The Linux operating system has turned the market for server operating systems on its head. The systems that act as web servers or Internet gateways have been especially affected. Will the same thing happen in the embedded system arena?
Several embedded vendors think so. Caldera, one of the first Linux distribution vendors, recently split into two separate companies. One of them, Lineo, is devoted to adapting Linux to embedded systems. In 1999, veteran RTOS architect Jim Ready founded MontaVista, which seeks to develop and promote an embedded Linux.
Then there's the recent acquisition of Cygnus Solutions by Linux distributor Red Hat. This move demonstrates that the Linux community generally looks at embedded systems as a natural evolution for the OS. More evidence of this attitude can be found in Linus Torvald, who originated the Linux kernel as a graduate student. He's now a principal at Transmeta, the startup that's designing a new processor architecture for embedded devices running Linux.
As a key component of the Open Source movement, Linux is distributed under the GNU Public License, or GPL. The GPL essentially states that if you receive software distributed under this license, you can modify it and further distribute it. That is, you can give it away or sell it, but only if you give the recipients the same rights that you received. This means that distributors typically provide customers with source code along with the executable programs, since the distributors themselves received source-code rights.
Real-time operations still elude most implementations of embedded Linux, however. An RT-Linux has been developed at the New Mexico Institute of Technology, but it accomplishes this feat by running a real-time executive beneath the traditional Linux OS. In a manner similar to that used by VentureCom with Windows NT, RT-Linux utilizes a small, hard real-time kernel and standard Linux. That way, the system can be used for applications like data acquisition, control, and robotics, while still serving as a standard Linux workstation.
Linux remains likely to be a popular embedded-system OS in the future, because design engineers can take its functional and reliable code base and adapt it to just about any purpose. It's a happy medium between buying a commercial RTOS, which is reliable but an imperfect fit to the project, and writing and maintaining a proprietary RTOS that fits the bill but requires more development resources than any one project can justify.
Embedded Linux is years away from becoming a mainstream solution. MontaVista has added features to its Hard Hat Linux for headless operation, flash-file system support, and other expected features. But it will take time for engineers to evaluate Linux for their products, perform the needed development work, and start shipping products.
There's no doubt that embedded systems will continue to firmly establish themselves as a legitimate and perhaps natural target of mainstream Linux. Meanwhile, the Linux community seems to be saying that there's no difference between enterprise information systems and embedded systems. That seems like a smart way to go.