Linux 4.19 has arrived with new CAKE router tech, WiFi 6 support, and a lightweight EROFS file system. Meanwhile, Linus Torvalds returned to duty from his self-imposed time-out to publicly discuss the new Code of Conduct.



In conjunction with this week’s Open Source Summit and Embedded Linux Conference events in Edinburgh, Scotland, the Linux kernel project released Linux 4.19. This was the first kernel that was not signed off by Linux creator Linus Torvalds, who had stepped away from his Linux herding duties for six weeks to try to improve his online behavior. Long-time number two kernel honcho Greg Kroah-Hartman (GKH), who officially released the kernel, will continue to share rights to the kernel tree, Torvalds told ZDNet in an interview that discussed the new Code of Conduct (CoC), BPF VMs, and more (see farther below).



Linux 4.19 highlights

Linux Kernel 4.19 is more than the usual hodgepodge of tweaks, improvements, and security enhancements. In addition to formally launch of the new CoC, it introduces several significant new technologies.

According to the LinuxNewbies overview, Linux 4.19’s new CAKE network queue management technology simplifies router setup and “fights bufferbloat” by “squeezing the most bandwidth and latency out of even the slowest ISP links and routers. CAKE is particularly aimed at home routers.

The 4.19 release provides new minimum guarantees for I/O latency targets and a new asynchronous I/O polling interface. Other features include improved security patches for Intel CPU vulnerabilities. There’s also early support for the faster, more power efficient 802.11ax, which is called Wi-Fi 6 under the new WiFi naming scheme.

The 4.19 release introduces an experimental EROFS (Enhanced Read-Only File System) file system. EROFS is designed for constrained devices that require high-performance read-only access. The lightweight file system provides “VLE compression support, focusing on random read improvements, keeping relatively lower compression ratios, which is useful for high-performance devices with limited memory and ROM space,” says LinuxNewbies.



Rock960

Linux 4.19 also boosts support for Arm and MIPS chips. In the Arm realm, there’s improved support for Allwinner, Amlogic, MediaTek, Rockchip, Qualcomm, and Samsung SoCs. There’s specific support for the Allwinner based Pine64 Pinebook laptop and Vamrs’ 96Boards compatible, RK3399 based Rock960 SBC (AKA “Ficus”), among other targets.



BPF: Linux friend or foe?

The ZDNet interview with Torvalds covered an emerging, and somewhat controversial technology called BPF (Berkeley Packet Filter) virtualization that is affecting Linux from outside the kernel. According to the BPF site, the technology “allows users to run a small piece of code quickly and safely” within the kernel to support dynamic tracing. The in-kernel VM, which was the topic of a keynote in Edinburgh, is already being incorporated into various security technologies.

BPF breaks the unwritten Linux rule that the kernel should be fully separated from user-space processes. For the record, Torvalds supports BPF because it “allows people to do specialized code” for tracing, statistics, and network filtering “that isn’t enabled until asked for.”

Linus returns

Linus Torvalds, who spoke to ZDnet’s Steven J. Vaughan-Nichols after meeting with top Linux maintainers in Edinburgh at a Maintainer’s Summit event, is now back on duty as chief maintainer — the gatekeeper who decides which additions and improvements to the kernel will make it into a given release. However, for the first time GKH will also be allowed to sign off on future kernels, said Torvalds. As Vaughan-Nichols described it: “Kroah-Hartman, who runs the stable kernel, will have a say on Linus’ cutting-edge kernel.” It’s even possible that Kernel tree authority may be extended to a third maintainer, said Torvalds.

The sharing of sign-off authority and the new Contributor Convenant Code of Conduct were bound to happen eventually but were accelerated by growing intolerance to Torvalds’ often abusive and insulting emails. Around the time that a New Yorker story reported on Torvalds’ online temper tantrums, Linus announced on Sep 16 that he was taking a leave of absence to “take time off and get some assistance on how to understand people’s emotions and respond appropriately.”

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Linus Torvalds

Even Torvalds realizes he can’t totally rewire his behavior in six weeks. In a rambling Sep. 27 email interview with BBC News, he said that he would “never be cuddly,” but hoped to at least “fake it until I make it.”

In today’s ZDNet story, Torvalds said he has a weekly meeting with a therapist, and he is using an email filter to help him catch problem language before hitting the send key. The filter is pretty basic, however, and it “might be expanded upon or modified as needed or as I come up with more esoteric swearing,” said Torvalds. In Edinburgh, he asked his fellow maintainers to alert him if he felt an email was out of line.



Greg Kroah-Hartman

Torvalds had no role in drafting the CoC, which calls for more civil discourse and behavior in the community. He told Vaughan-Nichols that he hoped that by setting a new tone in discussions, it would only have to be used as “a last resort.”

In response to recent proposals to amend the CoC to drop mention of specific targets of potential harassment ranging from gender identity to ethnicity to personal appearance, both Torvalds and Kroah-Hartman have suggested leaving the language alone for now. In his Linux 4.19 release announcement, GKH promoted the CoC as a means to ensure that “all people, developers and maintainers alike, will be treated with respect and dignity while working together…” The programming of this week’s Linux Foundation hosted ELCE and Open Source Summit events reinforced the message with sessions about best practices for increasing gender, ethnic, and other forms of diversity.

Although the CoC is much like similar codes that have been adopted by major tech companies and communities, some Linux developers of a more Libertarian bent have raged against it as being a chilling overstep by so-called SJWs (Social Justice Warriors) that aims to dictate politically correctness. In part, the backlash was a response to feminist developers like former USB 3.0 maintainer Sage Sharp (formerly Sarah Sharp) leading the charge against Torvalds’ email abuse, a resistance that dated back to 2013.

The non-binary Sharp has been joined by many others who have argued that even by the tech industry’s low standards, the Linux kernel community is an excessively abusive, male dominated culture that has excluded women and minoriteis. The critics are not accusing Torvalds of singling out any particular group in his email abuse, but rather of refusing to acknowledge the community’s lack of diversity while encouraging a hostile work environment that ultimately tends to ostracize newcomers.

For now, it seems, the never quite peaceful kingdom of Linux has patched things up. Despite growing embedded security problems, these are good times for Linux, with steadily increasing server and embedded market share. There’s even a slight boost in desktop Linux usage caused in large part by Google’s Linux-based Chrome OS platform, which is opening up to the greater Linux community. Even Microsoft is embracing open source and Linux, from its Azure Sphere IoT platform to its recent open sourcing of 60,000 patents via the Open Invention Network (OIN).

Linux, of course, is also behind Android, the world’s dominant mobile platform. It appears that Android’s dominance won’t be challenged so much by Apple or other Linux-based phone challengers, as it will by Google itself with its non-Linux Fuchsia OS.

Fuchsia may not be an entirely bad thing for Linux, or so GKH hinted in his Linux 4.19 announcement. “There is no other operating system out there that competes against us at this time,” wrote Kroah-Hartman. “It would be nice to have something to compete against, as competition is good, and that drives us to do better, but we can live with this situation for the moment :).”



Further information

Linux 4.19 is available for free download. More information may be found in the

Linux 4/19 KernelNewbies overview and the Linux 4.19 announcement.