Making Changes Using Git
The Apache NuttX project uses the Git version control system to track changes, and the source code is hosted on GitHub.
If you want to make changes to NuttX, for your own personal use, or to submit them back to project to improve NuttX, that’s easy. For the purposes of this guide, you’ll need a GitHub account, since the Apache NuttX team uses GitHub. (You could also use git locally, or save your changes to other sites like GitLab or BitBucket, but that’s beyond the scope of this guide).
Here’s how to do it:
Set your git user name and email
$ cd nuttx/ $ git config --global user.name "Your Name" $ git config --global user.email "yourname@somedomaincom"
Sign in to GitHub
If you don’t have a GitHub account, it’s free to sign up.
Fork the Projects
Visit both these links and hit the Fork button in the upper right of the page:
Clone the Repositories
On the GitHub web page for your forked
nuttxproject, copy the clone url – get it by hitting the green
Clone or Downloadbutton in the upper right. Then do this:
$ git clone <your forked nuttx project clone url> nuttx $ cd nuttx $ git remote add upstream https://github.com/apache/nuttx.git
Do the same for your forked
$ cd .. $ git clone <your forked nuttx-apps project clone url> apps $ cd apps $ git remote add upstream https://github.com/apache/nuttx-apps.git
Create a Local Git Branch
Now you can create local git branches and push them to GitHub:
$ git checkout -b test/my-new-branch $ git push
Git Workflow With an Upstream Repository
The main NuttX git repository is called an “upstream” repository - this is because it’s the main source of truth, and its changes flow downstream to people who’ve forked that repository, like us.
Working with an upstream repo is a bit more complex, but it’s worth it since you can submit fixes and features to the main NuttX repos. One of the things you need to do regularly is keep your local repo in sync with the upstream. I work with a local branch, make changes, pull new software from the upstream and merge it in, maybe doing that several times. Then when everything works, I get my branch ready to do a Pull Request. Here’s how:
Fetch upstream changes and merge into my local master:
$ git checkout master $ git fetch upstream $ git merge upstream/master $ git push
Merge my local master with my local branch:
$ git checkout my-local-branch $ git merge master $ git push
Make changes and push them to my fork
$ vim my-file.c $ git add my-file.c $ git commit my-file.c $ git push
Repeat 1-3 as necessary
tools/checkpatch.shscript on your files
When your code runs, then you’re almost ready to submit it. But first you need to check the code to ensure that it conforms to the NuttX C Coding Standard. The
tools/checkpatch.shscript will do that. Here’s the usage info:
$ ./tools/checkpatch.sh -h USAGE: ./tools/checkpatch.sh [options] [list|-] Options: -h -c spell check with codespell(install with: pip install codespell -r range check only (used with -p and -g) -p <patch list> (default) -g <commit list> -f <file list> - read standard input mainly used by git pre-commit hook as below: git diff --cached | ./tools/checkpatch.sh -
Run it against your files and correct all the errors in the code you added, so that
tools/checkpatch.shreports no errors. Then commit the result. For example:
$ ./tools/checkpatch.sh -f my-file.c arch/arm/src/sama5/hardware/my-file.c:876:82: warning: Long line found $ # fix errors $ vim my-file.c $ # run again $ ./tools/checkpatch.sh -f my-file.c
If you have made a lot of changes, you can also use this bash commandline to see the errors for all the changed C files in your branch (assumes you are currently on the branch that has the changed files):
$ git diff --name-only master | egrep "\.c|\.h" | xargs echo | xargs ./tools/checkpatch.sh -f | less
Note that there are some bugs in the
checkpatch.shuses, so it may report a few errors that are not actually errors. The committers will help you find these. (Or view the nxstyle Issues.)
Commit the fixed files
$ git add my-file.c $ git commit my-file.c $ git push
Submitting Your Changes to NuttX
Pull requests let you tell others about changes you’ve pushed to a branch in a repository on GitHub. Once a pull request is opened, you can discuss and review the potential changes with collaborators and add follow-up commits before your changes are merged into the base branch.
(from GitHub’s About pull requests page)
Before you do a Pull Request, the NuttX team will usually want all the changes you made in your branch “squashed” into a single commit, so that when they review your changes, there’s a clean view of the history. If there are changes after Pull Request review feedback, they can be separate commits. Here’s the easiest way I found to do that initial squash before submitting the Pull Request:
Check out my branch
$ git checkout my-branch
Fetch the upstream code
$ git fetch upstream
Rebase onto the upstream code
$ git rebase upstream/master
Push to your remote
This needs to a force push with
$ git push -u my-branch -f
Create a GitHub Pull Request
A Pull Request is how you ask your upstream to review and merge your changes.
Get Pull Request feedback and implement changes
Get suggestions for improvements from reviewers, make changes, and push them to the branch. Once the reviewers are happy, they may suggest squashing and merging again to make a single commit. In this case you would repeat steps 1 through 6.
How to Include the Suggestions on Your Pull Request?
If you submitted your first PR (Pull Request) and received some feedbacks to modify your commit, then probably you already modified it and created a new commit with these modifications and submitted it.
Also probably you saw that this new commit appeared on your Pull Request at NuttX’s github page (at Commits tab).
So, someone will ask you some enigmatic thing: “Please rebase and squash these commits!”
Basically what they are saying is that you need to update your repository and fuse your commits in a single commit.
Let walk through the steps to do it!
Move to upstream branch and pull the new commits from there:
$ git checkout upstream $ git pull
Return to your working branch and rebase it with upstream:
$ git checkout my-branch $ git rebase upstream
If you run git log will see that your commits still there:
$ git log commit xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (HEAD -> firstpr, upstream/master, upstream) Author: Me Myself Date: Today few seconds ago Fix suggestions from mainline commit xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Author: Me Myself Date: Today few minutes ago Initial support for something fantastic commit 6aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa Author: Xiang Xiao <firstname.lastname@example.org> Date: Sun Dec 18 00:00:00 2022 +0800 Some existing commit from mainline
See, you have two commits (Fix suggestions… and Initial support…), we can squash both in a single commit!
You can use the git rebase interactive command to squash both commits:
$ git rebase -i HEAD~2
Note: case you had 3 commits, then you should replace HEAD~2 with HEAD~3 and so on.
This command will open the nano editor with this screen:
pick 10ef3900b2 Initial support for something fantastic pick 9431582586 Fix suggestions from mainline # Rebase 9b0e1659ea..9431582586 onto 9b0e1659ea (2 commands) # # Commands: # p, pick <commit> = use commit ...
Here you can control the actions that git will execute over your commits.
Because we want to squash the second commit with the first you need to replace the ‘pick’ of the second line with a ‘squash’ (or just a ‘s’) this way:
pick 10ef3900b2 Initial support for something fantastic squash 9431582586 Fix suggestions from mainline # Rebase 9b0e1659ea..9431582586 onto 9b0e1659ea (2 commands) # # Commands: # p, pick <commit> = use commit ...
Now just press Ctrl + X to save this modification. In the next screen you can edit your git commit messages. After that press Ctrl + X again to save.
If you run git log again will see that now there is one a single commit:
$ git log commit xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (HEAD -> firstpr, upstream/master, upstream) Author: Me Myself Date: Right now baby, right now Initial support for something fantastic This commit includes the suggestions from mainline commit 6aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa Author: Xiang Xiao <email@example.com> Date: Sun Dec 18 00:00:00 2022 +0800 Some existing commit from mainline
Just push forced this new commit to your repository:
$ git push -f
Now you can look at your PR at NuttX’s github to confirm that this squashed commit is there.
NuttX Code Contribution Workflow (draft) – All the details are here if you need them!