A new version of the Linux kernel has been released, adding support for virtualization and showcasing the use of a new release-management tool developed by Linux inventor Linus Torvalds himself.

Availability of the new release, dubbed version 2.6.11.12, was announced Sunday in an e-mail posted to an Internet mailing list by Chris Wright, a member of the so-called "stable team" responsible for the kernel. The 2.6.11.12 kernel is expected to wend its way into full-blown distributions of Linux available from major vendors in the latter half of the year.

"It's a significant release," said Bill Weinberg, architecture specialist at the Open Source Development Labs, the Beaverton, Ore.-based Linux consortium. "What makes it important are two things: the inclusion of Xen, and the fact that it's built on the new release management tool, called Git, that Linus put together the last couple of months with some other people." ("Git" doesn't stand for anything in particular, Weinberg added.)[Update: On Wednesday, Bill Weinberg said that, contrary to his earlier information, Xen is not yet integrated into the new 2.6.11.12 kernel, however, developers hope to merge the Xen patch late this summer.]

Most previous versions of the kernel relied on a program called Bitkeeper to keep track of code and related patches. However, earlier this year BitMover, the supplier of the program, decided to stop supplying the program for free to the Linux kernel developers, citing support costs. Torvalds subsequently began work on Git.

"When Linus began developing Git, there were fears, in the press and in industry, that it would slow down the release cycle," explained Weinberg, noting that there were concerns in some quarters that work on Git would distract Torvalds from his core job of overseeing kernel releases. "So to some degree this release is a proof point that it did not slow them down, even if they did have to learn to use a new tool while they were debugging [the kernel]," Weinberg said.

For users of the kernel, the more interesting feature may be the addition of Xen, which is a virtual machine monitor, which enables multiple operating system images to execute concurrently on the same platform. Xen is included with the 2.6.11.12 kernel as a standard configuration option, meaning it doesn't have to be added in manually via a cumbersome series of packages and patches.

"It's sign of the maturity of the Linux kernel and the Linux operating system that virtualization is now a mainstream capability and not something added in," Weinberg said. "What's been added to the kernel is the hypervisor, which allows you to invoke and run virtualized operating systems on top of Linux. It's not that there are multiple OSes being included in the box or anything, it's the infrastructure for running Xen."

The new 2.6.11.12 release can be downloaded for free from kernel.org, which serves as the Linux kernel archive site.