Migration to Debian Bookworm and compiler updates for KernelCI

Hello,

I'm reaching out on behalf of the KernelCI project team to discuss our
current compiler setup and planned migration to Debian Bookworm.

As you may know, our compiler images are currently based on Debian
Bullseye, which is approaching its end of life in July 2024. We have
been testing using gcc-10, which has presented us with some recent
challenges, notably a significant bug that results in false positive
compilation errors (specifically, the -Werror memcpy issue in
security.c). This situation has prompted us to consider an urgent
migration to Debian Bookworm. Additionally, the migration is
necessitated by our requirement to upgrade to a newer Python version to
support KernelCI v2 development efforts.

However, before we proceed, we have a couple of pending questions that
we hope to get clarity on:

1) We've noticed that the minimal available version of clang on
https://apt.llvm.org/bookworm/dists/ is 15, whereas our current minimal
requirement for the Linux kernel compilation is clang-13.0.1
(https://www.kernel.org/doc/html/next/process/changes.html). How
critical is it to continue providing compile tests for clang-13 (and
potentially clang-14)? This information would be vital for us in
planning our compiler support strategy moving forward.

2) We are also considering migrating to gcc-12 and would like to
inquire if the CIP (Civil Infrastructure Platform) could provide their
endorsement for this move. Should there be any reservations about
transitioning to gcc-12, we would greatly appreciate development
support in building gcc-10 for Bookworm. In the interim, we would like
to inquire if it's acceptable to continue using our current gcc-10
images based on Bullseye until such a migration is feasible.

We believe that addressing these questions is crucial for our project's
progression and ensuring that we maintain a robust and reliable build
environment for the Linux kernel. We eagerly await your feedback and
any recommendations you may have regarding our migration plan and
compiler version support.

Thank you for your time and consideration.

Best regards,

Denys Fedoryshchenko