Linux 6.1 Features Include Initial Rust Code, MGLRU, New AMD CPU Features, More Security

Now that Linux 6.1-rc1 was released, here is my look at all of the interesting kernel changes and new features that landed over the past two weeks. Linux 6.1 is shaping up to be another exciting kernel with many new software features, new hardware enablement work, and other changes for this end-of-year 2022 kernel version that is also likely to be the next Linux LTS release.

Among the key highlights for Linux 6.1 are the initial Rust infrastructure has been merged, MGLRU, various new AMD CPU features from adding the Platform Management Framework (PMF) to new perf features, faster file sharing between Linux hosts and guest VMs using 9P, the Kernel Memory Sanitizer (KMSAN) was merged, warning by default over W+X mappings, preparations for WiFi 7 and 802.11be on the networking side, new open-source GPU driver work, and much more.

Beyond all the exciting feature changes, Linux 6.1 is also notable in likely being the Linux 2022 LTS kernel release to be supported for the long-term.

Processors:

- The IBM POWER/PowerPC code has KFENCE for 64-bit, system call wrappers, and execute-only memory support.

- The LoongArch CPU port brings TLB/cache code rework, QSpinLock support, EFI boot, support for perf events, Kexec handling, eBPF JIT support, and various other features for this Chinese CPU architecture.

- Linux 6.1 is dropping BF16 support for Cortex-A510 processors due to a hardware issue that otherwise cannot be worked around on Linux.

- AMD IOMMU v2 page table work as part of the AMD vIOMMU hardware-assisted IOMMU virtualization for EPYC 7002 "Rome" processors and newer.

- AMD CPU cache-to-cache and memory reporting with perf and newer AMD processors and LbrExtV2 support for Zen 4 CPUs.

- The AMD Platform Management Framework (PMF) was merged for better thermal/power/noise handling with next-generation AMD Ryzen devices.

- Support for new Arm SoCs and various new Arm devices.

- Faster Intel memory error decoding.

- AMD P-State fixes and s2idle fixes for AMD Rembrandt laptops.

- Arm support for disabling Spectre-BHB mitigation at run-time due to the heavy performance cost.

Graphics / GPUs:

- Continued Intel Meteor Lake enablement.

- Improved Intel GPU firmware handling.

- Various Intel Arc Graphics DG2/Alchemist improvements.

- AMDGPU gang submit support that is needed by the RADV Vulkan driver for proper mesh shader support.

- Mode2 reset support for RX 6000 series RDNA2 GPUs.

- Continued enablement work around AMD RDNA3 GPUs.

Linux Storage / File-Systems:

- RISC-V's default kernel configuration enables various CD-ROM image formats. Not that you are likely to rock a physical CD drive with your RISC-V system, but for install images and other media in ISO9600 / Joliet / ZISOFS file-system formats.

- FSCache-based shared domain support for EROFS with container use-cases being the initial target.

- EXT4 fixes and performance optimizations.

- Significant Btrfs performance optimizations and other work to this increasingly used Linux file-system.

- Support for statx() to report direct I/O alignment details.