Linus Torvalds releases Linux 6.6 after running out of excuses for further work

After a typically calm development process, Linus Torvalds has given the world a new cut of the Linux kernel – version 6.6 to be precise.

The penguin emperor last week worried that release candidate 7 was "certainly on the bigger side of our rc7 releases in the 6.x series" and "bigger than I'd have liked it to be" – but also free of "issues that would be showstoppers."

Torvalds suggested a "quiet and normal" week of kernel coding would see him release a full version on Sunday US time.

His worries proved unfounded.

"So this last week has been pretty calm, and I have absolutely no excuses to delay the v6.6 release any more, so here it is," Torvalds wrote early on Monday morning, as version 6.6 debuted as planned.

Among the highlights of the release are the KSMBD in-kernel server for the SMB networking protocol, which adds additional features for sharing files and improving inter-process communication in Linux, hopefully speeding I/O.

Intel's Shadow Stack tech – designed to prevent return-oriented programming attacks – has made it into the kernel. The tech protects AMD CPUs, too. Speaking of AMD, early tests by the Linux-lovers at Phoronix found substantial performance gains for its manycore "Bergamo" CPUs thanks to the inclusion of the Earliest Eligible Virtual Deadline First (EEVDF) scheduler. Intel CPUs enjoyed the scheduler, too.

The kernel also added support for AMD's Dynamic Boost Control tech that allows users to tune Ryzen CPUs for optimal performance. This should help some Lenovo laptops that ship with Linux.

The KVM hypervisor gained more support for RISC-V guests, HP laptops gained a driver that allows BIOS tweaks to be made from Linux, while further temperature and voltage sensor support for desktop motherboards debuted.

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An oddity in this cut of the kernel is the removal of references to the United States National Security Agency (NSA), which long ago developed the Security-Enhanced Linux (SELinux) module – referred to as "NSA SELinux" in help text and comments. A change to this cut of the kernel rebrands it as just "SELinux" – a reaction to the Agency's role in ops that have harmed privacy, per Edward Snowden.

Linux 6.6 will probably become this year's long-term support release – status that's been made unusually contentious by the recent decision to shrink support from six to two years.

Torvalds, as always, opened the merge window for the next version of the kernel. This has been a very calm year for kernel development, with five releases out the door in 2023 with very little incident.

Linux 6.7 may foreseeably be a little more complicated, as Torvalds advised he'll be travelling this week, which usually reduces his productivity a little. The timing of this push may also complicate matters, as a typical schedule of seven release candidates will see the first land just six weeks before Christmas. US-based contributors will also have a Thanksgiving-sized hole kicked in their schedules, making it possible work on this release will be slow and Torvalds could push it into early 2024. ®