Nearly 100 developers and programmers attended the grass-roots Real Time Linux Workshop here last week, and all but one voted to proceed with the use of EL/IX as their API.

At the heart of the workshop was the perceived need to prevent real-time Linux efforts from fragmenting. Given Linux's open-source nature and the sudden surge in embedded systems using the OS, some developers are worried that incompatible versions of the OS might crop up.

"You could call it going on the offensive," said Phil Wilshire, a programmer based in Spokane, Wash. who attended the workshop.

Developers also showed off their real-time Linux projects, which ranged from esoteric telescope-aligning systems to a Philips audio player.

Linux has a double handicap as a real-time OS: It wasn't designed for real-time responses, and it's too large in raw form to be an embedded OS. During the past two years, a flurry of projects has emerged to shrink Linux down to embedded size and/or adapt it to real-time environments.

The effort to build a real-time Linux meant adding a kernel atop the Linux kernel itself, specifically to handle interrupts and to preempt the typical latency of the Linux kernel.

Wilshire noted that two such efforts have blossomed recently — one out of New Mexico, and another from a team in Italy — but each group had to write its own Linux API.

Among the workshop's goals was to select one API for future real-time Linux efforts, hoping to preempt any fragmentation of the OS. But attendees were happy with presentations by representatives from Cygnus (Sunnyvale, Calif.), and gravitated toward EL/IX as the basis for such an API.

"When we heard the aims and direction that EL/IX is taking, we decided we might as well get together with these guys," Wilshire said. "What I would call it is a strategic alliance."

The goal is to come up with a "fully conformant, industrial API," Wilshire said. The New Mexico team's API looks like a good basis for a simple API, one for dabblers who want to get started on real-time Linux development in a couple of hours. But for an "industrial" API, EL/IX appears to be a good base, Wilshire said, although he and other workshop attendees now have to go through the work of digging into the EL/IX specifications to see where they might want to suggest changes.

One for all

The open-source nature of Linux development means the kernel can be altered by developers. The goal of a common API — and Cygnus' stated goal when it introduced EL/IX last September — is to prevent fragmentation of embedded Linux into incompatible versions, as a common API would ensure that applications built for one kernel could run on another.

"Linux, being open-source, lends itself to being adopted very easily," said Rick Lehrbaum, publisher of Linuxdevices.com, a Linux-focused Web site. "Whoever had a specialty was adapting it to that specialty."

Cygnus said that its EL/IX can provide a grounding point of compatibility for all embedded varieties of Linux. The API also is a linking point between Linux and eCos, Cygnus' own real-time operating system.

When attendees were asked to vote on the API issue on the last day of the conference last Wednesday (Dec. 15), all but one of the attendees cast their lot with EL/IX, according to reports from Cygnus attendees. The one dissenter held that the group should wait to see if any other APIs were being developed within the larger framework of the Posix operating environment, of which EL/IX is a subset.

Indeed, Lynx Real-Time Systems Inc. (San Jose, Calif.), as part of its plunge into the Linux realm, is developing a similar API which will allow Linux application binaries to run on the upcoming 4.0 version of its LynxOS real-time operating system. Lynx was not present at the workshop but would be welcome to participate in the group, Wilshire said.

Overall, Cygnus cofounder Michael Tiemann said reports from the event were positive towards EL/IX.

"From a market perspective, from a high-level technology perspective, from a detailed API perspective — EL/IX has passed all three tests," Tiemann said.

One advantage attendees liked was flexibility. EL/IX is still open to revisions, which workshop attendees felt gave them the opportunity to tailor the API to meet their needs.

"We like EL/IX as an opportunity to take what we made out of Posix and still come out with some kind of standard," Wilshire said.

One advantage EL/IX might have, Tiemann added, is the backing of the Red Hat Inc. brand name, as that company is in the process of acquiring Cygnus.

Just less than 100 attended the Real Time Linux Workshop, and about 20 or 30 of them came from the United States, by informal counts. Attendees included representatives of major European electronics companies such as Philips, Alcatel and Siemens AG.

Wilshire said he was pleased with the atmosphere of the conference and has high hopes for the API effort.

"People who are going to look over this API are not the disinterested industry powers who've got another gong to bang, but people like me who are in the trenches," he said.

In addition to casting support for EL/IX, workshop attendees created seven teams to work on different aspects of embedded Linux standards, including one team to pursue using EL/IX as a common API. Another of the teams will draft a real-time patch for the Linux kernel and submit it to Linus Torvalds, Linux's creator and final arbiter of what goes into the kernel.

"We're going to pull out a patch to Linus and keep doing it until we get it right," Wilshire said.