VMware GPL case is back in court—will we finally get some clarity on the meaning of "derivative work"?

One of the most active Linux kernel developers, Christoph Hellwig, backed by the Software Freedom Conservancy, (unsurprisingly perhaps) has struck again against a virtualisation giant—VMware. for breaching the GNU General Public Licence (GPL). More than two years after the Hamburg District Court’s dismissal, an appeal has been filed in the German Court of Appeal. This case has attracted a worldwide attention because the claims raised call for court’s interpretation of the scope of the GPL applicability and, in particular, the reach of its copyleft effect.

Background

VMware describes the architecture of its ESXi product as—

“… an operating system that manages the hardware and software resources of the physical server. At the core of the ESXi operating system is a kernel called "vmkernel", that provides control over those resources. […] vmkernel has a general-purpose API called "VMK API" that enables device drivers and other loadable modules to perform specialised functions. Third parties can write drivers and modules that interact directly with the vmkernel utilising the VMK API. And while these drivers do not need to be Linux drivers, when they are, we offer a compatibility alternative through a loadable kernel module called "vmklinux", which in association with any Linux drivers, is loaded by the vmkernel and interfaces with the vmkernel through VMK API.”

VMware has licensed vmklinux under the GPL, but ESXi is only available under a commercial licence.

Hellwig alleges that VMware has combined his contributions to Linux kernel with its own code into a proprietary product in breach of GPL provisions. Sections 2 and 3 of the GPL require the user to distribute the derivative works under GPL and accompany any such distribution with “the complete corresponding machine-readable source code,” or a written offer thereof. However, if identifiable sections are not deemed to be derivative works, and can be reasonably considered independent and separate works, then GPL will not apply to those sections when they are distributed as separate works. The question at issue is whether GPL’s viral effect reaches the vmkernel when the drivers and vmklinux are licensed under GPL. 

SFC’s view of system architecture

VMware's defence primarily rests on two pillars. Firstly, VMware contends that Hellwig lacks standing on the basis of copyright to bring an action and, secondly, that vmklinux is not a derivative work of Linux kernel, but merely an “interoperability module”, i.e. a separate work, which communicates through a stable interface, VMK API. 

The Hamburg District Court in the first instance did not rule on the merits of the case, basing its decision to dismiss solely upon evidentiary deficiencies, namely, Hellwig’s failure to identify in VMware’s product the specific lines of code authored by him. 

This Kat needs clarity on the meaning of "derivative work"

As Hellwig promised, he has now sought recourse from the court of appeal. If the parties cannot reach a settlement by a set deadline, the German Court of Appeal is expected to adjudicate the appeal.

Is this The Test Case?

The notion of a derivative work in a GPL context has been a big unknown for nearly two decades. Such uncertainty and potential risk of having to open-source proprietary code has led many commercial entities and open source projects to refrain from including a GPL’ed software in their codebase. 

Hellwig v VMware might become a gamechanger, if it provides for the first time much-anticipated judicial clarity as to what implications software architecture has for licence interpretation and how copyright law fits in. That said, given the wide diversity of the structure of software is built and how it is distributed any decision in this case will not likely be the last word.

Image credits: Software Freedom Conservancy and PJZWOLF