Backports of scx to older kernels

Work In Progress

The goal of this repo is to enable sched-ext binaries to build on kernels with older versions of the sched-ext source tree.

Dependencies

• Docker

How to use this repo

Setting up a backport

1. Create a branch named $SHORT_SHA-vmlinux , where $SHORT_SHA is the first 7 characters of the commit hash in the scx kernel tree you are targeting. In this branch, in .github/workflows/caching-build.yml, replace KERNEL_COMMIT_SHA7_HERE with the 7 character commit hash of the kernel commit you will be packporting to.

2. Run backport-scripts/generate-backport-vmlinux.sh passing it $SHORT_SHA (such as af1234) and branch name, in that order. Optionally, pass a third arg, the git repo to obtain that commit and branch from, if neccessary.

3. Update the symlink scheds/include/vmlinux/vmlinux.h to point to your new vmlinux.h.

4. Commit and push your branch.

5. Open a new branch (i.e. af1234-${SCX_RELEASE}-fixes) off of your initial branch (i.e. af1234) and edit files other than vmlinux.h until first cargo test (ran in this repo's root) passes and then CI passes. Edit .github/workflows/caching-build.yml as is neccessary to reducing the schedulers built/tested (not everything can be reasonably backported).

6. Push this branch as you get things working, push it as af1234-${SCX_RELEASE}-backport once CI passes.

7. Add a CI badge on this page on the setup-repo branch for the CI job for that new branch.

Updating a backport

1. Create a new -fixes branch from either a -vmlinux, -fixes branch or a -backport branch (whichever is closest to what you want).
2. Continue the instructions above from (4).

Updating this doc and the setup scripts.

Please make any updates to this document and the setup scripts on the branch setup-repo. This will be rebased atop main when merging in updates.

main will be updated periodically (roughly coinciding with releases of scx), backports will be updated/created on an as-needed basis. *main will be overwritten with commits from upstream during syncs. setup-repo will be rebased upon main and pushed to main before rebasing other branches, so put things to persist across this process on setup-repo.`