Linus Torvalds and Dirk Hohndel, Open Source Summit North America 2024

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Hong Kong: At The Linux Foundation‘s Open Source Summit China conference, Linus Torvalds and his buddy Dirk Hohndel, Verizon’s Head of the Open Source Program Office, once more chatted about Linux development and related issues to the delight of their audience.  

As usual, the pair talked about the current state and future of the Linux kernel. In particular, their conversation touched on various aspects of Linux development, including the release process, security, Rust’s Linux integration, and the role of AI in software development.

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First, Torvalds is sorry to report that sched_ext, an extensible scheduler for building scheduling policies with eBPF, will not be included in the next Linux kernel release. He hopes, though, literally knocking on wood, that it will be in the forthcoming Linux 6.12 release.

Thinking about future releases, Hohndel asked Torvalds about his plans for the Linux kernel. Specifically, since at the current kernel release rate, “the Linux kernel 8.7 should come out about your 60th birthday, what do you see in it?” Torvalds replied, “I really don’t know.”

Torvalds continued that he he focuses on the shorter term. “The real development is about getting all the details right. And you don’t look five years ahead for that. You look one or two releases ahead.”

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Of course, Torvalds added, “Some features take longer than that. Later this year, we will have the 20th anniversary of the real-time Linux project. This is a project that literally started 20 years ago, and the people involved are finally at that point where they feel like it is done… well, almost done. They’re still tweaking the last things, but they hope it will soon be ready to be completely merged in the upstream kernel this year.”

At the same time, Torvalds mentioned that even though Linux is 33 years old now, “You’d think that all the basics would have been fixed long ago, but they’re not. We’re still dealing with basic issues such as memory management.” The work is never done.

These days, the Linux kernel’s development process has a highly structured and rhythmic beat. Despite its complexity, the process has become highly reliable over the years. Torvalds mentioned that while they aim for a release every nine weeks, it didn’t used to be that way. 

In the beginning, the process was very chaotic. Torvalds reminisces that when he first said he no longer wanted to do one major release every year or two but smaller releases every six weeks, everyone laughed at him. 

As for the release numbers, Torvalds reminded everyone yet again, they mean nothing. Hohndel said, “You typically change the major number around 19 or 20, because you get bored.” No, replied Torvalds, it’s because, “when I can’t count on my fingers and toes anymore it’s time for another ‘major’ release.”

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The pair then shifted gears into security. Hohndel brought up the huge number of Common Vulnerabilities and Exposures (CVE) in the Linux kernel. This isn’t because Linux is insecure. Torvalds replied, “Bugs will happen, and anything can be a security bug if somebody is clever enough to just figure out how to abuse it.”

Torvalds continued, “One reason why I stress that all security issues are just bugs is that there’s this tendency in the IT industry to treat security issues as something really, really, really special, and that actually ends up harming everybody.” 

So, what should you do about the constant weekly flow of Linux security bug fixes? Greg Kroah-Hartman, the maintainer of the Linux stable kernel, thinks you should constantly update to the newest, most secure stable Linux kernel. Torvalds agrees but can see the case for sticking with older kernels and relying on less frequent security patch backports. 

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Torvalds said, “There is some stability with old kernels, and we do backport for patches and fixes to them, but some fixes get missed because people don’t think they’re important enough, and then it turns out they were important enough.”

Besides, if you stick with an old kernel for too long when you finally need to update to a newer one, it can be a massive pain to do so. So, “to all the Chinese embedded Linux vendors who are still using the Linux 4.9 kernel,” Torvalds said, wagging his finger, “Stop.”

In addition, Hohndel said that when patching truly ancient kernels, the Linux kernel team can only say, “Sorry, we can’t help you with that. It was so long ago that we don’t even remember how to fix it.”

Switching to a more modern topic, the introduction of the Rust language into Linux, Torvalds is disappointed that its adoption isn’t going faster. “I was expecting updates to be faster, but part of the problem is that old-time kernel developers are used to C and don’t know Rust. They’re not exactly excited about having to learn a new language that is, in some respects, very different. So there’s been some pushback on Rust.”

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On top of that, Torvalds commented, “Another reason has been the Rust infrastructure itself has not been super stable.”

In general, Torvalds doesn’t care about newer technologies like the cloud and Kubernetes. “The only thing that matters is the kernel.” Hohndel rejoined, “That’s sure to be taken out of context!” 

Torvalds replied that he knows they are all very useful, but “clusters, clouds, and  Kubernetes are not an issue for me. The great thing about open source is that everyone specializes in what they’re interested in.”

The pair then moved on to the hottest of modern tech topics: AI. While Torvalds is skeptical about the current AI hype, he is hopeful that AI tools could eventually aid in code review and bug detection.

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In the meantime, though, Torvalds is happy about AI’s side effects. For example, he said, “When AI came in, it was wonderful, because Nvidia got much more involved in the kernel. Nvidia went from being on my list of companies who are not good to my list of companies who are doing really good work.”

Hohndel concluded the discussion by saying he’d used ChatGPT to come up with the top ten questions he should ask Torvalds. The first was, “How do you see the future of open-source software involved, especially with the rise of cloud services and proprietary software?”

Torvalds groaned and replied, “I never had a vision. I don’t want one. I see myself as a plodding engineer.” On that note, the interview ended to the crowd’s applause.