Some days ago Linus Torvalds announced the general availability of the stable version of Linux 5.18, a version that arrives precisely two months after the Linux 5.17 kernel series and received eight RC (Release Candidate) stages throughout its development cycle, which helped kernel developers fix bugs and improve existing features.
Among the most relevant changes of this new version of Linux Kernel 5.18 include the change to the C11 compilation standard, support for "user events" in the tracking system, support for the "host system management port" function » from AMD, support for 64-bit integrity checksums on NVMe devices, and more.
Main news in Linux 5.18
Many additions from Intel have been made in this new version of Linux Kernel 5.18, including the new driver “Hardware Feedback Interface” (HFI) for hybrid processors such as Alder Lake, "Software Defined Silicon" (SDSi) has been merged to enable silicon features licensed with future Intel CPUs, "Intel Indirect Branch Tracking" (IBT) as part of "Control-Flow Enforcement Technology”, “ENQCMD” is re-enabled for Sapphire Rapids and more. Intel PECI, the Platform Environmental Control Interface, was also merged for the interface between CPU and BMC on Intel server platforms.
The preparations for Intel IPI virtualization also landed in Linux 5.18, while the actual activation should be there for the v5.19 cycle. As for the new Intel in the graphics space, Linux 5.18 offers support for the DG2 G12 sub-platform, support for Intel Alder Lake N graphics and various DG2/Alchemist enable bits.
There's also work on AMD EDAC for Zen 4 CPUs, nested virtualization improvements from AMD and other work on Zen 4. KVM with Linux 5.18 is also compatible with AMD virtual machines up to 511 vCPUs, up from 255 vCPUs today, and outperforms the latest generation EPYC. servers that offer higher number of cores with Bergamo. As for AMD graphics, Linux 5.18 enables the AMDGPU's FreeSync "video mode" by default, which was hidden behind a module option in previous kernels.
The first blocks of IP are also enabled for GPUs and APUs next generation, but more are planned in kernel 5.19. Regarding the hardware, the "Raspberry Pi Zero 2W" has full Linux kernel support in this version.
In addition, the ReiserFS file system has been deprecated and is expected to be removed in 2025. The deprecation of ReiserFS will reduce the effort required to maintain common file system changes to support the new mount, iomap, and volume APIs. .
It is also highlighted that the code for calculating statistics has been redesigned in Device-mapper drivers, which has significantly improved accounting accuracy in drivers like dm-crypt. For NVMe devices, support for 64-bit checksums for integrity checks has been implemented.
Moreover, it is highlighted that the integration of a set of patches has begun, which can significantly reduce kernel rebuild time by restructuring the hierarchy of header files and reducing the number of cross dependencies. Kernel 5.18 includes patches that optimize the structure of the scheduler header files (kernel/sched).
The kernel code can use the C11 standard, published in 2011. Previously, code added to the kernel had to comply with the ANSI C (C89) specification, which was formed in 1989. Changed the '–std=gnu89' option to '–std=gnu11 -Wno-shift- negative-value' in the 5.18 kernel build scripts. The possibility of using the C17 standard was considered, but in this case it would be necessary to increase the minimum supported version of GCC, while the inclusion of C11 support conforms to the current requirements for the GCC version (5.1).
As well Extended tools for tracking applications in user space are highlighted. The new kernel version adds the ability for user processes to create user events and write data to the trace buffer, which can be viewed through common kernel trace utilities such as ftrace and perf.
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