Some members of the open-source community are claiming that the SCO Group may have violated the terms of the GNU GPL (General Public License) by incorporating source code from the Linux kernel into the Linux Kernel Personality feature found in SCO Unix without giving the changes back to the community or displaying copyright notices attributing the code to Linux.
A source close to SCO, who spoke on condition of anonymity, told eWEEK that parts of the Linux kernel code were copied into the Unix System V source tree by former or current SCO employees.
That could violate the conditions of the GNU GPL, which states that any amendments to open-source code used in a commercial product must be given back to the community and a copyright notice must be displayed attributable to Linux, he said.
The source, who has seen both the Unix System V source code and the Linux source code and who assisted with a SCO project to bring the two kernels closer together, said that SCO “basically re-implemented the Linux kernel with functions available in the Unix kernel to build what is now known as the Linux Kernel Personality (LKP) in SCO Unix.”
The LKP is a feature that allows users to run standard Linux applications along with standard Unix applications on a single system using the UnixWare kernel.
“During that project we often came across sections of code that looked very similar, in fact we wondered why even variable names were identical. It looked very much like both codes had the same origin, but that was good as the implementation of 95 percent of all Linux system calls on the Unix kernel turned out to be literally one-liners,” the source said.
Only a handful of system calls—socketcall, ipc and clone—were fairly difficult to implement as they involved the obvious differentiators between Linux and Unix: networking, inter-process communication and kernel threads, the source said.
“These system call implementations had to be quite compatible with the behavior of the real Linux kernel, otherwise Linux applications would not work on SCO Unix. It is quite obvious to argue that in order to get these right, Linux kernel code had to be studied and possibly copied into the SCO Unix kernel to implement the Linux Kernel Personality.
“How else would you get the Java Hotspot VM or the X-window server (Linux binaries) to work on SCO Unix?” the source questioned.
But Blake Stowell, a spokesman for SCO, told eWEEK on Tuesday that while the LKP used some open-source components, this did not constitute open sourcing that product. “That is a false notion. SCO also never used any of the Linux kernel code in the LKP and thus has not violated the GPL. We have also never contributed Unix source code to the Linux kernel,” he said.
Stowell also confirmed that SCO this week began shipping its UnixWare 7.1.2 and UnixWare 7.1.3 media kits after recently suspending these as they contained a Caldera OpenLinux 3.1.1 CD that provided LKP capabilities.
The move follows SCOs earlier decision to suspend shipments of its SCO Linux 4.0 and Caldera Open Linux 3.1.1 products due to intellectual property (IP) issues associated with the Linux operating system.
SCO last month sent its partners a letter designed to update them on the actions it was going to take with respect to LKP to address those IP issues.
“It is important to assure all users of UnixWare with LKP that they will be held harmless with respect to the SCO IP issue and may continue using the materials they have already received as we have announced for customers who have licensed any of SCOs Linux based products,” John Maciaszek, SCOs UnixWare Product Manager, said in the letter.
SCO has also examined the Linux RPM CD that shipped with the UnixWare Media Kits to expunge any material that was thought to have any IP issues, he said.
Maciaszek also contended in the letter that the LKP “does not need or use any of the Linux kernel to support the execution of Linux applications, consequently we do not expect this rework to have any impact on the utility of LKP for our customers.”
But members of the open-source community disagree and say SCOs legal claims that Linux is an unauthorized derivative of Unix and contains its proprietary intellectual property could be significantly weakened if it is shown that SCO incorporated parts of the Linux kernel into its Unix source code without giving these back to the community and since no copyright notices have been displayed attributable to Linux.
It is also no secret that Caldera International, which acquired the Santa Cruz Operation (SCO)—a UnixWare business and professional-services organization—in August 2000, wants to unify Linux and Unix on one platform.
In an eWEEK report based on comments made by Calderas then CEO Ransom Love in February 2001, Love said Caldera would make UnixWare binary-compatible with Linux, allowing UnixWare customers to run Linux applications.
On the flip side, Caldera Linux would gain UnixWares best enterprise and database management features. These included large file system support, asynchronous input/output (I/O), the UnixWare API, extended developer kit and multipath I/0, he said at that time.
Freelance reporter Jason Perlow contributed to this article.