Linux 4.0 Is All About Stability (Also: Reboot-Free Updates)

Linux 4.0 made its official debut this week. Spoiler alert: The version number in this newest latest iteration of the open source operating system kernel doesn’t mean it’s actually four times better than version 1.0—or, for that matter, twice as good as the 2.x series, which was the longest-running in Linux’s history. But it is a tight, stable release, according to developer Linus Torvalds.

Torvalds announced the 4.0 release April 12. “Linux 4.0 was a pretty small release,” he wrote, but added that that “is all good,” since “‘v4.0 is supposed to be a _stable_ release,’ and very much not about new experimental features etc.”

That doesn’t mean there’s nothing new. The 4.0 kernel introduces some features that will appeal to open source users, chief among them live-kernel matching, which makes it possible to update the kernel without having to reboot the system.

That functionality has been available from third-party projects such as Red Hat‘s kpatch and Oracle‘s Ksplice for years. But it will henceforth come bricked into the kernel itself. For now, the feature takes some know-how to configure properly, but this is another point in Linux’s favor within the enterprise, where knowing you never have to reboot your servers is always a good feeling.

Other updates in Linux 4.0 include hardware-specific tweaks for various devices including CPUs, storage drives and video cards, as well as enhancements to file storage systems.

Still, stability is the headline word in this new release, Torvalds wrote. “Feature-wise, 4.0 doesn’t have all that much special. Much have been made of the new kernel patching infrastructure, but realistically, that not only wasn’t the reason for the version number change, we’ve had much bigger changes in other versions. So this is very much a ‘solid code progress’ release.”