The second Linux kernel of 2009 is now out, sporting a long list of improvements — and at least one regression.
New filesystem support, security and driver improvements are all part of the new Linux 2.6.30 kernel release, although one of the most noticeable elements in the new release is the kernel inclusion of fastboot, an enhancement designed to speed startup for Linux-based systems.
Linux 2.6.30 also marks a step back, reinaugurating Tux the penguin as its official mascot after a one-release hiatus, during which Tuz the Tasmanian devil held the reins as a effort to raise awareness around the plight of the Tasmanian devil.
“I’m sure we’ve missed something, and I know we have some regressions pending,” Linux creator Linus Torvalds said in his mailing list announcement for the new kernel. “At the same time, we do need the coverage of a real release, and on the whole it looks pretty good.”
The release follows the 2.6.29 release by just under three months, and the features included in 2.6.30 will end up in the next round of Linux distributions as they face off against Windows 7 later this year.
Fastboot’s inclusion in the kernel is one of the release’s key elements, providing a mechanism for faster startup times within the mainline kernel itself. That’s a something of a new approach, considering that Linux distributions have already been implementing their own approaches for faster startup times. The Ubuntu Jaunty release, for example, claims a 25-second boot time while Red Hat’s Fedora 11 claims a 20-second boot time.
According to Red Hat, there is a difference between the aims and process of the new mainline Linux kernel’s fastboot — which was contributed to the community by Intel — and the approach to faster startups taken in Fedora 11.
“They’re solving a different set of problems,” Fedora kernel maintainer Dave Jones told InternetNews.com. “The Fedora work has been almost entirely done by improving init scripts in userspace, and by making applications more intelligent about the I/O they are doing.”
Jones adds that the fastboot patches are valuable, but there larger problems remain in userspace that can be addressed in Fedora.
Another key addition in the 2.6.30 Linux kernel release is Ftrace, a framework for tracing system calls.
“The Ftrace tracing infrastructure should make debugging certain problems easier,” Jones explained. “Previously, we would need to recompile the kernel with debugging patches added. Now, we have the ability to turn on certain types of profiling dynamically at runtime.”
Security also gets a boost in the kernel with the addition of the Tomoyo framework, which offers an alternate approach to SELinux (which stands for “security enhanced Linux”). Tomoyo, like SELinux is an access-control solution. According to the Tomoyo project site, the most distinguishable feature of Tomoyo Linux is its real-time policy learning feature.
Whereas SELinux operates in either permissive or enforcing modes, Tomoyo Linux also has a third mode — learning mode — in which it “generates definitions of domains and ACL (access control lists) for each domain … automatically,” according to the project site. “This policy-learning functionality covers from the system boot to shutdown.”
Tomoyo is a project that had been begun by Japan’s NTT, while SELinux is an effort that originally sprouted out of the U.S. government’s National Security Agency (NSA).
NTT also has another contribution that made it into the 2.6.30 with the NILFS2 filesystem (short for “New Implementation of a Log-structured File System”).
“NILFS is a new implementation of a log-structured file system (LFS) supporting continuous snapshotting,” according to the NILFS project site. “In addition to versioning capability of the entire filesystem, users can even restore files mistakenly overwritten or destroyed just a few seconds ago.”
There is also support in the 2.6.30 for a number of technologies that have not yet been finalized in standards. Linux 2.6.30 adds preliminary support for the under-development IEEE 802.11w standard for enhanced wireless security.
Preliminary support for NFS 4.1