Microsoft violated the GPLv2 licence when it released code for the Linux kernel this week, it has been claimed.
The infraction was made before Microsoft made the code available, according to an open-source network engineer.
Stephen Hemminger, principal engineer with open-source network vendor Vyatta, in a blog post claims that a network driver in Microsoft's Hyper-V virtualisation software used open-source components licensed under the GPL.
Since the licence does not allow for mixing of closed-source or proprietary code with open-source code, the software was in violation of the GPL, he said in the post, which details how the violation was discovered.
"This saga started when one of the users on the Vyatta forum inquired about supporting [the] Hyper-V network driver in the Vyatta kernel," Hemminger wrote.
"A little googling found the necessary drivers, but on closer examination there was a problem. The driver had both open-source components which were under GPL, and statically linked to several binary parts. The GPL does not permit mixing of closed and open source parts, so this was an obvious violation of the licence."
Hemminger said rather than "creating noise", he alerted Novell to the violation, which then informed Microsoft of the matter. He also congratulated Microsoft for releasing the code, which consists of four drivers that are part of a technology called Linux Device Driver for Virtualization.
"It took longer than expected, but finally Microsoft decided to do the right thing and release the drivers," he wrote.
Microsoft said through its public relations firm that it is working on a response to Hemminger's claims. Novell did not immediately respond to a request for comment.
Microsoft's announcement on Monday that it was releasing 20,000 lines of code under the GPL - a licence it has criticised and never used before - came as a shock to the industry, and Microsoft used it as yet another example of its interest in working with the open-source community despite a past of thorny dealings with that community. The Linux kernel is licensed under the GPL.
The drivers Microsoft released, once added to the Linux kernel, will provide the hooks for any distribution of Linux to run on Windows Server 2008 and its Hyper-V hypervisor technology. Microsoft will provide ongoing maintenance of the code under the GPL, the company said Monday.
Many see open-source software as the biggest threat to Microsoft's software business. The company has made broad claims that Linux violates many of its patents, and it continues to seek royalties from open-source companies that use Linux-based software.