Understanding Installation Requirements in GPLv2
byon March 25, 2021
According to our Principles, we always begin discussions with GPL violators privately. Many of these discussions are ongoing at any time. Recently, we received many questions about GPLv2's requirements regarding installation of modified versions of GPLv2'd software on the device on which the software was distributed. GPLv2 was drafted in anticipation of future uses of the software, and includes specific license text regarding installation:
The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable.
Unfortunately, we find that GPL violators often ignore (sometimes inadvertently) this part of that license text, which has always been of great importance: “the scripts used to control … installation of the executable”.
When a system is 100% FOSS “by design”, meeting this requirement is easy. We applaud the many community-oriented commercial projects that build their own hardware and give their users complete software freedom, such as the LulzBot Mini 3D Printer. We wish that all companies would follow that example and grant customers universal software freedom. Unfortunately, that is currently not realistic, even in the medium term.
Copyleft advocates have always contemplated that some companies will choose to ship proprietary software on the same device as the GPL'd works. Indeed, GPLv2 foresaw this possibility and permits that “mere aggregation” — as long as compliance is achieved for the GPLv2-covered works included on the device.
Indeed, GPLv2 was drafted as a forward looking license. Great care and attention was given to what the future might bring in software, and assure that in the future, GPLv2 defended software freedom adequately. In 1991, the year of GPLv2's drafting, one did not need to look that far ahead to see that general-purpose computers would find their way into devices other than servers, desktops and laptops. It was common, for example, in 1991 to have printers with full computers inside to handle various functionality of those printers. Famously, even back then, software freedom activists were quite frustrated that printer companies and their licensees would not liberate the proprietary software on these printers. Such activists, aware of this problem, sought to fix bugs in this printer software. They demanded source code for their printers, not because they sought to build their own printer from scratch and use that software, but because they wished to modify that source, fix the bugs, and reinstall the liberated printer firmware. This problem was well understood at the time of GPLv2's drafting, and GPLv2 was clearly drafted with this issue and use-case in mind.
To that end, GPLv2 included a clear obligation to provide “the scripts used to control … installation” that function for the GPLv2'd works. GPLv2 assures, to the purchaser of an embedded product, their absolute right to receive the information necessary to install a modified version of the GPLv2'd works. Meanwhile, rules for the legitimately proprietary works remain the prerogative of the licensors of that software. Since we have often been asked, we want to communicate this point with complete clarity and transparency: we would never require that any of the proprietary software on the device continue to function (or even be present) on the device after installation of a modified version of the GPLv2'd works on any device. However, installation of the GPL'd works must succeed and operate in a useful and functional fashion on the device.
Installation is where the proverbial rubber meets the road with software freedom. Of course, we honor the esoteric value of the freedom to study, and that right is important. But much more important, and a key reason that the GPLv2 was created, is the software freedom to reinstall a modified version. That means the right to fix bugs, the right to try out your improvements, and the right to remove privacy-disrespecting anti-features. It's the right that our community needs the most. The GPLv2 was designed to assure bug-fixing. Furthermore, the drafters knew that, on embedded systems and devices, you need to know how to install those fixes. Scripts can be technical artifacts like shell scripts, but can also be merely a recipe and/or guidance — written instructions that explain how to succeed at install.
We know that other software freedom organizations share this view. Conservancy is spearheading the ongoing effort to make this clarity widely known. Below is a simple statement of this position, phrased in other words:
The GPLv2 does not have any specific requirement for preservation of the ability to reinstall proprietary-software-centric vendor-provided firmwares (even if such firmwares contain some GPLv2'd works) on embedded systems, provided that the downstream user (i.e., the consumer with the device) can build, install, run, and (repeatedly and successfully) reinstall a firmware containing at least the copylefted components (such as Linux+Bash).
Not only is this consistent with what the license text says and requires, but it is also consistent with GPL's general policy goal. In our GPL compliance discussions, violators sometimes argue that, in order to install a modified version of the software received on a device, the user should build a new device themselves from scratch (instead of installing those GPLv2'd works on the device they have already). We don't believe that the original intent of the GPLv2 requirements for “the scripts used to control … installation of the executable” included that expectation, nor is that position supported by the license text. GPLv2 was written in a time after embedded devices already existed, and the intent is clear.
Our position is by no means controversial, but we do expect some will seek to argue it is controversial. We encourage you to consider their motives, funding sources, and licensing models. For our part, we published this policy statement to clarify repeated questions that companies distributing devices with GPLv2 software have recently raised in our GPL enforcement actions for Linux, BusyBox, and other software. We look forward to continuing the (sadly) long road toward compliance with these companies, in accordance with The Principles of Community-Oriented GPL Enforcement. We greatly appreciate the work that both individual contributors and companies put into their software and communities. It is our obligation, as copyleft activists, to ensure that GPLv2's rules apply fairly to everyone.
Finally, we encourage others to link to this statement when discussing GPLv2's “the scripts used to control … installation of the executable”.
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