Linux kernel adds over a million lines of code to support latest chips

Release candidate for Linux kernel version 4.2 extends AMD GPU support among other updates

The Linux kernel is getting a bumper update with the release candidate of version 4.2, which adds over a million new lines of code, the majority of which is accounted for by drivers to support AMD's GPU architecture and extended ARM support.

Pushed out over the weekend, the Linux kernel 4.2-rc1 release is described by Linux creator Linus Torvalds as one of the biggest ever updates, and closely follows the official release of the 4.1 kernel in June.

Torvalds wrote in a message on the Linux Kernel Mailing List forum that the bulk of the new code in this release can be attributed to new AMD GPU register description headers to support new capabilities in AMD's latest chips.

"The reason for that huge number of lines is largely a single source: the bulk of this by far is from the new AMD GPU register description headers. In fact, just those register descriptor headers alone are about 41 percent of the entire patch," he said.

"The rest of the new AMD GPU driver is another eight percent of the total, so we're in the somewhat odd situation where a single driver is about half of the whole rc1 in number of lines."

However, despite this impressive number, the latest release candidate actually contains fewer commits than earlier releases such as 3.15-rc1, and also removes about a quarter of a million lines in other changes.

Aside from the new AMD GPU support, the rest of the changes address updates for other processor architectures, such as ARM chips, but also some low-level x86 changes, comprising source code reorganisation for x86 entry code and floating point handling clean-ups.

"That's fairly unusual, with low-level x86 code being fairly stable and seldom seeing those kinds of big changes," Torvalds said.

These changes will not immediately affect most end users, as the kernel code will need to be incorporated into distributions maintained by Linux vendors such as Red Hat and Canonical, which is how the majority of Linux users receive such updates.