Linux long term support kernels extended from two years to six years
Long term support (LTS) kernels for Linux will be extended from two years to six years, meaning potentially greater security and bug fixes across Android devices and more.
The announcement was made by Ilian Malchev, Google senior staff engineer, keynoting the annual Linaro Connect jamboree, held this year in San Francisco.
Aside from the intriguing interplay of a Google executive discussing Linux at a Linaro event, the announcement is an interesting one in the context of Android development. Current Linux LTS kernels, of two years, simply don’t cut it for Android and ARM devices when they previously did for PCs – and the move to six years marks the high point of a series of initiatives Google undertook with Android O.
Indeed, Malchev admitted that until O Google had not kept statistics on the kernels that Android devices ran. His annotations of kernels – 3.4 for Lollipop, 3.1 for Kit Kat, 3.18 for Nougat – in the presentation were based on memory.
“Greg Kroah-Hartman [current Linux kernel maintainer] has given me permission to announce this here – he will extend LTS to six years starting with kernel 4.4, and a lot of this is underpinned by our joint work with Linaro,” said Malchev. “A six-year LTS kernel is really an amazing feat that we have to pull off if we hope for any of our devices to get all the security fixes, all the bug fixes from upstream that are available.”
Malchev illustrated the issue with two slides in particular (below). Current stable long-term support only takes care of the initial device release and little else. “With today’s situation, what Google wants to see with our partners is once a device is launched, it gets upgraded four times to a new Android version,” he said. “That’s basically the lifespan of a phone – but you get lucky if you get one of these.”
This comes under the wider umbrella of Project Treble, first announced in May and focusing on giving Android a modular base and changing the low-level system architecture.
Malchev explained Treble to attendees – as indeed in the blog post originally announcing it – through a ‘grossly over-simplified’ look at the lifespan of an Android device. Google initially releases an AOSP (Android Open Source Project) – “a bunch of projects that are largely divorced from any actual end-consumer hardware” – before OEMs or ODMs add customisations missing from the project, and then adding the adaptation layer for the SoC before qualifying to the actual device.
Except it doesn’t quite work like that. “This ugliness,” said Malchev, referring to a slide, “is why it’s difficult to upgrade Android to new versions of itself, and also to launch.”
Malchev added that Project Treble’s goals, of making architectural changes to the Android platform, as well as operational changes and compatibility requirements, had to be done in the one operating system cycle. “It takes time for new Android releases to trickle down to the rest of the ecosystem,” he said.
Kroah-Hartman confirmed the news on Twitter shortly after the announcement was made, with 4.4 being updated on Kernel.org to February 2022 as an end of life date.