Linux vendor Novell says Linux doesn't violate Microsoft patents, even though Novell recently signed an agreement with Microsoft protecting Novell SuSE users against patent lawsuits from Microsoft.

But Microsoft shot back that the two companies "agreed to disagree" on whether some open-source projects infringe on Microsoft patents. Both Microsoft and Novell are committed to their agreement to advance the interoperability of Windows and Linux, Microsoft said.

The two companies made a deal this month that included patent protections, support cooperation, and codevelopment of technology for Windows-Linux interoperability. As part of the agreement, Microsoft promised not to sue Novell for patent infringement stemming from code currently in Novell's SuSE Linux, or future technology codeveloped by the companies. At the same time, Microsoft got the same patent protections from Novell.

The implication that Microsoft code could be in Linux set off a frenzy within the open-source community, with developers demanding that Microsoft show the infringing code. Microsoft CEO Steve Ballmer fanned the flames further last week when he said, "Anybody who's got Linux in their data center today sort of has an undisclosed balance sheet liability." The remarks were made to the Professional Association for SQL Server in a discussion posted on the Seattle Post-Intelligencer's site.

Hovsepian distanced Novell from Microsoft and Ballmer, saying, "We disagree with the recent statements made by Microsoft on the topic of Linux and patents," in his letter.