Today, Linus Torvalds announced the official release of Linux Kernel 6.15, introducing an array of new features and enhancements aimed at improving hardware support and overall system performance.
Key highlights of Linux 6.15 include the introduction of Rust support for the hrtimer and ARMv7 architectures. A new boot parameter, setcpuid=, has been added for x86 CPUs, along with enhanced support for sched_ext to accurately count and report internal events. Improvements have been made to x86 Intel and AMD PMUs (Performance Monitoring Units), as well as nested virtualization support for VGICv3 on ARM and the emulation of FEAT_PMUv3 for Apple Silicon devices.
Additionally, the Linux kernel now features a new API to gather information regarding the mount and unmount events of filesystems. Hardware encryption improvements include support for hardware-wrapped encryption keys within the block layer, and the EROFS filesystem now supports 48-bit block addressing. A novel security hook for the io_uring subsystem provides security modules more control over permissions.
The FUSE filesystem has been updated to handle filenames exceeding 1,024 characters. Furthermore, the perf subsystem now offers latency profiling capabilities using scheduler information, while the BPF (Berkeley Packet Filter) subsystem has improved program verification, especially for those containing loops. OverlayFS also sees a new override_creds mount option, which adjusts the credentials used for accessing lower filesystem layers.
Support for new extensions within the RISC-V architecture has been added, including the BFloat16 floating-point extension and several new features for zoned devices and the XFS filesystem. Linux 6.15 has also enhanced network capabilities with a new TCP socket option (TCP_RTO_MAX_MS) to set maximum retransmit intervals on IPv4 connections and introduced new BPF callbacks for networking tasks.
Expect significant advancements in hardware support with new and updated drivers for devices like the Apple Touch Bar, Google Pixel Pro 6, MYIR Remi Pi development board, and various HP laptops with CS35L41 HDA audio chips. Updates to the ACPI fan and button drivers enhance system event notifications, critical for waking systems from sleep.
Noteworthy changes also include the removal of support for 32-bit (x86) systems that exceed eight CPUs or 4GB of RAM and the addition of a new auditing mechanism for the Landlock security module to clarify access denials. A new fwctl subsystem allows user space to securely carry out Remote Procedure Calls (RPCs) within device firmware, while kernel hardening features have been introduced to seal memory mappings against changes, albeit disabled by default due to potential application issues.
Linux Kernel 6.15 is now available for download from Linus Torvalds’ git tree and the kernel.org site for those interested in compiling it on their system. It is recommended, however, to wait for the kernel update to be included in your distribution’s stable software repositories before proceeding with any updates.
As the release of Linux Kernel 6.15 marks a significant point in development, the merge window for the upcoming Linux Kernel 6.16 will open shortly, with expectations set for a first Release Candidate by June 8, 2025.