# 14. Contributing to Open MPI

There are many ways to contribute. Here are a few:

1. Subscribe to the mailing lists and become active in the discussions.

2. Obtain a Git clone of Open MPI’s code base and start looking through the code.

   Note

   Be sure to see the Developers guide for technical details about the code base and how to build it).

3. Report bug fixes to the main code base.

   - First, ensure the bug was not already reported by searching existing GitHub Issues.

   - If you’re unable to find an open issue addressing the problem, open a new one.

4. Submit bug fixes to the main code base.

   - Awesome! Open a new GitHub pull request with the patch.

     - Please submit bug fixes / new features on the `main` branch first, and then port them to the relevant release branch(es) after they have been accepted on `main`. See this section for more information.

   - Ensure the PR description clearly describes the problem and solution. If there is an existing GitHub issue open describing this bug, please include it in the description so we can track them together.

   - Be sure to see the Open source contributions section, below.

5. Submit feature enhancements and/or new components to the main code base.

   - Awesome! We love new ideas!

   - You might want to suggest your change on the devel mail list before you start writing code. The developer level technical information on the internals of Open MPI may also be useful for large scale features.

   - If you’re contributing a large new piece of functionality, that will be best viewed if you — or someone, anyone — is also stepping up to help maintain that functionality over time. We love new ideas and new features, but we do need to be realistic in what we can reliably test and deliver to our users.

   - Be sure to see the Open source contributions section, below.

6. Submit fixes and/or entirely new content to this documentation.

   - Docs are great! We always need help with documentation.

   - These docs are authored using ReStructured Text markup with the Sphinx rendering tool under the `docs/` directory in the repository. This means you can submit a pull request with your docs updates, just like you would for any Open MPI code contribution.

   - See this section and also this section for information about how to install Sphinx locally and some high-level logistical instructions on how to write these docs.

7. Provide testing resources:

   1. For Github Pull Request Continuous Integration (CI)

   2. For nightly snapshot builds and testing

## 14.1. Open source contributions

All code contributions are submitted as pull requests on the Open MPI GitHub repository.

Important

All commits must include a `Signed-off-by:` line, indicating the submitter’s agreement to the Open MPI Contributor’s Declaration.

### 14.1.1. Contributor’s Declaration

In order to ensure that we can keep distributing Open MPI under our open source license, we need to ensure that all contributions are compatible with that license. Put differently: we need to have an established intellectual property pedigree of the code in Open MPI. This means being able to ensure that all code included in Open MPI is free, open source, and able to be distributed under the BSD license.

Open MPI has therefore adopted requirements based on the signed-off-by process as described in Section 11 of the Linux kernel document on Submitting Patches. Each proposed contribution to the Open MPI code base must include the text `Signed-off-by:` followed by the contributor’s name and email address.

Pro tip

You can use the `-s` flag to the `git commit` command (i.e., `git commit -s ...`) to automatically add the appropriate `Signed-off-by:` line to your commit message.

The `Signed-off-by:` line is a developer’s certification that he or she has the right to submit the patch for inclusion into the project, and indicates agreement to the Developer’s Certificate of Origin:

> By making a contribution to this project, I certify that:

> 1. The contribution was created in whole or in part by me and I have the right to submit it under the Open MPI open source license; or

> 2. The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the Open MPI open source license (unless I am permitted to submit under a different license); or

> 3. The contribution was provided directly to me by some other person who certified (1) or (2) and I have not modified it.

> 4. I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project and the open source license(s) involved.

Proposed contributions failing to include the `Signed-off-by:` certification will not be accepted into any Open MPI code repository. The community reserves the right to revert any commit inadvertently made without the required certification.

Note

This policy prevents a situation where intellectual property gets into the Open MPI code base and then someone later claims that we owe them money for it. Open MPI is a free, open source code base. We intend it to remain that way.

If you have not already done so, please ensure that every commit in your pull request contains the `Signed-off-by:` line.

### 14.1.2. Git commit messages

Please write a good Git commit message, with a short first line describing what was done, and then a description of why it was done.

Pro tip

See this blog entry for an excellent description of how to write a good Git commit message.

### 14.1.3. Code style

There are a small number of style rules for Open MPI:

1. For all code:

   - 4 space tabs. No more, no less.

   - No tab characters at all. 2 indentations are 8 spaces — not a tab.

   - m4 code is a bit weird in terms of indentation: we don’t have a good, consistent indentation style in our existing code. But still: no tab characters at all.

2. For C code:

   - We prefer if all blocks are enclosed in `{}` (even 1-line blocks).

   - We prefer that if you are testing equality with a constant, put the constant on the left of the `==`. E.g., `if (NULL == ptr)`.

   - If there are no parameters to a C function, declare it with `(void)` (vs. `()`).

## 14.2. Closed source contributions

While we are creating free / open-source software, and we would prefer if everyone’s contributions to Open MPI were also free / open-source, we certainly recognize that other organizations have different goals from us. Such is the reality of software development in today’s global economy.

As such, it is perfectly acceptable to make non-free / non-open-source contributions to Open MPI. We obviously cannot accept such contributions into the main code base, but you are free to distribute plugins, enhancements, etc. as you see fit. Indeed, the the BSD license is extremely liberal in its redistribution provisions.