GNU Radio Enhancement Proposal Process

By Martin Braun | February 13, 2018

The GNU Radio Enhancement Proposal Process

One thing that has been missing in the GNU Radio development process has been a transparent way to contribute, to see what people are working on, and to coordinate development between people developing new features for GNU Radio. To facilitate all of this, we’ve introduced the GREP process.

The process was announced on February 5, 2018, on discuss-gnuradio. Here’s the  announcement:

Subject: [Discuss-gnuradio] Introducing the GREP process Date: Mon, 5 Feb 2018 12:42:19 +0100 From: Martin Braun <>

Hi all,

in order to facilitate the development of GNU Radio, we will be launching something new for GNU Radio: The GREP process. You may have guessed it… GREP stands for “GNU Radio Enhancement Proposal”.

If you want to take a look at what we’ve published so far, go here:

…but I’ll be going a bit into the motivation in the following. You might want to read this first.

Other projects have done this for a while now; most famously, the Python project has the PEP process, from which we took heavy inspiration for the GREP process.

What is this good for?

For GNU Radio feature development, we currently lack a way of planning new features before any kind of development starts. For small things, such as adding a specific API call to a block, people can simply submit a “Feature Request” on github. However, there’s no path forward, other than hoping that someone will pick up the work and implement it, there’s no way of knowing what’s happening with a feature request.

It’s much worse for big changes. Any maintainers second largest fear (after the fear of no one contributing) is the fear that someone submits a many-thousand line pull request out of the blue. Worst case scenario is when the maintainer needs to reject the pull request, and some enthusiastic developer just wasted weeks or months of work.

For big feature development, we need a way to plan development and coordinate it between contributors, maintainers, and lead developers. This is the first big reason to introduce GREPs: They are a platform for discussing feature development, publicly, ahead of time.

GREPs are so much more, though. They give us a tool to codify things such as coding guidelines, but with a clear way of putting them up for discussion. And they don’t have to be technical; enhancement proposals to the GNU Radio organization itself can also become GREPs. We distinguish between GREPs that are technical enhancements, organizational changes, and informational documents.

How does this affect me?

As you can imagine, we GNU Radio developers discuss things among each other all the time. But do you know what we’re talking about? Probably not. We don’t even use electronic media all the time, because many of us know each other personally, and we can just chat face to face. That’s nice sometimes, but it’s not transparent. GREPs are designed to change that: Major technical or other discussions can now be publicly viewed, and participation is highly encouraged. Say Marcus and Andrej are planning changes to the testing system, they can write it up and post it on github. If you’re a user that happens to be affected by the changes, you can go ahead and participate in the discussion before changes take effect, and use that opportunity to contribute to the code base in a way that is beneficial for you or your organization.

Even if you’re not affected, you might be interested to see where the project is going. As major changes shall become GREPs before they become code, you can extrapolate future development and plan accordingly.

In other cases, we will submit GREPs that explain the way we do things, such as coding guidelines. Having such documents in one place (i.e., the GREP repository) will make it easier for you to understand rules and conventions used in the project.

How do GREPs work?

GREPs are numbered, and GREP 0 is the GREP that explains the GREP process itself, so I encourage you to go ahead and read it. In a nutshell, suggestions are written down in a markdown document, and a pull request is made to the GREP repository. Merging the pull request means that the GREP meets formal criteria and is now open for discussion (it does not mean the GREP is accepted for implementation).

Find GREP 0 here:

I have suggestions for improving the GREP process, now what?

That’s fine – in fact, it’s built into the GREP process itself. Truth be told, we are assuming that we’ll need to tweak and polish the process for a while until we get into its final form (or maybe it’ll never reach a final form, as requirements keep changing). So go ahead and submit issues on the GREP issue tracker, and we’ll have a discussion about them. Ultimately, it’ll be up to core GNU Radio devs to decide whether or not we accept your suggestions for change, but since we don’t know what the perfect GREP process looks like yet, we’re very interested to hear any kind of feedback.

Which GREPs are in the pipeline, and how do I get updates?

If you have a github account, you can track the state of the greps repository and receive notifications. But of course, we’ll be talking about it on the mailing list, too. We very strongly encourage submitters of GREPs to discuss them on the mailing list before submitting a pull request anyway.

As for immediate future GREPs, we’ll be writing down coding guidelines as one of the next GREPs, as well as any other changes to the development model that we plan to implement. Given the recent change in maintainership, this is good timing to implement such documents.

Other than that, we have a few ideas for features and changes that will become GREPs, but just keep an eye open for those.

Martin Braun