One of Linux's elder statesmen has published an essay about combining proprietary software with GPL-licensed software (such as the Linux kernel) in devices. Focusing on the specific example of mobile phones, Perens offers advice both about what to do and what not to do.

Perens begins by noting that most legal disputes over the GPL so far have involved devicemakers. He suggests that in many cases, the smaller product companies that create Linux device firmware fail to inform their clients about the ongoing responsibilities of using GPL-licensed code (such as distributing the license with the product, and making source code available on request).

On Perens' to-do list for would-be GPL software users are:

• Build a partnership of your legal organization and engineering
• Legal-engineering reviews need to happen early

On his don't-do list are:

• Don't assume binary drivers are safe — they're untested legally
• Don't look for loopholes to exploit in open source licenses

In between, Perens examines mobile phones, in specific. He suggests that:

• Phone vendors should rally around a common GSM baseband modem stack with a shared license. Currently, they spend “billions” to maintain stacks separately, despite the fact that little if any product differentiation occurs within the stack.
• The dual-processor architecture used in most phones allows a clean separation of proprietary code (such as DRM, the GSM stack) and open source software — even GPL3-licensed software
• Virtualization is another approach to separating proprietary and open source code, even when run on a single processor. However, virtualization systems are “probably too large” for embedded applications, Perens says.

Bruce Perens has done so much for Linux — from creating Busybox (the number one embedded Linux utility) to helping establish Debian (the most popular Linux distribution) in its formative years — that it's difficult to encapsulate him in a biography. So, I'll defer to his Wikipedia page.

Perens's essay, “Combining GPL and proprietary software,” can be found here.

 
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