Linux 5.5 features a host of changes and worthwhile improvements, and this post we spotlight the best of them!

Serving as the latest stable version of the Linux kernel, the Linux 5.5 release was announced on the Linux Kernel Mailing List (LKML) by Linus Torvalds, who said: “Despite the slight worry that the holidays might have affected the schedule, 5.5 ended up with the regular [release candidate] cadence and is out now.”

He goes on to describe the release as being “really tiny” — make of that what you will — and has named it “Kleptomaniac Octopus”.

Linux 5.5 is likely to be included in the upcoming Ubuntu 20.04 LTS release, which is due for release in mid April. This kernel version will also be back-ported to Ubuntu 18.04 LTS later in the year as part of the Ubuntu HWE stack.

If you want to install the mainline kernel on Ubuntu or another Linux distribution right now you can — but doing so is not recommended, comes with no support, and may break your system (but don’t worry: you get to keep both halves if it does).

Linux 5.5 Features

1. Raspberry Pi 4 Support

Raspberry Pi 4 Hero Image

Linux 5.5 comes with improved support for the Raspberry Pi 4 (more specifically the Broadcom BCM2711 chip used in it). This means that the latest and greatest version of the famous single-board computer (SBC) now works “out of the box” on mainline Linux — nice!

The Raspberry Pi isn’t the only SBC to pick up support in this release. Linux Kernel 5.5 also features better compatibility with the NanoPi Duo2, 4, RK3308, and Ugoos AM6 boards.

2. SSD Temperature Info

Anyone rocking an NVMe SSD on their Linux machine will appreciate a new mainline driver for reporting SSD temperature via HWMON in sysfs, negating the need for any bespoke root-level user-space utilities.

3. Logitech G15 Gaming Keyboard

Linux 5.5 includes a driver for two of Logitech’s older gaming keyboards, namely the first version Logitech G15 and the second version Logitech G15, thanks to code committed by Red Hat’s Hans de Goede.

Whilst neither of these keyboards are new — the G15 v1 was released in 2005 — they remain popular among gamers due to an array of premium-level features, macro buttons, backlight modes, and a nifty built-in LCD screen.

4. Several ext4 Tweaks

As arguably the most widely used file system in Linux systems, Linux 5.5 ships with some new features for the ext4 filesystem — though few will result in any user-visible changes.

The ext4 filesystem picks up support for encryption on file systems where the block size is less than the page size; reworks journal credit handling to avoid instances where the journal might run out of space; and gains direct I/O via iomap.

5. Faster btrfs Copying

Keeping with file systems for a moment, this kernel release gains support for three and four copy modes in RAID1 on btrfs file systems. Up from two copy modes previously, this change allows data to be replicated across more drives simultaneously.

6. ExFat Finesse

As far as I can make out — do correct me in the comments if I’m writing — the much hyped Linux kernel driver for Microsoft’s exFAT filesystem continues to be improved …albeit in the staging branch.

There’s nothing major to report on that front here, with just minor code clean ups, fixes, and polishing — however an entirely newer (and potentially better) exFAT driver is being prepped for possible inclusion in Linux 5.6.

7. Chromebook Privacy Mode

Among various Chromebook-specific merges included in the latest kernel is support for an electronic privacy screen mode in an as-yet unreleased Chromebook model.

The electronic privacy filter allows users to press a button on the keyboard to instantly “mask” their display to anyone looking over their shoulder. It works using a combination of backlight and a special film coating on the physical display.

Other notable additions for Chromebook owners include ‘wake on voice’ support for select devices that support it; support for Dell’s USB PowerShare Policy control; and keyboard backlight LED support on a crop of upcoming models.

8. System76 ACPI Driver

System76 Linux laptop owners benefit from the inclusion of the System76 ACPI driver in main, saving folks using Coreboot on their devices from needing to download or install it separately.

What does the System76 ACPI driver actually do? Well, it adds support for function (Fn) key combinations, the keyboard backlight, and airplane mode LEDs.

9. Graphics

As you’d expect of any new kernel releases there is a glut of GPU related goodies on offer, including more effort to get AMD Arcuturus Vega-based graphics cards up and running, as well as Intel ‘Tiger Lake’ GPUs.

ARM fans will appreciate the improved Allwinner Cedrus driver, which now includes HEVC/H.265 video decoding (courtesy of a 2018 crowdfunding campaign).

Another niche highlight in this update is support for AMD OverDrive clocking on Navi GPUs. If you happen to have a Radeon RX 5000 graphics card, and you don’t mind potentially breaking it, get overclocking from the command line!

10. Thunderbolt 3

I can’t imagine there are too many modern MacBook owners running Linux (what with the can-it/can’t-it debate over the Apple’s t2 technology chip) but those who do may be interested to know that Linux 5.5 includes initial Thunderbolt 3 support.

Thunderbolt 3 is a USB Type-C port that can handle data transfer, video output and charging via a single connector. It’s not exclusive to Apple devices but, in this kernel release, only Thunderbolt 3 on Apple devices gains software connection manager support.

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