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30 May 2012, 17:06

Enforcing the GPL – Kernel hackers join the fight

By Richard Hillesley

The Samba Team and seven kernel hackers have come together with Software Freedom Conservancy to help efforts to ensure compliance with the GPL by those who implement Linux and other GPL software. Richard Hillesley talked to Bradley Kuhn of Software Freedom Conservancy, Jeremy Allison of Samba, and Matthew Garrett, who works in his spare time with the GPL Compliance Project for Linux Developers.

A few months ago, in response to a posting by Matthew Garrett, issues around the enforcement of the GPL became the focus of a couple of articles on Linux Weekly News (LWN); Garrett had urged Linux kernel copyright holders to get involved in GPL enforcement.

Garret's initiative and the debate that followed have resulted in the Samba team and a number of Linux kernel developers coming together to employ the services of Software Freedom Conservancy (SFC) to enforce their copyrights, alongside other projects such as Evergreen, Inkscape, Mercurial, Sugar Labs, and Wine.

In the past, the Conservancy has dealt with GPL violations almost exclusively through BusyBox, which is a toolbox of utilities for embedded systems and describes itself as "the Swiss Army Knife of Embedded Linux". This worked well because BusyBox is a ubiquitous presence on embedded Linux systems and the BusyBox developers are enthusiastic upholders of the GPL, but this also led to some misconceptions about the nature of GPL compliance, as well as calls for a BusyBox replacement project, using a more liberal open source licence.

Bradley Kuhn, who runs Software Freedom Conservancy, was keen to address the issue and show that BusyBox is not "the only project that cares about the requirements of GPL", and that "developers who have picked GPL have done so for a reason. There is always a core contingent in any copylefted project that wants to see the licence complied with", he says. "If a software program says its licence is GPL there is sure to be some developer who has contributed who will want to make sure the licence is respected."

So far, he has "gone about the process of recruiting Linux developers in an ad hoc fashion. I reached out to a few Linux developers in a haphazard way and asked if they'd like to be involved"; he believes that others will join as the process becomes better known.

Matthew Garrett's rationale for getting involved is that "compliance isn't about punishing companies. It's about encouraging them to fulfil their licence obligations", and that "increasing SFC's code coverage means they can make a more convincing argument, and I'd expect companies to pay attention to that."

"The kernel is the fundamental component of Linux-based devices", he says. "Android has been designed to use as little GPLed code as possible, and what we've been seeing recently is that companies have been trying to get rid of even more GPLed components in order to reduce their obligations. Obtaining compliance is easier if you have copyright holders involved, and if the only GPLed component on a system is the kernel then that means getting kernel hackers involved."

Give and take

Free software issued under the GPL makes a simple pact between the coder and the user. Anyone can take, modify, copy, share and redistribute the software and the code, but must pass on the same rights to subsequent users of the software, including any modifications to the code.

The coder, who is usually, but not always, the copyright holder, gains because enhancements to the code are fed back through the development process. The user gains because the code remains free and the obligation is mutual, meaning that every other user has the same obligation to feed their changes back. The obligation to make code available is triggered when a user distributes the code or binary compiled versions of the code.

The best illustration of how this works is the Linux kernel. Linux and free software have radically transformed the way in which software development is approached by the computer industry. Organisations as diverse as Red Hat, Intel, Sony, NASA, and IBM have contributed their ideas and software under the GPL, and actively participate in the development of Linux in the knowledge that the other companies are also making contributions, which works to their mutual benefit, the benefit of their customers, and the wider benefit of the community.

Their motives have not always been altruistic, but the effect has been the same. They have shared their code, and this has changed the way in which ideas and information are viewed and shared between organisations and individuals. Companies participate because it works. Individuals participate for a multiplicity of reasons. But the continued evolution, efficiency and quality of the kernel has been dependent upon the voluntary (or sponsored) contribution of thousands of programmers who have submitted large and small patches, and were able to do so because they had access to the code, and to all the changes made to the code.

Sharing the code is useful to everyone, but the application of copyleft depends upon the willingness of distributors of GPLed software to comply with the terms of the licence, and/or the willingness of copyright holders to act in defence of the GPL. The licence hasn't always been enforced, because the copyright holders have had other things to do, or, because the copyright has been assigned to corporate entities who don't care about the licence beyond their immediate needs. So the participation in GPL enforcement of significant contributors to the kernel is an important development.

Next: A level playing field

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