A court case that open-source advocates say could have major repercussions on the GPL opened in German district court in Berlin Tuesday.
German DSL router vendor AVM has taken Cybits, which produces children's Web-filtering software, to court for copyright infringement for selling software that removes AVM's altered modules on the Linux kernel in their routers. The move is an attempt to stop Cybits from changing any part of the firmware used in the routers, including a key piece of free software.
The case could have huge consequences for free software, as both companies use the Linux kernel, which is licensed under the General Public License (GPL).
The kernel is the middle piece between applications and hardware resources that applications need to access. In order for the Cybits filtering program to work, it needs to alter certain parts of this kernel, removing some alterations to it made by AVM. But AVM claims that changing the kernel infringes on AVM's copyright.
Open-source advocates warn that the case represents a real threat to the GPL itself. This license allows everyone to use, study, share and improve works that use it, but it also imposes those same conditions on any company using GPL software. As such, AVM should not be able to prevent anyone from altering the Linux kernel, even on their own routers, according to the gpl-violations.org project, chartered to monitor use of the GPL.
"Ironically, by preventing others from enacting the rights granted by the GNU GPL, AVM itself is in violation of the license terms. Therefore they have no right to distribute the software," said Till Jaeger, co-founder of the Institute for Legal Aspects of Free & Open Source Software.
"I decided to contribute my work to the Linux kernel under the GPL and let others benefit from it. I'm happy if companies make a lot of money with software written by me and thousands of others," said Harald Welte, founder of gpl-violations.org and copyright holder of several parts of the Linux kernel. "But in return, when they distribute our software I want them to give others the same rights they received from me."
"If AVM are successful in court it will be disastrous for the global market for embedded devices, which includes mobile phones, network hardware and other Linux-based products," said Matthias Kirschner of the Free Software Foundation Europe.
According to the free software advocates, if successful, AVM could set a precedent for device manufacturers with the chance to veto software from third parties on their products, giving them an advantage over their competitors who are in compliance with the free software licenses that they use.
Calls to AVM's press office were not answered.
The court has not given an indication of when it will rule and whether it will call for further hearings.