems Programming readers last year. Today more embedded devices use Linux than Nucleus or VRTX, and it's gaining ground on Embedded Windows and pSOS. A dozen Linux devices are on the streets, from TiVO's set-top box to Agenda Computing's VR3 PDA. Now, the Embedded Linux Consortium (ELC) wants to get all the embedded efforts pointed in the same direction with a reference platform specification, due midyear. If that effort succeeds, embedded Linux has a good shot at dominating embedded development in the years to come, say Linux advocates. Now, there are lots of great things about proprietary embedded software; Wind River's VxWorks and homegrown systems rule that space today for good reasons. A closed platform that doesn't break from version to version keeps your third-party software developers happy, and it keeps familiar development tools relevant and useful. Add to that the long-standing relationships commercial RTOS vendors have with the hardware manufacturers to optimize software for each new processor platform. But the overwhelming advantage is with the Open Source OS, for three simple reasons. No per-unit royalty fees or licensing charges
By far the biggest driver in embedded Linux today is the open source licensing agreement, which maintains that source code for the OS is freely available and can be used without licensing or royalty fees. Commercial vendors of embedded Linux have their own fee structures in place, but these rarely include per-unit royalties. For device makers, those per-unit charges can be a big bugaboo when it comes to hitting a $50 or $100 price point, especially if they have to pay $1 to $150 per copy of the OS. "Lately, because of the market dynamics of embedded Linux, more and more of our customers are asking for Linux-based solutions," said Pradyum Sant, strategic marketing manager for Hitachi Semiconductor America, which markets its family of SuperH microprocessors to device manufacturers and helps them select software components for embedded devices. "The reason people are choosing Linux is its reliability and robustness, and because of the open source licensing model. That doesn't mean Linux is free necessarily; it just means that you don't pay royalties. That difference is big if you are shipping products in high volume. People are choosing Linux over homegrown and even established OSes."
Devices need features existing RTOSes can't provide
Increasingly, embedded devices are shipping with more memory, wireless and/or Internet connectivity, and hard disks -- especially consumer devices like PDAs, cell phones, and set-top boxes. That means those devices have requirements for memory protection, security, and support for customizable color GUIs and personal information that existing RTOSes aren't built to handle. Linux is far better equipped to meet those needs than traditional, flat address space RTOSes, according to Dr. Inder Singh, ELC chairman and CEO of LynuxWorks, a San Jose-based company that sells BlueCat Linux and IDE tools to embedded developers. "Embedded devices are becoming servers. And connectivity has really become a substantial part of what they do," said Rick Lehrbaum, founder of ZDNet's LinuxDevices.com Web site. "You can watch as the capabilities of high-end systems spin down into devices that never had intelligence before." A side benefit to Linux is that embedded developers can use the device drivers, applications, and libraries that the open source development community keeps up to date, said Larry Macfarlane, director of Application Environments at Wind River. "It's not Linux our customers want," said Macfarlane. "They like open source software because they like to have the community maintain the device drivers."
The promise of a single platform
Today, shops are saddled with supporting multiple platforms: their embedded platforms, their development environments on their PCs or workstations, and their back-end systems. For some, that means that highly trained and scarce human resources are spending time on sys admin duties, or kludging together data bridges between devices and databases. That, says one developer, is tantamount to reinventing the wheel every time a new application is created. "Supporting multiple platforms is onerous. And manpower in the astronomy community is limited," said Gary Hovey, Project Engineer at the National Research Council's Herzberg Institute of Astrophysics. Hovey's work at the Dominion Radio Astrophysical Observatory, in Penticton, British Columbia, includes developing a real-time image processing system for the James Clerk Maxwell Telescope, located on Mauna Kea, Hawaii. Those eight-processor devices run Wind River's VxWorks and transmit massive amounts of data to a 16-node P3 Linux cluster that handles processing and storage tasks. Embedded Linux could give Hovey's group access to a low-cost development environment, he says, and allow it to run existing software on both real-time and back-end number-crunching systems. In other words, develop once, run everywhere. "The best of all possible worlds would be to be running the same real-time operating system on the server and in the embedded device," Hovey said. That capability will be available soon enough, says Red Hat's Kim Knuttila. Theoretically, a developer could run the same set of applications on an embedded Linux device as on a Linux server by partitioning a standard POSIX API into a set of subsets. For instance, a developer might leave out the file system (or put it into Flash memory) or TCP/IP stack to make for a smaller footprint; she might use embedded Linux as nothing more than a boot loader to initialize peripherals, and have the application take over from there. These options will give programmers more flexibility in how they choose to develop, and which environments they want to code and debug in, Knuttila said. "If you're working with a customized OS environment, you can't test anything in your home world. You would really rather things be as much as possible developed in your home world, where you have all the best tools," said Knuttila, vice president of engineering services at Red Hat, which bought embedded OS vendor Cygnus last January. "That's the Holy Grail of the exercise. We believe it's quite doable today." Red Hat is working toward application portability between Red Hat Linux and its embedded OSes with its EL/IX program. EL/IX defines APIs at four graduated layers of functionality, from a minimal set of interfaces to a full Linux API. One layer has been completed so far, Knuttila said.
Industry agreement
The Embedded Linux Consortium (ELC) hopes to do the same thing for every embedded Linux distribution out there. By establishing a reference platform for embedded Linux, the 125 members of the ELC hope to spur development on the open source platform and simplify porting issues between platforms. It also hopes to get the attention of software vendors like Apple to provide missing tools for supporting QuickTime movies on devices. The specification will borrow from the POSIX 1003.13 PSE 52 and PSE 53, the single UNIX Specification, and the Linux Standard Base. It will undergo a rigorous review process online before being adopted, hopefully by summer. And once it's adopted, vendors will be able to develop a whole new generation of tools to help developers build applications in compliance with the spec. The group is also at work on a testing suite to validate compliance with the reference platform, and a testing and certification program. Those pieces should be in place by the end of the year, said ELC's Singh. "Embedded Linux has been held back by not having any formal quality testing," Singh said. To get from fringe OS to dominant player requires one other thing: manpower. So far, the number of embedded Linux developers has been a little low to staff an open source micro-revolution. "Students are coming out of college with some abilities to program Linux," said John "maddog" Hall, executive director of Linux International, at the ELC meeting. "They know enough to be sys admins. But there is a serious shortfall of those that can actually program Linux, and there are very few that can do the work at the kernel level." So let's get to it.
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About the author | | | Judy DeMocker is a freelance computer journalist based in San Francisco. She is also a principal at marketing consulting and media training agency, DeMonster Communications. She can be reached at
jdemocker@sprynet.com. |
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