Proprietary Linux extensions reportedly violate the GPL
Linux developer Andy Grover has posted to the kernel developer mailing list (LKML) to accuse RisingTide Systems of violating Linux kernel licensing conditions with its RTS OS storage operating system. This has led to a discussion in which prominent kernel developers, a RisingTide employee and a legal representative for the company have explained their positions. Discussion has also turned to NVIDIA's proprietary Linux drivers and related cease and desist notices.
Andy Grover, who in the past maintained the Linux kernel's ACPI support infrastructure and now works on SCSI target support for Red Hat, claims that the SCSI target implementation in RTS OS provides functions which are not present in the LIO (linux-iscsi.org) target implementation included with current kernel versions. Like the target in RTS OS, LIO was developed by RisingTide Systems. The company sent the kernel-side code for LIO to Linux developers who merged it into Linux 2.6.38, since which time the company has maintained and significantly extended the code in the Linux kernel. The company uses an enhanced version in its RTS OS, however, and keeps some of the code responsible for the additional functionality under wraps.
In the course of discussions on the mailing list, Grover and some other kernel developers have expressed some doubt as to the legality of this approach. They argue that the code relies on other functions provided by the Linux kernel and has been written specifically for it. It is therefore, they believe, a derivative work to which the conditions of the GPL 2.0, under which the Linux kernel is licensed, apply. If the application in question were standalone, RisingTide's approach would probably not be a problem, since as long as one company has sole copyright to code licensed under the GPL 2.0, it can also distribute the source code and software based on it under other licenses. According to Nicholas A. Bellinger, who maintains the LIO target in the kernel and co-founded RisingTide Systems, the company does indeed hold sole copyright.
An email from Lawrence Rosen, a lawyer who states that he has been advising RisingTide on the issue in question, states that the target code in Linux cannot be classified as a derivative work solely on the basis that it uses the Linux API. He says that this has been demonstrated by cases such as the recent ruling in Oracle's lawsuit against Google on Java copyrights and patents. Dave Airlie, who maintains the Linux kernel's main graphics driver subsystem, claims, however, in another email that the GPL does apply if RisingTide Systems distribute the enhanced target implementation in combination with the kernel. This seems to be the case in RTS OS. In this and a further email, Airlie compares the situation with NVIDIA's proprietary Linux graphics drivers. Airlie notes that it is hard to argue that the latter are a derivative work, as they contain a lot of driver code developed for Windows. But he then points out that NVIDIA does not distribute its drivers in combination with a Linux kernel and distributions which have attempted to do so have been served with cease and desist notices.
Besides Dave Airlie and Andy Grover, other prominent kernel developers were also involved in the discussion, including Theodore Ts'o and Alan Cox. Some of them are careful to stress in their mails that they are not lawyers. Time will tell whether Linux developers will now get actual lawyers involved to clarify the issue. A solution or decision could be reached behind closed doors or in front of a court, but it is almost certain that it will not be reached on the public kernel developer mailing list.
- NVIDIA wants to remove GPL marker from Linux interface, a report from The H.