Linus Torvalds has said that version 5.8 of the Linux kernel is “one of our biggest releases of all time”.
All going well, the stable release should appear sometime in August.
Introducing the release candidate, Torvalds said it was “right up there with v4.9, which has long been our biggest release by quite a bit in number of commits.” That said, the 4.9 kernel was “artificially big” because of a couple of special factors, whereas 5.8 is a “more comprehensive release.”
Torvalds said: “The development is really all over the place: there’s tons of fairly fundamental core work and cleanups, but there is also lots of filesystem work and obviously all the usual driver updates too. Plus documentation and architecture work.” He added: “We have modified about 20 per cent of all the files in the kernel source repository. That’s really a fairly big percentage, and while some of it _is_ scripted, on the whole it’s really just the same pattern: 5.8 has simply seen a lot of development.”
While the code for the kernel is large, only a small part of it ends up in any individual system, since the kernel source contains code for every chip architecture and hardware it supports. In early 2018, maintainer Greg Kroah-Hartman said that “an average laptop uses around 2 million lines of kernel from 5,000 files to function properly.” At the time, there were 25 million lines of code in the kernel, whereas now there are over 28 million.
What’s in the upcoming release? Michael Larabel of Phoronix has done a summary of changes here. Highlights include new and updated drivers, initial boot support for the forthcoming IBM/OpenPOWER POWER10 processors, KVM (Kernel-based virtual machine) improvements including support for nested AMD live migration, updates to the Samsung-backed file system driver for Microsoft’s exFAT, and accelerator support for the Habana Labs Gaudi AI Training Processor – this last one mentioned by Torvalds as accounting for a large chunk of new code. There is also support for Thunderbolt in Intel’s Tiger Lake processors.
Torvalds claimed that “5.8 is up there with the best, despite not really having any single thing that stands out.”
Does lots of changes mean trouble ahead? “Famous last words. Let’s see what happens during the rest of this release. But at least right now, while 5.8 looks like a very large release, I don’t get the feeling that it’s particularly troublesome,” he said. “Knock wood.”