After two months of developmentLinus Torvalds introduced the release of the new version of the Linux kernel 5.1, version that adds fixes and compatibility to new hardware components.
Between the most notable changes of this new version of the Kernel includes the new io_uring interface for I / O asynchronous, the ability to use NVDIMMs as RAM as well as support for shared virtual memory in Nouveau.
Main novelties of the Linux Kernel 5.1
As we mentioned in this new version a new interface has been implemented for asynchronous I / O io_uring, which It is characterized by supporting I / O polling and the ability to work with both the buffer and without the buffer.
As part of the io_uring API, the developers tried to remove the flaws of the old aio interface.
In terms of performance, io_uring is very close to SPDK and significantly ahead of Libaio when working with polling enabled.
For the file system Btrfs added the ability to adjust the compression level for the zstd algorithm, which can be considered as the best compromise between the fast but inefficient lz4 and the slow but well compressed xz.
Among other improvements in Btrfs, we can see the addition of lazy scan of a subtree to reduce the load and the implementation of a new ioctl to control the disconnection of the device;
Another novelty is that it was added to the Linux Kernel 5.1 the ability to boot from the file system located on the device mapper device without using initramfs.
Starting with the current version of the kernel, device mapping devices can be used directly during the boot process, for example, as a partition with a root file system.
EXT2 adds support for statx system call with the implementation of a more efficient and functional version of stat (), which returns extended information about the file, including the file creation time and filesystem-specific flags;
Virtualization and security
The option prctl () PR_SPEC_DISABLE_NOEXEC has been added to control speculative execution of the instructions for the selected process.
The new option will allows you to selectively control protection against speculative execution for processes that can potentially be attacked using a Specter attack
The LSM SafeSetID module was implemented, which allows system services to safely manage users without increasing privileges (CAP_SETUID) and without obtaining root privileges.
Memory and system services.
The kernel of Linux 5.1 adds secure implementation of token delivery, taking into account the possibility of PID reuse.
Added ability to use persistent memory devices (persistent memory, for example NVDIMM) as RAM.
Until now, in the kernel, such devices were supported as storage devices, but now they can also be used as additional RAM.
Hardware
Another of the main changes in this new version is the adding memory management support to the Nouveau driver, allowing the CPU and GPU to access shared synchronized memory areas.
Shared virtual memory (SVM) is implemented on the basis of the memory management subsystem, which allows you to use devices with their own memory management units (MMUs) that can access main memory.
Including with the help of HMM, It can organize a joint address space between the GPU and the CPU, in which the GPU can access the main memory of the process.
Intel DRM-driver for Skylake GPU and newer (gen9+) includes default quick start mode, which removes unnecessary mode changes during startup. New device identifiers based on Coffelake and Ice Lake microarchitectures have been added.
GVT (GPU Virtualization) support has been added for Coffelake chips. For virtual GPUs, VFIO EDID support has been implemented.
Finally, the support for GPU Vega10 / 20 BACO to the amdgpu driver is also highlighted. Vega 10/20 power management tools and Vega 10 cooler management tables implemented.
This new version of the Kernel has many more changes and support for other devices. If you want to know more about it, you can consult the following link.