The first major Linux kernel version number change since 2003 is now available, but it's not as big a change as the number change might imply.
The Linux 2.6 kernel was first released in December of 2003 and has since been followed by 39 major releases, the last being the 2.6.39 kernel that came out in May. Linux founder Linus Torvalds decided that going to 2.6.40 was too big a number and instead pushed the version number to 3.0.
"There are no special landmark features or incompatibilities related to the version number change, it's simply a way to drop an inconvenient numbering system in honor of twenty years of Linux," Torvalds wrote in a mailing list posting.
The numbering change to 3.0 also is not expected to have an impact on integration with other open source Linux stack components. In some open source projects, the move to a larger version number implies a binary compatibility change but that's not the case with Linux 3.0.
"The kernel version numbering is not very impactful from a release integration perspective," Tim Burke, vice president of engineering, Platform Business Unit at Red Hat told InternetNews.com. "Recall that Linus reiterated this was just a number change, not a major functional change."
Though there is not a major functional change in Linux 3.0 there are some new features. One key feature that at long last has landed in the mainline kernel is the Xen hypervisor, after several years of delay and debate. The rival KVM hypervisor has been included in Linux since the 2.6.20 kernel release in 2007.
"Xen is better integrated into the mainstream kernel and this does benefit all users of Xen in the sense of better harnessing the power of community," Tim Burke, vice president of engineering, Platform Business Unit at Red Hat told InternetNews.com.
Red Hat supports Xen in Red Hat Enterprise Linux 5.x operating system, and not in the newer 6.x branch, as Red Hat has shifted its focus to KVM. Red Hat Enterprise Linux 6 (RHEL) debuted in November of 2010. Red Hat continues to update RHEL 5.x and just released RHEL 5.7 this week.
"Over the past several years, the most active participants in upstream Linux development have realized that the more integrated approach of KVM is the most efficient path to ongoing virtualization development," Burke said. "By not having to duplicate lots of low-level hardware enablement, as well as being able to utilize other generic system services (such as SELinux and cgroups), the KVM implementation has proven superior."
Another key area of improvement comes in the Btrfs filesystem. Btrfs is a next generation Linux filesystem and has been in active development since 2008. Btrfs has been proposed to become the default file system in Fedora 16.
"To achieve this, the developers have put some very high quality, performance and feature goals in place," Burke said. "This work is progressing very well with most of the features being collected into the Linux 3.0 release kernel."
Burke added that Red Hat developers are some of the leaders in the work done on btrfs for Linux 3.0.
Moving forward, the Linux 3.0 kernel will also represent a change in incremental kernel release version numbers. The next major Linux kernel release will be numbered 3.1, while stability and bug update releases will be numbered as 3.0.x.
"The stable team will take the third digit, so 3.0.1 will be the first stable release based on 3.0," Torvalds said.