Re: Information About The Linux Kernel Maintenance In Debian
Thanks Mortiz and Maximilian for your answers. Very useful! On Sat, May 27, 2023 at 02:19:44PM +0200, Moritz Mühlenhoff wrote: Hi Federico! I'm a CERN employee currently evaluating Debian as a possible solution for our systems in use to control particle accelerators. I would like to know more about how the Debian community handles the Linux kernel integration. In particular, I can't easily find the following information: Cool, if you have more specific followup questions, don't hesitate to ask. - Criteria to select a kernel version for a Debian release. It looks to me you are following LTS releases, but as you know kernel LTS is a moving target in terms of duration. So, how you choose? Debian releases happen every two years at approximately the end of the second quarter of uneven years. kernel.org LTS releases are usually announced/picked by end of each calendar year and the latest kernel.org LTS gets picked as the kernel version for Debian. Debian 9 has 4.9.x, Debian 10 had 4.19.x, Debian 11 and 5.10 and Debian 12 will have 6.1. - How much a Debian kernel diverges from kernel.org release overtime? Not much, you can have a look yourself for the current patches applied to the 6.1.27 kernel which will be part of the initial Debian 12 release (and future updates will rebase to 6.1.x LTS releases): https://salsa.debian.org/kernel-team/linux/-/tree/sid/debian/patches Anything in bugfix are cherrypicked bugfixes, debian/ contains a small set of Debian-specific patches (for narrow toolchain or software freedom issues) and feature contains a small set of backports (e.g. currently for improved support for some non-x86 systems). In the past that also included backported support for some NICs or RAID controllers (but these usually only appear later in a release cycle). - I see you explain how to build and run any kernel from kernel.org, but I do not see and discouragement in doing so. Is this because you do not see any known incompatibilities ? Generally running a patched or bespoke kernel is supported. It's mostly a matter of people power to do it properly (since one needs to rebase to security updates and applying custom patches might need rebases if underlying kernel code for updated). Some parts of the OS (e.g. systemd) expectsa given set of kernel features to be present to operate properly, but usually these are quite common and unlikely to be absent in custom configs anyway. If you start with the current Debian kernel config as a base (found under /boot/config-VERSION) you won't run into any surprises. Cheers, Moritz -- Federico Vaga - CERN BE-CEM-EDL
Re: Information About The Linux Kernel Maintenance In Debian
Hi Federico! > I'm a CERN employee currently evaluating Debian as a possible solution for our > systems in use to control particle accelerators. I would like to know more > about > how the Debian community handles the Linux kernel integration. In particular, > I > can't easily find the following information: Cool, if you have more specific followup questions, don't hesitate to ask. > - Criteria to select a kernel version for a Debian release. It looks to me you >are following LTS releases, but as you know kernel LTS is a moving target > in >terms of duration. So, how you choose? Debian releases happen every two years at approximately the end of the second quarter of uneven years. kernel.org LTS releases are usually announced/picked by end of each calendar year and the latest kernel.org LTS gets picked as the kernel version for Debian. Debian 9 has 4.9.x, Debian 10 had 4.19.x, Debian 11 and 5.10 and Debian 12 will have 6.1. > - How much a Debian kernel diverges from kernel.org release overtime? Not much, you can have a look yourself for the current patches applied to the 6.1.27 kernel which will be part of the initial Debian 12 release (and future updates will rebase to 6.1.x LTS releases): https://salsa.debian.org/kernel-team/linux/-/tree/sid/debian/patches Anything in bugfix are cherrypicked bugfixes, debian/ contains a small set of Debian-specific patches (for narrow toolchain or software freedom issues) and feature contains a small set of backports (e.g. currently for improved support for some non-x86 systems). In the past that also included backported support for some NICs or RAID controllers (but these usually only appear later in a release cycle). > - I see you explain how to build and run any kernel from kernel.org, but I do >not see and discouragement in doing so. Is this because you do not see any >known incompatibilities ? Generally running a patched or bespoke kernel is supported. It's mostly a matter of people power to do it properly (since one needs to rebase to security updates and applying custom patches might need rebases if underlying kernel code for updated). Some parts of the OS (e.g. systemd) expectsa given set of kernel features to be present to operate properly, but usually these are quite common and unlikely to be absent in custom configs anyway. If you start with the current Debian kernel config as a base (found under /boot/config-VERSION) you won't run into any surprises. Cheers, Moritz
Re: Information About The Linux Kernel Maintenance In Debian
Dear Federico, > can't easily find the following information: > > - Criteria to select a kernel version for a Debian release. It looks to me you > are following LTS releases, but as you know kernel LTS is a moving target in > terms of duration. So, how you choose? this depends on the Debian release cycle, which the Debian release team sets. This is announced in the debian-release mailing list. Once the release date cycle are known, the Debian kernel team tries to optimise to have a recent enough LTS release balanced with conservative exposure to enough hardware. > - How much a Debian kernel diverges from kernel.org release overtime? The stable kernel does not in general add hardware backports. The amount in debian depends on the vested interests. If we get enough bug reports or someone making it easy in gitlab to merge newer hardware support that happens too. The driver has to be released in mainline to qualify. > - I see you explain how to build and run any kernel from kernel.org, but I do > not see and discouragement in doing so. Is this because you do not see any > known incompatibilities ? For security maintenance we encourage to use the Debian one. Of course if you have in house capabilities to follow whatever LTS release you choose there will not be trouble (unless you set HZ to some funny value or disable features glibc assumes). We did optimize certain architectures for size but due to the involved time constraints this got dropped. Hope this helps, do not hesitate to follow-up. Thank you for your interest (: maximilian
Information About The Linux Kernel Maintenance In Debian
Dear kernel maintainers, I'm a CERN employee currently evaluating Debian as a possible solution for our systems in use to control particle accelerators. I would like to know more about how the Debian community handles the Linux kernel integration. In particular, I can't easily find the following information: - Criteria to select a kernel version for a Debian release. It looks to me you are following LTS releases, but as you know kernel LTS is a moving target in terms of duration. So, how you choose? - How much a Debian kernel diverges from kernel.org release overtime? - I see you explain how to build and run any kernel from kernel.org, but I do not see and discouragement in doing so. Is this because you do not see any known incompatibilities ? Thanks :) -- Federico Vaga
