Canonical has announced a change in its kernel strategy for Ubuntu development builds, as it plans to routinely package new upstream kernel releases — not only the kernel version its plans to use in the final, stable release.
How is this different to what went before?
Previously, development versions of Ubuntu would run on the same kernel the preceding stable release shipped with (at least for a significant chunk of the development cycle). It’d switch over to the target kernel version later in the cycle, usually ahead of Kernel Freeze.
That is what’s changing.
In its announcement, the Canonical Kernel Team states: “We aim now to deliver not only the latest kernel release by the end of the development cycle but also to provide, on a best-effort basis, kernel updates based on the intermediate Linux kernel upstream releases.”
I.e., Ubuntu 25.04 shipped with Linux 6.14, and Ubuntu 25.10 will use Linux 6.17. That makes versions 6.15 and 6.16 ‘intermediate’ releases. In the past, those would (usually) not be packaged or tested in daily or development builds. With this change, they will.
On the benefits, the team adds: “With this policy, we expect to find potential kernel-related issues earlier in the development cycle, leading to greater confidence in the quality of the final Ubuntu kernel version as we approach shipping the Ubuntu GA image.”
This new policy will take effect for the development of Ubuntu 25.10 ‘Questing Quokka’ and, according to the Ubuntu kernel team, a build based on the Linux 6.15 kernel is already available for testing, with work underway to package Linux 6.16 kernel in the coming weeks.
A Continuous Kernel Testing Cadence
Last year, Canonical committed to using the latest available kernel in new Ubuntu releases, even if that kernel version is only in release candidate status.
The plan for Ubuntu 25.10 to use Linux 6.17, a version which just opened for development following the Linux 6.16 release, is a result of that change, and benefits users on Ubuntu 24.04 LTS who will get Linux 6.17 as a back port via a HWE update early next year.
This latest kernel policy change jives neatly with Ubuntu’s new monthly snapshots. Those were created to (among other reasons) help uncover compatibility issues and bugs earlier in the development cycle through greater use of automated testing.
A commitment to shipping interim kernel releases in those builds helps create a kind of continuous cadence for constant testing, which should help to ensure the final kernel selected (and the release it ships in) are as solid as possible.
Plus, for the first time, it will make testing new upstream kernels on Ubuntu as easy as downloading a daily build or monthly snapshot. This removes the need to rely on third-party PPAs or untrusted repos for those who want to test new kernel features on their hardware.