Linux is a mostly free kernel similar to the Unix kernel. It is one of the main examples of free and open source software.
Linus Torvalds presented the release of the Linux Kernel 6.8, which arrives after two months of development and among the most notable changes of this release is the addition of the Xe driver for Intel GPUs, the new protection mode for block devices, the implementation of the Deadline server task scheduling mechanism , automatic optimization of merging identical memory pages, among other things.
The Linux 6.8 kernel presents a series of significant improvements that cover various aspects, from performance and security to compatibility with hardware and architectures. The release includes 15,641 developer fixes, with a patch size of 44 MB. The changes are largely focused on device drivers and code updates for hardware architectures.
Main news in Linux 6.8
Among the most notable improvements of this new version of the Linux Kernel 6.8 is the disk subsystem, I/O and file systems, where changes have been made to block direct writing to mounted block devices (by default, the mode is disabled and requires the BLK_DEV_WRITE_MOUNTED parameter to be specified when compiling), as well as new system calls for detailed information on mounted file systems.
In XFS, work has continued on the ability to use the f utilitysck to check and fix problems identified online, without unmounting the file system, while in Ext4 now uses dioread_nolock call for smaller blocks than one page of memory, which improves performance by eliminating unnecessary locks.
Regarding memory and system services, one of the most notable features of this new version is the Zswap subsystem improvement, since you can now force the unloading of rarely used memory pages, thus freeing up RAM when necessary. Additionally, a new mode has been introduced that disables writing back to the swap partition if the write fails, preventing the download of pages that are already in the Zswap pool.
Another important addition is the SCHED_DEADLINE server, designed to address CPU underutilization by regular tasks when the CPU is monopolized by high priority tasks, the DAMON (Data Access MONitor) subsystem has been enhanced to allow monitoring of access to data in RAM and automatically adjust memory consumption according to specific quotas. The introduction of support for large memory pages and optimization of the BPF program checker are other significant improvements in kernel 6.8.
In the field of virtualization and security, AppArmor has migrated to using the SHA-256 algorithm for rule verification, the removal of the strlcpy() function from the kernel represents a step forward in terms of security, since this function, although designed to prevent buffer overflows, has proven to be prone to certain vulnerabilities.
In the field of virtualization, the hypervisor KVM has introduced support for the guest_memfd subsystem, which provides specific memory management capabilities for guest systems, support for LAM mode has been enabled on Intel processors, allowing part of the 64-bit pointer bits to be used to store metadata, the iaa driver has been added (IAA Compression Accelerator), which uses the Intel Analytics Accelerator (IAA) cryptographic accelerators to accelerate data compression and decompression using the DEFLATE method.
SELinux has introduced the "init" SID to identify startup processes that run before SELinux policies are applied, improving security policy management on the system.
The network subsystem has seen improvements in efficiency caching as well as TCP speed thanks to a reorganization of the underlying data structures. Additionally, the bpfilter subsystem has been removed and low-level optimizations have been made to improve performance.
On the equipment side, new drivers have been added for Intel, AMD, NVIDIA and other brands of GPUs, as well as support for a variety of ARM64 SoCs and ARM devices. However, it is important to note that support for ARM11 ARMv6K SMP processors has been discontinued.
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