The Most Notable New Features Of The Linux 4.20 Kernel
Written by Michael Larabel in Linux Kernel on 20 December 2018 at 06:51 PM EST. 5 Comments
LINUX KERNEL --
As it's been two months since the Linux 4.20 cycle got underway with the feature-packed merge window and with this kernel expected out just in time for Christmas, here is a look back at some of the biggest and most notable features to this imminent kernel release.

For those vastly behind on their Phoronix reading or just let slip all the new features of Linux 4.20, here is what I would say makes me most excited for the 4.20 kernel.

- New hardware support! As is usually the case, Linux 4.20 brings a lot of new hardware support. New hardware support includes bringing up the graphics for AMD Picasso and Raven 2 APUs, continued work on bringing up Vega 20, Intel has continued putting together its Icelake Gen 11 graphics support, there is support for the Hygon Dhyana CPUs out of China based upon AMD Zen, C-SKY 32-bit CPU support, Qualcomm Snapdragon 835 SoC enablement, Intel 2.5G Ethernet controller support for "Foxville", Creative Sound Blaster ZxR and AE-5 sound card support, and a lot of smaller additions.

- Besides new hardware support when it comes to graphics processors, in the DRM driver space there is also VCN JPEG acceleration for Raven Ridge, GPUVM performance work resulting in some nice Vulkan gaming boosts, Intel DRM now has full PPGTT support for Haswell/IvyBridge/ValleyView, and HDMI 2.0 support for the NVIDIA/Nouveau driver.

- On the CPU front there are some early signs of AMD Zen 2 bring-up, nested virtualization now enabled by default for AMD/Intel CPUs, faster context switching for IBM POWER9, and various x86_64 optimizations. Fortunately the STIBP work for cross-hyperthread Spectre V2 mitigation was smoothed out over the release candidates that the performance there is all good now.

- Btrfs performance improvements, new F2FS features, faster FUSE performance, and MDRAID improvements for RAID10 round out the file-system/storage work.

- One of the technical highlights of Linux 4.20 that will be built up moving forward is the PCIe peer-to-peer memory support for device-to-device memory copies over PCIe for use-cases like data going directly from NICs to SSD storage or between multiple GPUs.

- The Linux kernel is now VLA-free for better code portability, possible performance benefits, and greater security with laying to rest variable length arrays. Also on the low-level kernel side, the XArrays data structure was introduced.

More Linux 4.20 changes are outlined in our feature overview. The Linux 4.20.0 kernel is expected to be out on Sunday followed by the opening of the Linux 4.21 kernel merge window for what is sure to be another exciting cycle.
About The Author
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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