As expected, today, December 11, 2016, Linus Torvalds unleashed the final release of the highly anticipated Linux 4.9 kernel, a major update that introduces numerous exciting new features, updated drivers, and other under-the-hood improvements.

Linux kernel 4.9 entered development in mid-October, on the 15th, when Linus Torvalds decided to cut the merge window short by a day just to keep people on their toes, but also to prevent them from sending last-minute pull requests that might cause issues like it happened with the release of Linux kernel 4.8, which landed just two weeks before the first RC of Linux 4.9 hit the streets.

But the wait is now over, and Linux kernel 4.9 is now here as the mainline kernel, the most advanced version available on the market for GNU/Linux distributions, and it's coming soon to a distro near you, such as the rolling Arch Linux, Solus, or even OpenSuSE Tumbleweed, but also to Fedora, immediately after it hits the stable channel, which should happen when the first point release arrives, namely Linux kernel 4.9.1.

"I'm pretty sure this is the biggest release we've ever had, at least in number of commits. If you look at the number of lines changed, we've had bigger releases in the past, but they have tended to be due to specific issues (v4.2 got a lot of lines from the AMD GPU register definition files, for example, and we've had big re-organizations that caused a lot of lines in the past: v3.2 was big due to staging, v3.7 had the automated uapi header file disintegration, etc). In contrast, 4.9 is just big," said Linus Torvalds in today's announcement.

The many features of Linux kernel 4.9

As mentioned before, there are many great new features implemented in Linux kernel 4.9, but by far the most exciting one is the experimental support for older AMD Radeon graphics cards from the Southern Islands (SI) / GCN 1.0 family, which was injected to the open-source AMDGPU graphics driver. This means that it needs to be enabled at compile time, and you'll need X.Org Server 1.19.0 and xf86-video-amdgpu 1.2.0 too.

There are also various interesting improvements for modern AMD Radeon GPUs, such as virtual display support and better reset support, both of which are implemented in the AMDGPU driver. For Intel GPU users, there's DMA-BUF implicit fencing, and some Intel Atom processors got a P-State performance boost. Intel Skylake improvements are also present in Linux kernel 4.9.

Of course, there are also the usual fixes and enhancements for various filesystems and hardware architectures, including Btrfs, XFS, and F2FS, UBIFS support for OverlayFS, FUSE support for POSIX ACLs, OverlayFS SELinux support, better Non-Volatile Dual In-line Memory Module (NVDIMM) support, MD RAID improvements, support for many ARM platforms, including Raspberry Pi Zero, as well as KVM and Xen changes.

Memory protection keys support, virtually mapped kernel stacks, Greybus driver subsystem that provides device discovery and description, as well as network routing and housekeeping, and Intel Integrated Sensor Hub Support (ISH) are also things you should get excited about in Linux kernel 4.9, whose source archive you can download right now from kernel.org or through our web portal. And yes, the merge window for Linux kernel 4.10 is now open!