May 16, 2016

Linus Torvalds Ships "Fairly Big" Linux Kernel 4.6 Release

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Linux kernel 4.6 “Charred Weasel” has a number of interesting changes.
Linus Torvalds christened the Linux kernel 4.6 release "Charred Weasel" in a homage to the poor animal that recently perished after it gnawed through an electrical cord and shut down the particle accelerator at the Large Hadron Collider.

Linus Torvalds this week released the final code for version 4.6 of the Linux kernel. This release comes two months after the previous 4.5 version and has gone through seven release candidates.

“The 4.6 kernel on the whole was a fairly big release - more commits than we've had in a while,” Torvalds wrote in his release notes on the LKML mailing list. “But it all felt fairly calm despite that.”

Despite the relative calm of the last few release candidates, Linux kernel 4.6 “Charred Weasel” does come with its fair share of interesting changes. Many end users will notice performance improvements in the temperature control of their laptops, for example, because this version closes a quite serious bug that caused thermal throttling in some models of Lenovo laptops. Support for Dell laptops, including their Alienware gaming line of machines has also been improved.

Embedded machines also get a boost with the support of 13 new ARM-based SoCs. These include SoCs from Allwinner, LG, Qualcomm, and Broadcom, among other manufacturers. Devices that will see an improvement of support for their boards include several WiFi routers, the Nexus 7 smartphone, and the Raspberry Pi nano-computer.

Continuing on the topic of Linux for ARM, support for the 64-bit ARM architecture is chugging along nicely. Both performance enhancements and new features have made their way into the current kernel, which also now supports, among other things, the half-precision floating point format for binary numbers.

Another architecture on the way to being supported by the kernel is the line of new Power9 processors. This hardware is typically built into high-end servers and, although Power8 and earlier versions are fully supported by the kernel, Power9 remains very much work in progress. However, IBM has designated Linux as the default operating system for their line of Power-based computers (even over their AIX), which means that, with IBM's input, it is likely that the Power9 will be supported shortly.

Most of the big changes for this version happened early on in the development cycle, with things quieting down after that, prompting Torvalds to remark that the only big change in the latest release candidates was the correction of a long-standing InfiniBand interface problem. Infiniband is used in high-performance computing, so, unless you are administering a supercomputer, it is unlikely the change will affect you.

Despite the above, however, the last week of this development cycle was quite hectic according to Torvalds, with a slew of patches pouring in, most of which were corrections for drivers, including Radeon, AMD GPU, and network drivers.

From release candidate 6 onwards, Torvalds christened this release "Charred Weasel" in a homage to the poor little furry fellow that recently got fried by accident in the particle accelerator at the Large Hadron Collider. The critter gnawed through a power line, causing a short in the collider and shutting down the installation for weeks in the process. As the LHC runs its own variant of Linux on the cluster that analyzes the data from experiments, it is an apt tribute.

Other changes to the kernel include:

  • Kernel 4.6 now supports OrangeFS, a modern scale-out network file system designed for use on high-end computing systems. OrangeFS provides very high performance access to multi-server based disk storage.

  • Support for the Synaptics RMI4 protocol has also been added in this version. This translates into an improved support for touchscreens on a wide range of mobile devices.

  • Developers have improved the drivers for many HIDs (read "game controllers") as well as for Intel's Skylake line of processors.

  • Version 4.6 also improves the security of the EFI firmware, isolating its context from the rest of the kernel.

  • Other security updates, including kernel memory protection by default on ARMv7+, arm64 and mandatory on x86, and more oulined by Kees Cook, are part of an ongoing effort to create "airbags for the kernel" by preventing bugs from becoming security issues. 

For more information, read the official announcement of the release or visit Phoronix, where they have more on the most significant changes that made their way into 4.6.

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