Microsoft, which has been at war with the Linux community over the years, has abruptly changed face and has released 20,000 lines of Linux code to the Linux kernel community.

Available for inclusion in the Linux tree, the code includes three Linux device drivers; it will be available to both the Linux community and customers. It will enhance the performance of the Linux operating system when virtualised on Microsoft Hyper-V Server 2008 virtualisation software, according to Microsoft. Code will be offered under the GNU General Public License 2.

"We are seeing Microsoft communities and open source communities grow together, which is ultimately of benefit to our customers," said Microsoft's Sam Ramji, senior director of platform strategy in the company's Server and Tools organisation. "The Linux community, for example, has built a platform used by many customers. So our strategy is to enhance interoperability between the Windows platform and many open source technologies, which includes Linux, to provide the choices our customers are asking for."

"Today's release would have been unheard of from Microsoft a few years ago but it's a prime example that customer demand is a powerful catalyst for change," said Ramji.

Indeed, Microsoft has been involved in ongoing disagreements with open source advocates, with Microsoft claiming open source projects like Linux violate 235 Microsoft patents.

Ramji also cited the current economic climate as a driving force. "Many companies are turning to Microsoft more frequently to help them succeed in a heterogeneous technology world because we understand that reducing complexity is a key factor to reducing cost. We are seeing interoperability as a lever for business growth," Ramji said.

In a statement, the executive director of the Linux Foundation saw Microsoft's effort as validation of open source.

"We see the move by Microsoft to submit its device driver code to the Linux kernel as a validation of the open source development model and the GPLv2 licence," said Executive Director Jim Zemlin. "Even if a bit overdue, we applaud Microsoft for recognizing the value of collaboration in order to compete in today's IT market."

An industry analyst concurred that the move was precedent-setting.

"This is a logical but precedent-setting decision for Microsoft. Credit Microsoft for recognising the reality that a sizable portion of its customer base was going to be running Linux and Microsoft side by side in virtualised environments, so it would be important to be competitive on an interoperability front," said Stephen O'Grady, analyst at Redmonk.

"For all of its logic, however, this is a move that would have been inconceivable a few years ago, meaning that the glasnost of Microsoft vis a vis open source continues," O'Grady said.

Continuing a recent mantra of accommodations for open source, Tony Hey, corporate vice president of the external research division at Microsoft Research, will address the O'Reilly OSCON (Open Source Convention) later this week about the company's commitment to open access, open tools and interoperability in the "heterogeneous world of research," . Hey will discuss tools for scientists to process and analyze massive amounts of data to accelerate scientific discovery.

Microsoft also is highlighting its ongoing investment in optimizing PHP on Windows Server and the Microsoft SQL Server database. The company has had work ongoing on a SQL Server driver available for PHP to support more native features in SQL Server 2008. Microsoft also has partnered with PHP tools vendor Zend Technologies to boost PHP.