Opposition to a new version of the licence for open source OS Linux is growing, with a number of prominent developers joining originator Linus Torvalds in criticising changes in wording.

A number of Linux kernel developers have signed a "position paper" on General Public Licence (GPL) version 3, which is intended as the successor to the most popular open source licence. The developers warned the new licence, and the Free Software Foundation's plans to actively use and promote it, have "the potential to inflict massive collateral damage upon our entire ecosystem and jeopardise the very utility and survival of open source."

Separately, an informal survey of Linux kernel developers, covering a slightly different set of individuals, found that none of those polled supported the new GPL, while most actively opposed it.

The position paper was signed by well-known figures in the Linux world, such as Andrew Morton, James E.J. Bottomley, Thomas Gleixner and Greg Kroah-Hartman, but not by Linus Torvalds. However, in the survey Torvalds registered his position as somewhere between "I think v3 is much worse than v2" and "I really dislike it."

The position paper argues that an imperfect GPLv3 is worse than nothing, because it would contribute to the profusion of open source licences and could balkanise the open source software world. "We regard reducing the open source licensing profusion as a primary objective," the paper says.

Therefore, any revision to the GPL should be strong enough that most projects using v2 would want to immediately migrate, but v3 doesn't meet this standard, the paper says. That's due to several problems, including "use restrictions" designed to combat copyright management measures, and the fact that it appears it could "jeopardise the entire patent portfolio of a company simply by the act of placing a GPLv3 licensed program on their website."

Because the FSF is planning to shift its projects to v3 and "pressure" other GPL-licensed projects to move, "we foresee the release of GPLv3 portends the balkanisation of the entire open source universe on which we rely," the developers wrote. "We can only assume the FSF is unaware of the current potential for disaster of the course on which it has embarked," the paper says.

The developers concluded that they "cannot see any drafts of GPLv3 coming out of the current drafting process that would prove acceptable to us." The informal survey, carried out via the Linux kernel development mailing list, covered a similar but slightly broader group of 29 Linux kernel contributors. While four registered only mild opposition to v3, none were neutral, none said they favoured the new licence and several said they "really dislike" it.

The FSF on Monday responded to the developers' concerns, saying many of their perceptions were inaccurate. John Sullivan, a programme administrator for the FSF in Boston, said in a statement that the FSF had no power to force v2 users to migrate to v3. He said the anti-copy protection measures in the current draft of v3 aren't "use restrictions" but distribution restrictions, a significant difference.

"Contrary to what some haved said, the GPLv3 draft has no use restrictions, and the final version won't either," he stated. "It doesn't restrict how they, or you, can run the program; it doesn't restrict what they, or you, can make the program do. Rather it ensures you, as a user, are as free as they are."

The FSF said the draft doesn't endanger a company's entire patent portfolio. Rather, v3's patent licence covers only patents implemented by a program that the company distributes. Version 2 doesn't include an explicit patent licence.

Those supporting a revision of the GPL point to a number of shortcomings that have come to light in recent years. Pamela Jones, editor of Groklaw, recently pointed out on the site that GPLv2 "is not compatible with the Apache licence. It doesn't cover Bitstream. It is ambiguous about Web downloads. It allows TiVo to forbid modification. It has no patent protection clause. It isn't internationally useful everywhere, due to not matching the terms of art used elsewhere. It has no DMCA workaround or solution. It is silent about DRM (digital rights management)."

Those backing the current GPL say those omissions are part of what has made it work so well. "I see it as a huge advantage," Torvalds wrote on Groklaw. "The GPLv2 covers the only thing that really matters and the only thing that everybody can agree on." That boils down, he wrote, to "give all source back... give back in kind."