Linux Kernel 6.9

Linus Torvalds has released version 6.9 of the Linux Kernel. The kernel is the heart of the operating system and, simply put, sits as a layer between the hardware and the applications. In this release we find support for Rust on AArch64 CPUs and there is a new dm-vdo. More information can be found at 9to5Linux. Below you will find an overview of the most important changes and improvements in this release, compiled by OMG Ubuntu.

Overview of Linux 6.9 Features

Linux kernel 6.9 includes the usual glut of enablement work for upcoming hardware and hardware-related features that most of us aren't currently able to take advantage of. But there is plenty of stuff that is more relevant. Linux 6.9 debuts AMD P-State 'preferred core' support in the AMD P-State driver for AMD Zen 2 and later chips.

Preferred cores reach a higher maximum frequency than other cores, and this kernel support allows Linux scheduler to pass high priority tasks to those cores specifically. Also included is Intel Fastboot support which, as the name implies, hastens boot speeds. How? By reducing (and in some cases skipping) mode sets not required during boot. Previously enabled for “Skylake” and above, Linux 6.9 brings this feature to older chipsets.

For several years kernel devs have been working on a big update to CPU timer code, which organizes, schedules, and enforces the timing of tasks and processes — in Linux 6.9 it arrives! Additionally, Linux 6.9 sees “significant and invasive” changes to its workqueue code, primarily to address some issues introduced by an earlier change in Linux kernel 6.6. A handful of tweaks to improve CPU isolation also feature.

The Linux kernel virtualization module KVM sees a clutch of assorted improvements, including performance gains in emulated event triggering and during 'forced immediate exit' scenarios. Performance improvements to case-insensitive file and folder handling in EXT4 (and other file systems that use it) is present, with kernel now said to be “trying a case-sensitive comparison first and then fallback to case-insensitive lookup if that fails” .

Linux kernel 6.9 also nukes a hardware vulnerability in Intel Atom CPUs (remember those?) which “may allow a malicious actor to infer data values ​​previously used in floating point registers, vector registers, or integer register.” Device-specific buffs include battery charge control for Fujitsu laptops, and a substantial performance boost on the HP Omen 17 laptop, despite with significantly larger power draw and heat generation — don't worry; it's optional.

There's also support for the Lenovo IdeaPad 'refresh rate' key (which you'll be shocked to hear us used to change display refresh rate); fan speed control for Microsoft Surface laptops, and the Lenovo ThinkPad ACPI driver now works with more Fn keys. Linux 6.9 supports scores of Samsung wireless devices out-of-the-box, including an unspecified wireless keyboard, the (thicc looking) Gamepad controller, the (cute) S Action Mouse, and the Galaxy Book Cover and HOGP keyboard combo.

Linux gamer with an Xbox controller fetish? You'll be thrilled to hear that two of most popular (and pretty decent, I hear) 3rd-party Xbox controllers work in Linux kernel 6.9 through the Xpad driver: the Snakebyte GAMEPAD BASE X and GAMEPAD RGB related improvements are onboard, including Rust language support on 64-bit ARM processors; support for running in LPA2 mode; and improved performance thanks to better translation lookaside buffer (TLB) usage.

Other notable changes in Linux 6.9:

• Power efficiency tweaks for Intel Meteor Lake
• Kernel energy model supports run-time updating
• Access to GCC named address spaces
• Larger fonts in frame-buffer console
• Better memory bandwidth throttling
• Btrfs throughput increase + other fixes
• Cirrus HD audio codec supports more devices
• Energy Efficient Ethernet adds 2.5GE and 5GE link modes
• Realtek RTW88 Wi-Fi driver supports rtw8811cu & rtw8821cu
• FUSE passthrough support
• EXT2 filesystem now deprecated
• AMD FreeSync removed

Obviously there's a lot more to this release than the hand-picked highlights above, including a flurry of security fixes, scores of finessing to various filesystem finessing, a fleet of effort to further Linux's support for RISC-V, LoongArch, SPARC, et al.