Linus Torvalds announced on 4th November that Kernel 4.20-rc1 is tagged and pushed out, and the merge window is closed. Linux 4.20 brings a lot of prominent changes from AMD Vega 20 support getting squared away, AMD Picasso APU support, Intel 2.5G Ethernet support, the removal of Speck, peer-to-peer PCI memory support, and other new hardware support additions and software features.
Here are some of the features of 4.20-rc 1r:
- 70% of the patch is driver updates including changes in the gpu drivers
- Arch updates in x86, arm64, arm, powerpc, and the new C-SKY architecture),
- Updates in the header files, networking, core mm and kernel, and tooling
4. Tooling has been upgraded as well.
- The Kernel will have more than 350 thousand lines of new code!
- The AMD Vega 20 7nm workstation GPU support is now largely squared away for when this graphics card will be released in the months ahead.
- GPUVM performance improvements for the AMDGPU kernel driver.
- The Intel DRM driver now has full PPGTT support for Haswell/Ivy/Valley View hardware.
- Support for the Hygon Dhyana CPUs -the new Chinese data center processors based on AMD Zen.
- Scheduler improvements that should benefit asymmetric CPU systems like ARM big.LITTLE processors.
- Faster context switching on IBM POWER9.
- Several Btrfs performance improvements.
- Intel 2.5G Ethernet support was added via the new “IGC” driver.
- Xbox One S controller rumble support along with Logitech high-resolution scrolling and the new Apple Trackpad 2 driver are among the input hardware improvements.
- The Linux kernel is now VLA-free for variable length arrays to improve code portability and better performance and security.
- Speck crypto code was removed due to this crypto algorithm being quite controversial with its roots inside the NSA.
The highly anticipated WireGuard secure VPN tunnel is held off until the next cycle. The FreeSync / Adaptive-Sync / HDMI VRR bits are also being held off for DRM until the next cycle.
As the merge window closes, there will be some delay in the pull request which will be taken care of in the second week of the merge window.
The duration of the merge window is two weeks. Linus is considering making an explicit rule that he will stop taking new pull requests some time during the second week unless users have a good reason for why it was delayed.
He also hopes that by the time the next merge window rolls around, there will be a new automation for it, so that everybody just automatically gets notified when their pull request hit mainline.