everything is a trade-off

Posted Aug 9, 2024 23:32 UTC (Fri) by dskoll (subscriber, #1630)
In reply to: everything is a trade-off by randomguy3
Parent article: A new kernel-version policy for Ubuntu

Sure, but why does a given Ubuntu release have to use the same kernel for its entire lifetime? What would be so bad about moving to a new kernel within a given release?

I run Debian Stable, but I build my own kernel packages using the latest upstream kernel (currently on 6.10.3) and nothing has broken for me so far.

everything is a trade-off

Posted Aug 10, 2024 0:59 UTC (Sat) by HenrikH (subscriber, #31152) [Link] (9 responses)

Now this is mostly relevant for the LTS release but when enterprise software and 3d party drivers are certified for say Ubuntu 22.04LTS that includes them being certified for the specific kernel version used by that version. Upgrading the kernel would require a new certification and that takes both time and money, most enterprises that I have worked with (banks and other companies in the finance industry) often only want to perform such a certification as seldom as possible and it takes months for them to perform it.

everything is a trade-off

Posted Aug 10, 2024 1:46 UTC (Sat) by Baughn (subscriber, #124425) [Link] (3 responses)

Isn’t the kernel changed during Ubuntu releases? I thought especially the LTSv releases used LTS kernels, which normally see a great deal of code churn during their lifetime.

everything is a trade-off

Posted Aug 10, 2024 7:30 UTC (Sat) by alspnost (guest, #2763) [Link] (2 responses)

No, LTS releases don't run LTS kernels. Ubuntu 24.04 should really have run with kernel 6.6, but instead they used kernel 6.8, which is long since EOL, so they have to keep patching it themselves. Upstream has abandoned it. But when 24.10 comes out, they'll make HWE packages for 24.04 based on the new kernel (which again, probably won't be an LTS. I'm assuming it'll be 6.11 but judging by this it might now be 6.12-rc....

everything is a trade-off

Posted Aug 10, 2024 14:05 UTC (Sat) by mathstuf (subscriber, #69389) [Link] (1 responses)

That could make the weird result of 23.10 having, say, 6.7 yet to get an LTS-on-LTS, 24.04 would *revert* to 6.6. Which is probably better for the LTS-ness, but is quite odd. I understand that the <even>.04-is-LTS is a nice indicator, but maybe some better planning could be involved…or LTS-ness is decided based on maintainability after a .1 rather than "happens to be released in a certain date pattern".

everything is a trade-off

Posted Aug 15, 2024 10:46 UTC (Thu) by sammythesnake (guest, #17693) [Link]

The downside of that would be that people who want an LTS kernel are generally the same people who value a predictable schedule for their next upgrade...

everything is a trade-off

Posted Aug 10, 2024 2:09 UTC (Sat) by dskoll (subscriber, #1630) [Link] (3 responses)

Sure, but if Ubuntu went with an RC kernel that subsequently had some large changes, you'd have the same problem.

everything is a trade-off

Posted Aug 10, 2024 10:38 UTC (Sat) by khim (subscriber, #9252) [Link] (1 responses)

Only if RC kernel would keep it's status as RC kernel for many months.

That's highly unusual situation, have that ever happened at all? I suspect some kernel releases could take 2 months from first RC1 to release but it's hard for me to imagine anything longer.

everything is a trade-off

Posted Aug 10, 2024 21:07 UTC (Sat) by intelfx (subscriber, #130118) [Link]

> That's highly unusual situation, have that ever happened at all? I suspect some kernel releases could take 2 months from first RC1 to release but it's hard for me to imagine anything longer.

That'll be "all kernels". There is either 7 or 8 -rcs for each kernel release.

everything is a trade-off

Posted Aug 10, 2024 16:32 UTC (Sat) by HenrikH (subscriber, #31152) [Link]

Highly unlikely, they talk about kernels in the rc4-5 stage in the linked article and as far as I can tall they are talking about choosing a rc during kernel freeze, not going release with a kernel in rc state.

everything is a trade-off

Posted Aug 12, 2024 8:46 UTC (Mon) by taladar (subscriber, #68407) [Link]

That sort of certification is basically the entire reason LTS distros lie about version numbers so heavily as if version x with dozens of backports wasn't just as much a new version as version x+1.

everything is a trade-off

Posted Aug 10, 2024 5:15 UTC (Sat) by wtarreau (subscriber, #51152) [Link] (1 responses)

> What would be so bad about moving to a new kernel within a given release?
> I run Debian Stable, but I build my own kernel packages using the latest upstream kernel (currently on 6.10.3) and nothing has broken for me so far.

Well, I'd say you've been lucky so far. I often face tiny breakage upon upgrade. It's always tiny stuff that scripts were relying on, such as a script that was checking for the battery state in /proc/acpi, iptables modules being reorganized and renamed, a network driver change which does not react similarly to tuning settings, a deprecated mount option that's no longer supported by a filesystem, etc. This is never too serious and often easily fixable once you understand what's happening. The thing is, users engage into LTS distros to benefit from fixes *without* having to deal with such trouble, and that's the deal. When users don't care about this, they just don't use LTS distros.

And there's of course the long list of possible regressions that come from feature improvements which you are not necessarily interested in but cause harm. When they render your system unbootable and hard too fix, the next time you'll simply skip the upgrade. This is not specific to the kernel but common to all software. There are branches which only receive fixes and that come with a much lower risk of regressions than branches getting new features and architectural changes, and users who validated a version don't want to break everything when just trying to apply a security fix.

everything is a trade-off

Posted Aug 10, 2024 14:39 UTC (Sat) by dskoll (subscriber, #1630) [Link]

OK, that makes sense. Thanks.

everything is a trade-off

Posted Aug 13, 2024 23:03 UTC (Tue) by montj2 (guest, #111739) [Link]

>> I run Debian Stable, but I build my own kernel packages using the latest upstream kernel (currently on 6.10.3) and nothing has broken for me so far.

I run this way as well. Matter o' fact, 6.10.4 is compiling in the background as I scroll LWN :)

everything is a trade-off

Posted Aug 15, 2024 10:43 UTC (Thu) by sammythesnake (guest, #17693) [Link]

When releasing a kernel that will be used by innumerable differing systems, there's a lot more that could go wrong compared to compiling a kernel for only one machine, so a degree of extra caution seems to make sense there...