Linux is a mostly free kernel similar to the Unix kernel. It is one of the main examples of free and open source software.
After two months of development, Linus Torvalds announced the release of Linux kernel 6.5. Notable changes include: support for the Intel TPMI power management mechanism, the cachestat system call, continuous integration of Rust language support, support for RISC-V vector instructions, and more.
In this new version of the Linux 6.5 Kernel, about 14674 fixes were made and 1294205 lines of code were added.
Main news in Linux 6.5
In this new version of the Linux 6.5 Kernel, the RAPL interface adds support for TPMI mechanism Used in Intel processors to enable power management features, this new interface complements the previously available RAPL MSR/MMIO interface and provides more flexible power limit settings.
Another change that stands out from the new version is that added cachestat() call, which has the function of consulting the cache status of the page for files and directories. A new system call allows userspace programs to determine which pages of a file are cached in main memory.
Unlike the previously available mincore() system call, the cachestat() call allows you to view more detailed statistics, such as the number of cached pages, dirty pages, evicted pages, recently evicted pages, and pages marked for rewrite.
For the part of the improvements that continue to be implemented in Rust support, It stands out that it has been possible to use the Rust 1.68.2 version, which stabilizes some of the functions used in the kernel. Improved pin start API as well as expanded capabilities of 'error', 'sync', 'str', 'task' and 'types' modules.
For ARM64 systems, support for PIE extension is implemented, which provides functionality to configure memory access rights. Instead of hardcoding permissions information into a memory page table, PIE uses the permissions array index specified in the registry.
In io_uring, the ability to store ring buffers and send queues in memory assigned in user space. The application can now independently allocate a region of memory and pass it to io_uring to take advantage of the ability to use large memory pages.
In addition to this, another of the novelties that stands out in this new version of Linux 6.5, the kernel work queues, which implement the detection and automatic marking of jobs with intensive CPU use.
In systems with processors Zen 2 and newer AMD, P-State driver is enabled by default instead of the CPUFreq driver for power management, plus the parameter X86_AMD_PSTATE_DEFAULT_MODE has been added to select the default P-State mode.
The file system Overlayfs, has been migrated to use the new mount API and changes have been made to organize the operation of the ComposeFS file system as a complement to the OverlayFS and EROFS file systems, rather than maintaining a separate implementation. In kernel 6.5, Composefs added support for "data-only" layers used for data only (separate from metadata).
New optimizations have been proposed for the Btrfs file system, since the data transfer implemented in synchronous mode for fast algorithms to calculate crc32c and xxhash checksums).
Of the other changes that stand out:
- AMDGPU driver added support for overclocking frequency of Radeon RX 7000 video cards.
- The i915 driver brings initial support for Intel Meteor Lake chips and adds the ability to use VRR on laptops with eDP displays.
- Significantly expanded support for USB4 controllers, including initial support for Intel Barlow Ridge controllers that support USB4 v2 (80 Gbps over USB Type-C).
- Support for MIDI 2.0 devices has been added to the ALSA audio subsystem.
- Added driver for NVIDIA SHIELD media consoles
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