Linux Kernel 4.19 – Long Term Support, USB Type C, and WiFi 6


This was a rather special release due to the fact that, at about half way through the process, Linus Torvalds left the helm of Linux kernel development to take a rare break. However, Greg Kroah-Hartman took over until the release was ready and is now handing the reins back to Torvalds.

Another interesting fact about this iteration is that 4.19 will be a Long Term Support (LTS) kernel. That is, it will receive updates and patches to keep it safe and maintained for at least a couple of years. The last LTS kernel (which is still supported) was 4.14, released in November 2017.

On the purely technical side, among many other things, 4.19 is getting a new USB Type C display mode driver. This means exactly what it says on the box: soon you will be able to use the USB Type C on your machine to stream video to a display.

Also, the kernel at last gets a built-in GPS subsystem. Obviously, Linux has supported GPS devices for years, but this support was pretty non-standard and dependent on external and ad hoc modules that varied from device to device. The GNSS (Global Navigation Satellite System) subsystem puts an end to that. According to the Phoronix article on the matter, GNSS abstracts the underlying hardware interfaces and will have a front end in user space that will allow programs to read the data in standardized way and format. And, once more, developers have had to deal with the Spectre bug. This time, it was to add mitigations for affected IBM POWER CPUs.

Other things to look forward to in Linux kernel 4.19:

  • A new queuing discipline for the network packet scheduler. Dubbed CAKE (for Common Applications Kept Enhanced), it aims to speed up home network routers and links. By shaping data transmissions over the network, it helps reduce the problem of buffering and latency that will slow down your downloads, make your video-stream stutter or get you kicked off CS:GO.
  • A brand new (and, for now, experimental) read only file system called EROFS (for Enhanced Read-Only File System). It is designed to be lightweight and modern in its design and is created by Huawei for situations where a high-performance read-only file system is needed. This is useful in firmwares for mobile devices or for Live CDs.
  • Preliminary support for the upcoming WiFi 6 (aka 802.11 ax) protocol. WiFi 6 widens the band for network transmissions and will be substantially faster than current WiFi networks, as a wider band means less congestion. Less congestion will also mean data can be transmitted more reliably. That said, there are still only a few 802.11ax-enabled devices out there, but when they come, Linux will be ready!

As usual, there’s much more to learn about kernel 4.19 on the Linux Kernel Mailing List. You can also visit the articles on Phoronix or check out the Kernel Newbies report

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