Linux Kernel 3.0 Released

With Linux set to celebrate its 20th anniversary next month, what better time than now to usher in a new major version number? That was Linus Torvalds’ thoughts on things, and as a result of the micro version number for the 2.6 kernel becoming rather high (and somewhat comical), we’re now pushing forward and entering the Linux kernel 3.0 age, ending active development of the 2.6 kernel (excluding patches).

At the time of writing, the 3.0 kernel is found in the mainline repo, not the stable. That should come soon, however, and as per new versioning rules, while the mainline kernel will stick to a simple 3.x schema, the stable kernel will add a third digit, eg. 3.0.1. Despite this change, the inherent kernel versioning code is still three decimal places in the mainline variant (as pictured below).

As mentioned in our news section a couple of months ago, Linux 3.0, despite the version bump, is not what Linus considers to be a true major release. There’s nothing ground-breaking included in this release that sets it apart from other launches, a point he’s reiterated in a recent mailing-list post. But that’s not to say that there’s nothing interesting to talk about.

Btrfs, for example, has seen a significant upgrade, introducing automatic defragging and extents-level checksum validation. A fair complaint about Linux is that most of its file systems cannot be defragged, but Btfs aims to remedy that. In addition to an automatic mode (-o autodefrag), there’s long been the ability to manually defrag via the command-line, and also a method to avoid the copy-on-write algorithm that can lead to fragmentation over time. It’s important to note that Btrfs is still considered ‘experimental’, so at this point it’s recommended more for those who don’t mind getting their hands dirty. I’ve been running Btrfs on my notebook for about a month and haven’t encountered any problems so far, but I don’t think I’d risk it on my desktop at this point.

For Xen virtualization users, 3.0 finally introduces Dom0 (domain zero) support, allowing supported OSes far greater access to the host hardware, improving both performance and interoperability. For those who want to know what took this feature so long to become implemented, there’s an official blog post worth reading.

Other select changes include the ability to now mount Windows 2008 DFS shares via CIFS, the introduction of a wake-on-WLAN mode, and support for TRIM with the OCFS2 file system, and also support added for Microsoft’s Kinect and AMD’s Llano IGP and more. Overall, a great release. Not major, but still significant in many different ways.