Suggestion: Please consider shipping Ubuntu 18.04 LTS with Linux Kernel 4.16

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Linux Kernel 4.16 will include refinements to the Meltdown/Spectre patches, and those refinements will almost certainly need to be backported to 4.15.

Kernel 4.16 will likely be released in early April, ahead of the “kernel freeze” for Bionic Beaver, which is currently set for April 12th.

Given that shipping with 4.16, instead of 4.15, would obviate the need for backporting (and maintaining) the refined Meltdown/Spectre patches, and given that Linus Torvalds hopes that “we’ll have a normal and entirely boring release cycle for 4.16” (the 4.15 release cycle was unusual in so many (bad) ways), I feel it’s better to aim for 4.16. “Because boring really is good.”

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The Ubuntu kernel team of course are more aware of upcoming changes than most of us :slight_smile:

I’m not sure what their policy is, but given 18.04 is an LTS (long term support) release, we may be required to choose a kernel that also has “longterm” support, such as 4.14 (https://www.kernel.org/).

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As of December 6, 2017, the Ubuntu Kernel Team was “tentatively planning to converge on 4.15 for the Bionic Beaver 18.04 LTS release.” And I haven’t read anything indicating that those plans have changed.

Yes, of course they know much better than most of us. Nonetheless, I hope that the matter will be discussed here, in the open, before a final decision is made.

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If kernel 4.16 come with Ubuntu 18.04, I will be the most exciting one, definitely. I got my new laptop shipped with Raven Ridge APU recently, which will not work well with kernel before 4.15, and of course kernel 4.16 should support this APU much better.

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4.15 made it to -proposed last week, I’ve been using it since then. So I would assume the ‘tentative plan’ is a bit more solid that it was in December.

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Yep, I know. By referencing the post from December of year, I was attempting to demonstrate that the Kernel Team has been planning for 4.15 for a long time, and that their plan doesn’t seem to have changed.

But that plan was devised before the 4.15 release cycle had become “unusual in so many (bad) ways” according to Linus.

With regard to 4.16-rc1, Linus wrote:

I don’t want to jinx anything, but things certainly look a lot better than with 4.15. We have no (known) nasty surprises pending, and there were no huge issues during the merge window. Fingers crossed that this stays fairly calm and sane.

So, given that the 4.15 release cycle was “unusual in so many (bad) ways,” given that the refinements to the Meltdown/Spectre patches in 4.16 will almost certainly need to be backported to 4.15, and given that Linus expects relatively smooth sailing for 4.16, I hope that the Kernel Team will at least attempt to ship with 4.16 instead of 4.15.

Sure, in the hurry to ship with 4.16, a few kernel bugs may be missed before release. But anyone who really needs stability will wait for 18.04.1 anyway.

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ok - wasn’t sure, so hence my reply :slight_smile:

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I…don’t think that is the right approach to take xD 18.04 should be stable on release (though I know the Software Updater doesn’t prompt upgrade from 16.04 and 14.04 until 18.04.1 is out). I guess the kernel team need to work out if they have enough time before kernel freeze to get any necessary testing and fixes for 4.16 in.

Not sure how that fact is relevant?

They might just choose to backport the Meltdown and Spectre fixes from 4.16 and they may be OK with that idea, we’ll see. If people want the new kernel they can grab it themselves?

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The development cycle for kernel 4.15 was a clusterf*#k. On the other hand, kernel 4.16 is expected to have a smooth development cycle.

Simply put, given a choice, Ubuntu 18.04 LTS should be based on a kernel having a smooth development cycle, and not based on a kernel having a clusterf*#k of a development cycle.

Yes, that’s exactly what I’m afraid that they will do. Backports don’t come without risks. What’s more, the backports will need to be maintained for five years (to support those not on HWE).

So, given that 4.16 will have been released before the Ubuntu kernel freeze (April 12th), it would make absolutely no sense to release Ubuntu with 4.15 and then backport the Meltdown and Spectre fixes from 4.16 into 4.15.

The Kernel Team can track the kernel release candidates. By about 4.16-rc5 (expected mid-March), the rc kernel should be fairly stable, which should provide the Kernel Team enough time to work out most wrinkles (and apply the fixes to final 4.16) before the release of Ubuntu 18.04.

But even if they miss a few bugs before the release of Ubuntu, no big deal. The Kernel Team always misses a few bugs before an Ubuntu release. That is, whether they go with 4.15 or 4.16, bugs will need to be fixed after the release. Better to fix them in 4.16 (smooth) than to fix them in 4.15 (clusterf*#k).

Of course they can. But as you point out, this will be an LTS for Ubuntu. An LTS release shouldn’t be based on kernel that had one of the most chaotic development cycles in recent Linux history.

Kernel 4.15 will have lots of baggage and should be avoided. Rather than carry that baggage for the next five years, better to wait for 4.16. Or if waiting isn’t possible, then I suggest releasing Ubuntu 18.04 LTS with kernel 4.14, which, although also needing Meltdown and Spectre fixes from 4.16, at least will receive them as a part of LTS kernel support.

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Given the addition of more Spectre and Meltdown patches to kernel 4.16 (which will need to be backported to 4.15), and given that the 4.16 dev cycle “continue[s] to be pretty normal” (compared to 4.15), I continue to hope that Ubuntu 18.04 LTS will be released with kernel 4.16 instead of kernel 4.15.

Why would Ubuntu want to support kernel 4.15 (procreated during an unholy clusterf#ck of a dev cycle, and already requiring significant Spectre and Meltdown backports) in an LTS, when kernel 4.16 will almost certainly be released well before the “kernel freeze” for Bionic Beaver, which is set for April 12th?

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Linux 4.16 was released earlier today. I’ve installed it onto Bionic Beaver from kernel-ppa/mainline, and so far, I haven’t noticed any adverse issues on my system.

While I realize that it is increasingly less likely that Ubuntu 18.04 LTS will ship with Linux 4.16, I do hope that the devs will at least test kernel 4.16 before the “kernel freeze” for Bionic Beaver, which is set for April 12th. And who knows, if those tests go well, maybe Ubuntu 18.04 LTS will ship with 4.16, instead of 4.15.

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As far as I know, the Ubuntu Kernel Team isn’t really using this website. If you want them to hear you, you should try contacting them a different way.

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I suspect the email on this link is the one that people will want to use. Alternatively the kernel IRC.

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@jbicha and @ads20000,

Thanks much for your suggestions. I send an email to the Kernel Team, which you can see here.

As I mentioned in the email, although I realize that it is unlikely that Ubuntu 18.04 LTS will ship with kernel 4.16, I do help that the Kernel Team will at least consider the possibility (if they haven’t done so already).

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UPDATE: According to this email, not surprisingly, Ubuntu 18.04 LTS will be shipping with kernel 4.15, and not with kernel 4.16.

For those who still want to test kernel 4.16 (unsupported) on Bionic, it is available for manual installation from kernel-ppa/mainline. And installation instructions are available here.

I’ve installed kernel 4.16 onto two very different systems running Bionic, and so far, I haven’t noticed any adverse issues on either system. Of course, your experience may be different.

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