Linux Kernel News Archives

Last week I wrote about Linux patches cleaning up x86 32-bit kernel builds for x86_64 CPUs. The new iteration of those patches were sent out today, including the addition of a patch adding the CONFIG_X86_64_NATIVE Kconfig tunable for enabling "-march=native" kernel builds to cater your optimized kernel compilation for the CPU on which you are building the kernel.

Currently the Linux kernel's "perf" performance monitoring subsystem has a limit on 2,048 CPU cores for its CPU map that is set by the MAX_NR_CPUS value. But that's becoming not enough in today's high core count era that patches are looking to raise it to a 4,096 CPU core limit by default.

Linus Torvalds just issued Linux 6.13-rc2 with an initial serving of bug/regression fixes following last week's Linux 6.13-rc1 release that capped off the feature-packed Linux 6.13 merge window.

The Linux kernel EFI Zboot code for carrying the Linux kernel image for EFI systems in compressed form is doing away with its "compression library museum" of offering Gzip, LZ4, LZMA, LZO, XZ, and Zstd compression options to instead just focus on Gzip and Zstd compression support.

Sent out this morning were the "x86/urgent" updates ahead of Linux 6.13-rc2 due out later today. There are x86 fixes for both Intel and AMD processors this week. Most notable though is fixing some buggy Intel Core Ultra "Lunar Lake" behavior that could lead to responsiveness/delay issues due to the MONITOR implementation being buggy/broken.

Following 107k lines of old driver code within the staging area of the kernel removed for Linux 6.13, over in the crypto space they are looking at some cleaning as well with plans raised to remove the Stream Processing Unit (SPU) driver for the old Sun Niagara 2, the Sun UltraSPARC T2 and this SPU was also found in the UltraSPARC T3 as well.

While the Linux v6.13 merge window has been over for less than one week, already the first pull requests of new feature code are being submitted to DRM-Next for queuing the display/graphics driver changes ahead of the Linux 6.14 merge window in two months.

It's been a while since there have been any new advancements or performance optimizations to talk about for Multi-Gen LRU (MGLRU) that was upstreamed to the Linux kernel two years ago as a very exciting kernel innovation. But that's changing now with some fresh performance optimizations being worked on for the MGLRU code.

Linux stable maintainer Greg Kroah-Hartman officially designated Linux 6.12 as this year's long-term support (LTS) kernel version.

With the new Linux kernel patches posted yesterday for cleaning up x86 32-bit kernels on x86_64 CPUs as part of that patch series was introducing new Kconfig build options around the x86_64 micro-architecture feature levels. It turns out though that Torvalds is completely against how the x86_64 feature levels are handled by the compiler toolchain folks and doesn't want to see it invading the kernel.

As we approach 2025, hopefully none of you are still running x86 32-bit kernels / 32-bit OS software on x86_64 processors, but should you still be into that, there are improvements on the way.

As expected, this evening Linus Torvalds released Linux 6.13-rc1 to cap-off the two-week Linux 6.13 merge window. With Linux 6.13 comes many new features.

NVIDIA engineer Yonatan Maman posted a set of "request for comments" patches this Sunday to implement GPU Direct RDMA "P2P DMA" for device private pages. This is the latest in the effort by multiple vendors to allow more efficient data sharing between GPUs/accelerators and other devices like network adapters.

Last night when writing about the Clang AutoFDO and Propeller optimization patches sent in for Linux 6.13 I had wondered whether Linus Torvalds would go through with the pull request given some of his past commentary around aggressive compiler optimizations... But to much delight, this evening Linus Torvalds has merged the Kbuild pull request that introduces Clang-based AutoFDO and Propeller compiler optimization support for allowing greater kernel performance out of tailored (profiled) workloads.

In addition to the USB updates and big staging flush merged yesterday for the Linux 6.13 kernel merge window, the "char/misc" pull was also honored for that catch-all of various kernel changes. With the char/misc pull there are some notable additions for those wanting to write kernel drivers within the Rust programming language.

Making for an even more exciting Black Friday is the Kbuild pull request submitted today for the near-over Linux 6.13 merge window... And it includes Clang Auto Feedback Directed Optimization (AutoFDO) support for kernel builds as well as Clang's Propeller.

Greg Kroah-Hartman is out today with all of the pull requests for Linux 6.13 of the areas of the kernel he oversees. Most notable with the updates on the staging side are clearing out several drivers seeing no real code activity and no apparent users of the mainline Linux kernel... As such the staging pull lightens the kernel by around 107k lines of code.

Open-source developer Rui Ueyama who is the lead developer of the Mold high performance linker and previously on the LLVM lld linker has written a detailed mailing list post that highlights some observed performance bottlenecks within the Linux kernel.

Sent out on Tuesday was the modules pull request for Linux 6.13 that have some low-level improvements but it noted that the biggest kernel modules highlight wasn't in that pull request itself but had been added by way of the memory management pull. This was a change by a Microsoft engineer around caching of kernel modules into huge pages.

Merged for the Linux 6.12 kernel was the long-awaited real-time "PREEMPT_RT" kernel support and allowing it to be enabled across x86/x86_64, ARM64, and RISC-V CPU architectures. With the Linux 6.13 kernel, LoongArch is joining the RT party.

Overnight the Rust for Linux lead developer Miguel Ojeda submitted the big set of Rust infrastructure/toolchain updates for the Linux 6.13 holiday kernel.

In between managing all of the pull requests being submitted during this two week long merge window for the Linux 6.13 kernel, Linus Torvalds has merged some of his own code this cycle.

Richard Hughes of Red Hat has released Fwupd 2.0.2 as the newest update to this open-source firmware updating solution for Linux systems.

