Linux creator Linus Torvalds remains sceptical about the upcoming third version of the General Public Licence (GPLv3).

"I still think GPLv2 is simply the better licence," Torvalds wrote in a posting to the Linux Kernel Developer mailing list on Sunday.

Torvalds oversees contributions to the Linux kernel and can decide to change the licence.

The kernel forms the core of the operating system, but Linux distributions contain code from many other open source projects, most of which are governed by the GPL.

Each of those projects has to decide whether they want to switch to GPLv3 or remain on GPLv2.

Torvalds has softened his disapproval of the forthcoming licence in recent months, but still has his doubts.

"I was impressed in the sense that it was a hell of a lot better than the
disaster that were the earlier drafts," he said.

The Linux founder has previously dismissed the licence as "religious". He disagrees with its attempts to prevent the use of digital rights management and its efforts to undermine the Novell-Microsoft partnership.

He also killed speculation that the Linux kernel would use a dual licence, allowing users and distributors to choose between GPLv2 and GPLv3, describing it as "unlikely and technically quite hard" but at least "possible in theory".

No major open source projects have yet lined up behind the GPLv3. Sun Microsystems has been one of its most vocal supporters so far, suggesting that it might choose the licence for its Solaris operating system.

But the company has made it very clear that it will not make a decision on the matter before the final version of the licence has been published.

If Sun did pick GPLv3 for Solaris, it would make it more appealing for the Linux kernel to follow suit.

With both projects under the same licence, developers could more easily swap technologies, for instance brining over the Solaris ZFS file system or DTrace, an application performance optimisation tool.

"I don't think the GPLv3 is as good a licence as v2, but on the other hand, I'm pragmatic, and if we can avoid having two kernels with two different licences and the friction that causes, I at least see the reason for GPLv3," Torvalds commented in another posting in which he responded to the possibility of Solaris under GPLv3.

"As it is, I don't really see a reason at all [to adopt GPLv3 for the Linux kernel]."

The GPLv3 is currently in the "final call" draft stage. The final version is scheduled for publication by the end of this month.

The GPL is one of 58 offically approved open source licences. An estimated 80 per cent of all open source projects are governed by the GPL.