Free Software Foundation Targets RTLinux for GPL Violations

The Free Software Foundation on Friday took aim at RTLinux and FSMLabs, the company that distributes it, claiming that FSMLabs has used a patent license to violate the GNU General Public License.

The issue revolves around an FSMLabs patent for real-time interrupt handling using a software emulation layer for interrupt masking, so that interrupts can be prioritized. The Free Software Foundation claims that Victor Yodaiken, the CEO at FSMLabs, has used the patent to impose restricted terms on distribution of this program.

"Yodaiken has attempted to use the patent to impose restrictive terms on a GPL-covered program [Linux, the kernel used in the GNU/Linux operating system]. These terms conflict with the GNU General Public License, and imposing them is a violation of the GPL," Foundation spokesman Bradley Kuhn told eWEEK. "We have told Yodaiken this, and we have told him what license terms would comply with GPL. He, like everyone, has the responsibility to comply with the GPL or cease his infringing distribution. Anyone else redistributing a modified version of Linux under the restrictive patent license that Yodaiken uses will also be violating the GPL," Kuhn said.

"[It is] a shame that Victor Yodaiken has chosen to obtain a patent for an idea that we believe should not be, and is not, patentable. We have held extensive discussions with him in this regard, but he has refused to remove those conditions of the patent that impose restrictive terms on the redistribution of the program and which are not permitted by the GPL," Kuhn said.

As such, the Foundation had no alternative but to take the matter public, Kuhn said. In nearly all of the cases of GPL violations, the Foundation was able to successfully negotiate with the offender and achieve compliance with the GPL. "That was sadly not the case here," he said.

FSMLabs Yodaiken could not be reached for comment, but the companys Web site states that the "use of RTLinux is governed by a patent license."

The RTLinux Web site describes the product as "a hard real-time operating system that handles time-critical tasks and runs Linux as its lowest priority execution thread. In RTLinux, a small hard real-time kernel shares one or more processors with standard Linux. This allows the system to run accurately timed applications to perform data acquisition, systems control and robotics, while still serving as a standard Linux workstation."

Kuhn also said the Foundation opposes the policy of software patents as these are "a harmful government policy of creating monopolies that restrict computer users."

But the thorny issue that now remains is who exactly will enforce this alleged breach of the GPL license. "[It is] up to the copyright holders of Linux -- a long list which includes Linus Torvalds and Allan Cox -- to enforce the GNU GPL for their code," Kuhn said. "The FSF is not one of them; we have never been involved in developing Linux, the kernel. The FSF holds the copyright for a number of other major components of the GNU/Linux operating system, but those programs are not involved in this issue. So the FSF is not a party to this issue in a legal sense."

While he was unsure if any of the copyright holders intend to take legal action, Kuhn warned that if Yodaiken remains in violation of the GPL, the Foundation "may well choose to support any efforts by other companies to invalidate Yodaikens patent in the courts, and we may also support actions taken by others to uphold the GPL."

This is not the first time the free software and open-source communities have voiced concerns about patent violations. Members of the open-source community recently expressed their concern about ongoing moves by Microsoft Corp. to acquire a range of software patents that the company can potentially use to attack and restrict the development and distribution of open-source software.

Microsoft executives have, in turn, repeatedly criticized the use of the GPL over the past few months. Steve Ballmer, Microsofts chief operating officer, recently described Linux as a "cancer that attaches itself in an intellectual property sense to everything it touches. Thats the way the [GPL] license works," he said. His comments followed similar scathing attacks by senior vice presidents Craig Mundie and Jim Allchin.