# Best practices

These are a few guidelines to keep in mind when submitting patches to libvirt: following them will maximise the chance of your patches being reviewed in a timely manner and being accepted into libvirt with minimal back-and-forth.

- Discuss any large changes on the mailing list first. Post patches early and listen to feedback.

- In your commit message, make the summary line reasonably short (60 characters is typical), followed by a blank line, followed by any longer description of why your patch makes sense. If the patch fixes a regression, and you know what commit introduced the problem, mentioning that is useful. If the patch resolves a upstream bug reported in GitLab, put "Fixes: #NNN" in the commit message. For a downstream bug, mention the URL of the bug instead. In both cases also summarize the issue rather than making all readers follow the link. You can use 'git shortlog -30' to get an idea of typical summary lines.

- Split large changes into a series of smaller patches, self-contained if possible, with an explanation of each patch and an explanation of how the sequence of patches fits together. Moreover, please keep in mind that it's required to be able to compile cleanly (including ninja test) after each patch. A feature does not have to work until the end of a series, but intermediate patches must compile and not cause test-suite failures (this is to preserve the usefulness of git bisect, among other things).

There is more on this subject, including lots of links to background reading on the subject, on Richard Jones' guide to working with open source projects.