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Institut für Rechtsfragen der Freien und Open Source Software

Hellwig vs VMware – GPL Enforcement Lawsuit in Hamburg District Court

by Florian Idelberger


The Software Freedom Conservancy recently announced that they are supporting a lawsuit against virtualization company VMware in a case of supposed GPL violation. Christoph Hellwig, a developer and thereby copyright holder in the Linux Kernel filed suit in the district court of Hamburg  March. The suit covers VMware’s alleged failure to comply with the terms of the GPL v2 when incorporating the Linux Kernel or other products in its ESXi line of products. Allegations of misuse have been made since 2007 and the investigation dragged on, with attempts for an alternative resolution not getting anywhere. Last year, the Software Freedom Conservancy was apparently informed by VMware’s legal counsel that they did not intend to comply and they actually thought they were in compliance.

This led Hellwig to launch a court action that is supported by the  Software Freedom Conservancy. The case seems to have broad support in the community, such as from the FSF, FSFE, OSI,  some members of the Linux Foundation and many Linux Kernel developers and other FOSS projects.

While court documents are not public by default, based on the press announcement LINK and the FAQ published by the software freedom conservancy so far, the main issue brought in front of the court seems to be related to the combination of the VMware “vmkernel” with Linux Kernel code licensed under the GPL v2 and accompanying kernel modules and drivers for which at least some source code was provided. 

The investigation as described by the Conservancy suggests that the vmkernel component makes calls to the Linux kernel code in such a way that happens when C code is compiled into a single program. While there are program interfaces available, these are not fixed and kernel code had to be modified to support “vmkernel”. Although at first, also when looking at the diagram of the kernel structure and the Linux Kernel running with vmkernel it might seem like this might a case of a “shim layer” that is supposed to create artificial distance between proprietary and open source code, the Conservancy holds that not only does this term have no meaning and changing the structure does not influence the legal situation, but that its investigation shows that Linux Kernel code was used and modified much more directly. To this end, the FAQ of the Conservancy on the matter gives an example of a file for the PCI subsystem that was modified in the Linux Kernel code to connect tightly to VMware’s vmkernel. If this finding is upheld in court, it would mean that VMware is in breach of the GPL and has to cease its use or comply with the GPL properly (which would mean fully open-sourcing VMware’s kernel), in addition to potential fines.

In any case, this seems to be (as to our and the Conservancy’s knowledge) the first case that really focuses on the question of what is a derivative work under the terms of the GPL v2, especially as this case will be adjudicated under German and EU law. The case is definitely of major importance for the IT industry, as the case could clarify or redefine what is allowed with code licensed under the GPL v2 and there are no precedents so far. Currently, it is uncertain when there will be news again and where it will lead, but we will try to keep you updated.


Disclaimer: The counsel in this case, Till Jaeger, is a founding member of ifrOSS.