Following all of the MM patches earlier this week sent in by Andrew Morton, on Sunday morning he sent out all of the non-MM patches that he manages for the Linux kernel. Notable for Linux 6.13 with this pull request is presenting the hung task counter as well as finishing off the folio conversion in the NILFS2 code.

One of the most prominent new features in Linux 6.12 was the merging of sched_ext for allowing extensible scheduler innovations by altering the scheduling behavior through (e)BPF programs. With the Linux 6.13 kernel there are some nice refinements to this extensible scheduler class.

The Direct Rendering Manager (DRM) subsystem updates have been submitted for the Linux 6.13 merge window in bringing many updates to the open-source kernel graphics/display drivers as well as the accelerator subsystem.

Andrew Morton on Monday submitted all the memory management "MM" related patches for the Linux 6.13 merge window. As usual there's a lot of interesting performance optimizations and other low-level refinements.

The crypto subsystem updates were merged yesterday for the in-development Linux 6.13 kernel. Among other crypto improvements are new optimizations for some algorithms when running on Intel and AMD x86_64 processors.

Merged last year for Linux 6.6 was multi-grain(ed) timestamps to address the current coarse-grained timestamps when updating creation time and modification time that a lot of I/O activity can happen in the once-per-jiffy timestamp. Just a few weeks in the Linux 6.6 kernel, multi-grain timestamps were removed due to bugs. The multigrain code went back to be reworked and now just over one year later the code has been re-merged into the mainline Linux kernel.

All of the scheduler feature changes were merged today for the Linux 6.13 kernel, including the introduction of the lazy preemption model.

The power management subsystem updates have been submitted for the newly opened Linux 6.13 merge window. As covered within individual articles over the past few weeks, the Linux 6.13 power management updates include some notable changes for both AMD and Intel systems.

The Linux kernel Workqueue (WQ) is used for handling asynchronous process execution. For the past many years there has been an upper limit on the number of workqueue execution contexts per CPU at 512, but with Linux 6.13 that is being quadrupled to a limit of 2048.

As expected, minutes ago Linus Torvalds just released the Linux 6.12 kernel as stable. Linux 6.12 brings many new features, new hardware support, and is rounded out by the fact of expected to become this year's Long Term Support (LTS) kernel version.

As part of the SLAB (SLUB) allocator updates pending for the upcoming Linux 6.13 cycle is a new "slab_strict_numa" option that is reported to further help ARM Linux performance such as for Ampere Computing servers.

Google software engineer Pasha Tatashin has proposed Page Detective as a new kernel debugging tool that is able to provide greater insight around the usage and mapping of physical memory pages.

Alongside the VFS pull requests on Friday for case insensitive Tmpfs support and atomic writes for EXT4 and XFS, Christian Brauner also submitted a pull request for introducing some new file abstractions for the Rust programming language within the Linux kernel.

While Linux 6.12 should be out this weekend with its many exciting features, following that will mark the start of the Linux 6.13 kernel cycle with what will be the first stable kernel release of 2025... Already there is a lot of exciting feature work expected to land during the Linux 6.13 merge window.

The Linux 6.12 kernel is expected to be released this coming Sunday, 17 November, barring any last minute issues that would force the stable kernel to be diverted to the following Sunday. Linux 6.12 is delivering many exciting new features and beyond that it's all the more exciting with it expected to be this year's Long-Term Support (LTS) kernel version.

Google engineer Saravana Kannan has posted a set of patches to better optimize async device suspend and resume handling within the Linux kernel. With these patches there are "significant improvements" to async device suspend/resume with testing being done on a Google Pixel 6 smartphone but other devices stand to benefit too.

Set to be merged during the upcoming Linux 6.13 merge window is support with the Rust programming language infrastructure for allowing in-place kernel modules.

Linus Torvalds just christened the Linux 6.12-rc7 kernel today for what will hopefully be the last release candidate before declaring Linux 6.12 stable next week Sunday.

Friday saw a final round of "drm-misc-next" feature updates ahead of the upcoming Linux 6.13 kernel merge window. The DRM Panic code continues to be enhanced for improving this "Blue Screen of Death" like experience on the Linux desktop.

A set of Friday night patches provide for some exciting context switching optimizations to the Linux kernel.

Yet another exciting feature expected to be merged for the upcoming Linux 6.13 cycle is the introduction of the Lazy Preemption model.

Linus Torvalds has just issued the Linux 6.12-rc6 kernel release as we close in on the stable Linux 6.12 kernel release later in November.

Linus Torvalds merged a patch on Wednesday that he authored that with reworking a few lines of code is able to score a 2.6% improvement within Intel's well-exercise "will it scale" per-thread-ops benchmark test case.

While the sched_ext extensible scheduler code was merged for Linux 6.12, work on sched_ext itself it is not over. New patches this weekend continue working on NUMA awareness for it with its default idle selection policy while similar work on CPU last level cache (LLC) awareness are slated for the upcoming Linux 6.13 cycle.

Following a busy week of kernel drama stemming from the Russian sanctions impacting Linux maintainers, Linus Torvalds is out with the Linux 6.12-rc5 weekly test candidate.

Sent out in original patch form this past week and already iterated to a second version this Sunday, a new proposal is underway to introduce "hung_task_detect_count" as a convenient means of tracking the number of times hung tasks are detected since boot.

Intel merged Linear Address Masking into the Linux kernel last year as a means of allowing user-space to store metadata within some bits of pointers without masking it out before use. LAM can be useful for virtual machines, sanitizers / profiling / memory tagging, and other uses. While the brand new Intel Arrow Lake and Lunar Lake CPUs support LAM, the Linux kernel is now disabling LAM out of security concerns.