About four months ago, Linux kernel developer and Novell fellow Greg Kroah-Hartman suggested to Microsoft that it release three drivers to be part of Linux under the GNU General Public License (GPL) terms that govern its code.
Kroah-Hartman, who helps oversee the inclusion of drivers into Linux, said he worked within his company to find the right contacts at Microsoft.
"They reacted well," Kroah-Hartman said on Tuesday. "They were open to it. It just took a while to hash out all the details."
Sam Ramji, Microsoft's platform strategy director, credited Kroah-Hartman for helping guide the company through the process. "He provided valuable guidance and feedback to the Open Source Technology Center (OSTC), which enabled the team to contribute the code in a way that was acceptable with the Linux kernel community processes," Ramji said in an email interview.
The move illustrates the combination of social, legal and technical factors that must be addressed before Microsoft's code could arrive. Anyone may contribute software to the Linux kernel, but getting it accepted can be a complicated matter, even for a company that has not bad-mouthed the GPL. This time, at least, Microsoft's pragmatism carried the day.
Microsoft had been working on the code contribution for some months, Ramji said. Its announcement this week coincides with the OSCON 2009 open-source conference, which is being held in San Jose, California.
Microsoft made the move largely to help strengthen Windows Server as a host environment for Linux.
"Microsoft decided to release the drivers to support broader adoption and facilitate better performance of Linux running as a guest operating system where Windows Server 2008 is the host," Ramji said.
Kroah-Hartman said Microsoft met all the requirements for inclusion of the code in the Linux kernel, adding that it will probably show up in version 2.6.32, which will be released in about four or five months.
Microsoft said it made sense to release the code under version 2 of the GPL, even though it has been critical of the GPL and has used other open-source licences for most of the code it has made freely available in the past.
"Because GPLv2 is the licence of the Linux kernel, we are releasing the device driver code under the GPLv2 licence to facilitate interoperability," Ramji said. "Our use of the GPLv2 licence, as requested by the Linux community, means we will not charge a royalty for, or assert any patents covering, the driver code we are contributing."
Kroah-Hartman, who heads the Linux Driver Project, has been arguing for some time that all Linux drivers should be released under open-source licences. He said Microsoft's move represents a change in its attitude toward the GPL and highlights that the GPL is a valid licence for a project to be released under.
"It's just a validation of what all of us have been publicly saying for many years," Kroah-Hartman said.
He noted that Microsoft is now a full-fledged Linux developer and will be responsible for maintaining its piece of Linux. He added that the community has already submitted a couple of patches aimed at improving Microsoft's code.
Microsoft has not closed the door to contributing more to Linux.
"We expect to maintain the Hyper-V Linux device drivers as part of our product development and support process for Hyper-V, which we expect will involve ongoing contributions," Ramji said. "Part of the OSTC's charter is to continually evaluate open source, market conditions, customer requests and scenarios, and as such, we will evaluate possibilities to work with additional open-source projects in the future, including the Linux Kernel.
"Microsoft is pragmatically focused on helping customers and partners be successful in a heterogeneous technology world. We both compete and partner with traditional commercial vendors, and will continue to do so with open-source-based businesses, with a focus on providing value for shared customers."
