Git Commit messages
There are a number of different recommendations for git commit messages, so this is another one.
It’s expected that coreboot contributors already generally understand the idea of writing good git commit messages, so this is not trying to go over everything again. There are other tutorials that cover that.
Line length
The subject line should be <= 65 characters, with an absolute maximum of 75 characters
Prose in the commit message should be <= 75 characters
If reflowing prose to 75 characters can reduce the length of the commit message by 2 or more lines, please reflow it. Using the entire 75 characters on a line when reasonable is recommended, but not required.
Non-prose text in the body in the commit message does not need to be wrapped at 75 characters. Examples: URLs, compiler output, or poetry.
Both Subject & body
Use the present tense. (The for loop exits too early, so …”, not “The for loop exited too early, so …”).
When using acronyms, make sure they’re explained in the commit message itself or in the acronyms list.
Commit message Subject Line
Start the subject line with a prefix denoting the area of the change. Often part of the path can be used by that. Looking through existing commit messages summaries with
git log --oneline ...gives a good idea. Because this prefix takes space used by the rest of the subject, it should be kept short while still uniquely describing the area.Don’t include
src/Use abbreviations where possible:
mb: mainboard
vc: vendorcode
Don’t end the subject line with a period.
Use the imperative mood. (“Fix whitespace”, not “whitespace fixes”).
Commit Message Body
Make sure the problem being solved by the commit is described. While it may be obvious to the committer, it may not be obvious to others.
Reference other commits with either CB:XXXXX or a 10 character hash and the subject.
When using a URL in a commit message, use archive.org when possible. URLs often get changed or go stale, so this keeps them stable.
Make sure that all changes in a patch are addressed in the commit message.
A TEST= tag is highly recommended, but not required. This lets people know whether you tested it by booting the board or just by compiling.
All but the most trivial of patches should generally have a body.
A BUG= tag can be added when the author wants to indicate that the patch is or is not related to a bug. This can be either in coreboot’s issue tracker, or a private issue tracker.
BUG=b:####is used by the Google internal issue tracker.BUG=chromium:####indicates the Chromium public tracker at https://issues.chromium.org/BUG=CID ####can be used to indicate coverity error fixes.BUG=https://...can be used to link directly to a public tracker.
The BRANCH= tag is used in cases where a patch needs to be added to a specific downstream branch. This is never required by the coreboot project.