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The Linux Kernel on a Dual Basis?

One solution to the debate about whether the Linux kernel should migrate to the almost-complete GPL version 3 is to have the Linux kernel dual-licensed under GPL versions 2 and 3.

Linux kernel developers are discussing the solution as a potential option for dealing with the new open source license.

GPL version 3 has been under discussion since early 2006 and is expected to be finalized on June 29. The new GPL includes provisions for Digital Rights Management (DRM) and patents, as well as new clauses that make the GPL friendlier to other open source licenses, including the Apache 2 license.

Linus Torvalds, who in the past has come out against GPL version 3, isn't exactly enthusiastic about a dual-licensed kernel, either. Linux is currently licensed under GPL version 2.

"I don't think the GPLv3 is as good a license as v2, but on the other hand, I'm pragmatic, and if we can avoid having two kernels with two different licenses and the friction that causes, I at least see the _reason_ for GPLv3," Torvalds wrote in a mailing-list posting.

"As it is, I don't really see a reason at all. I personally doubt it will happen, but hey, I didn't really expect them [Sun] to open-source Java either, so it's not like I'm infallible in my predictions."

Richard Stallman, founder of the Free Software Foundation, which is overseeing the GPL version 3 process, has said that the GPL version 2 won't necessarily be compatible with version 3.

Incompatible licenses working together in Linux, however, isn't uncommon, as the GPL version 2 isn't compatible with Apache License 2 though applications licensed under both schemes tend to be including together in Linux distributions.

Moving to GPL version 3 would be disruptive and could require patent grants, as well as restricting the use of Linux in consumer devices (like Tivo) that include DRM technologies. GPL version 3 explicitly restricts the use of GPLv3-licensed applications where DRM restricts users' freedoms.

"I consider dual-licensing unlikely (and technically quite hard), but at least _possible_ in theory," Torvalds wrote. "I have yet to see any actual *reasons* for licensing under the GPLv3, though."

Torvalds noted the Novell Microsoft deal on interoperability and patent covenants isn't reason enough to migrate to GPL version 3. The new GPL includes provisions intended to prevent third-party patent deals of the type that Novell and Microsoft have.

"The argument seems to not so much be about the Novell deal, as about an excuse to push the GPLv3," Torvalds wrote.