GPL compliance suit against VMware dismissed

In a setback to the Christoph Hellwig's efforts to enforce the GPL on code that he wrote in the Linux kernel, his suit against VMware in Germany has been dismissed on procedural grounds. The court ruled that he had not provided enough specificity about the code he was claiming had been used by the company. The merits of the GPL and whether the two main parts of VMware's product constitute a derived work of the kernel were not even considered. There may be another chance for the court to do so, however, as Hellwig will appeal the dismissal.

The suit was announced by the Software Freedom Conservancy (SFC) back in March. SFC is funding the litigation, which revolves around VMware's ESXi virtualization product. ESXi has two pieces of interest here: the proprietary "vmkernel" that uses Linux code and drivers in an open source "vmklinux" module.

The source code for vmklinux unquestionably contains Hellwig's code and copyright notices. But vmklinux itself does comply with the GPLv2. The question then becomes: does combining vmklinux and vmkernel make the resulting executable a derivative work of the kernel? Hellwig argued that it does, but the court never even got to that point.

The court dismissed the suit on the grounds that "the materials submitted did not satisfy German evidence rules", Hellwig said on his blog. He provided links to the official ruling [PDF in German] and an unofficial English translation [PDF]. In that post, he announced his intention to appeal, and expressed his dismay that the main question of the case was never addressed:

The court chose not bring in an expert and relied on the filings made by Hellwig and VMware (which are not public, though they are referred to in the ruling). In Germany, the court decides whether expert testimony is required. Based on Hellwig's statement, it would seem that he and his legal team expected the court to do so in this case.

The judgment is split into two main parts: the "findings of fact", which is largely a restatement of the arguments both sides made in their filings, and the "reasons for the decision" that describes the problems the court found with Hellwig's evidence. The court decided that the suit was "admissible" even though Hellwig only held copyright on some portions of the kernel because he claimed "adapters copyright" on the changes that he made to parts of the kernel. The concept of "adapter's copyright" (or at least the term) appears to be specific to Germany, but the ruling makes it reasonably clear what is meant:

But, the fact that it is an admissible action does not mean that Hellwig is entitled to the injunction he seeks, unless his "pleading is sufficiently substantiated to establish the cause of action and whether the Plaintiff has proved where necessary [...] which parts of the Linux program he claims to have modified, and in what manner" That is the first of three tests (the others are establishing that his contributions meet the criteria for adapter's copyright and that VMware has in fact used that code) that are required to be met before the substantive questions about vmkernel and vmklinux can even be considered:

The evidence presented by Hellwig would seem to be files and other information that would be instantly recognizable by a kernel developer or many other members of the free-software community: Git repositories, tar files, git blame output, and so on. None of that information constitutes "an admissible pleading in court procedure", however. The problem seems to be that Hellwig did not directly and specifically show exactly which chunks of code in Linux were his and to link them to the corresponding chunks in vmklinux.

There were apparently three different facets of Hellwig's work on Linux that were part of the claims: his modifications to code throughout the kernel, his work on the SCSI subsystem starting in 2000, and his development of the radix tree code. For the changes to the overall kernel, the evidence presented was the publicly available Git repository of the kernel, which the court considered to be too broad. In addition, a CD containing the entire source code of Linux was submitted but it also lacked specifics:

There was also some git blame output submitted, which might serve to identify those with an adapter's copyright in the files, the court said, but it did not indicate where that code appeared in vmklinux, so it doesn't establish that the code was used by VMware. While there were statements that a full comparison had been made between vmklinux and the kernel, only some examples from that comparison were submitted. Furthermore, the two header files distributed with vmklinux that contain Hellwig's copyrights are not sufficient to show that he has an adapter's copyright in that code: "This cannot simply be assumed merely because the Defendant itself has named the Plaintiff as a possible modifier of Linux; instead, it must be established by the Plaintiff."

For the SCSI subsystem, Hellwig's filings are more specific, but still insufficient for the court. While he claimed to be one of the most active SCSI developers from 2000 to 2004, which involved "complex programming that merits protection", that claim does not provide enough information; "he needs to specifically name those programming achievements for which he seeks protection". The ruling also mentions that VMware had argued that only eight functions from the SCSI code submitted could be attributed to Hellwig's work and that Hellwig did not contest that argument. Furthermore:

The 19 patches to the SCSI hotplug functionality that were submitted were not tied to vmklinux, but also were not accompanied by a statement about how those contributions are complex enough for copyright protection:

For the radix tree work, the explanations offered in the filings evidently were not sufficient to convince the court that it should be covered by copyright. Radix trees are a data structure that are used in various places in the kernel, but the distinction between the code to implement them and the abstraction of the data structure was either not explicitly made or, perhaps, not understood by the court.

It seems clear that Hellwig's legal team did not anticipate the level of detail the court would require to establish the copyrights and where they were alleging that VMware was infringing them. The team also seems to have relied on the kind of evidence that would be compelling to a technical audience, but evidently was not precise enough for the court. For its part, VMware seems to have vigorously defended itself—if no code of Hellwig's can be shown to have been used by the company, clearly the whole argument disappears, thus the dismissal.

SFC also announced the appeal; in it, executive director Karen Sandler lamented that there is something of a mismatch in the resources each side has available to it:

The money expended by VMware could become a real issue if the appeal is not successful, as the court awarded VMware its costs when dismissing the case. That number is sure to be quite large at this point and will only grow through the appeals process.

The SFC also released a comparison of vmklinux and Hellwig's contributions to the kernel that was done by Bradley M. Kuhn. It shows considerable similarity between Hellwig's contributions and vmklinux. But, perhaps like what was filed with the court, it is a technical analysis, rather than a detailed, line-by-line annotation that the court seems to indicate that it wants.

Hopefully, the appeal is successful in at least getting past the procedural hurdles so that the court can rule on the more interesting (at least to the free-software community) part of the puzzle: whether vmklinux and vmkernel constitute a combined work that is derived from the kernel. Though it won't really set precedents either inside or outside of Germany, a ruling on that question would start to clarify some of the scope of the GPL, which will be helpful to both the community and those who might want to better understand all of the facets of where and how the license applies.