Kaefer confirmed that the two companies shared their respective patent portfolios with each other before signing the deal, though he said that was also a typical business practice. "We said 'This is what we got.' Both companies were aware of what each other has," Kaefer said.

Neither he nor Dragoon would say how extensive the patent review was, nor whether it turned up any possible violations of Microsoft patents in the Linux source code.

Asked whether Microsoft would consider revealing what parts of Linux allegedly violated the company's intellectual property so that open-source developers could throw out the offending code, Kaefer demurred, saying it would not be "very productive."

"Patents are hard to understand. You have to have a certain level of expertise to understand the scope. And there are legitimate questions about patent quality," he said. "The reality is that you'd have to look at thousands of patents and thousands of products. To focus on every single one would be prohibitive."

Asked whether Linux hobbyists and desktop users should worry about Microsoft suing them, Kaefer said Microsoft "does not have a history of patent litigation," having sued only one company, peripherals manufacturer Belkin Corp., in the last decade.