Microsoft to Make Viridian Hypercall API Widely Available

The Windows Management Interface to the virtualization technology will also be accessible to partners.

Microsoft will make the hypercall API in Windows Server virtualization available under its Open Specification Promise when the product is released to manufacturing late next year.

This means that the API can be used without licensing fees and with Microsofts guarantee that it will not sue for violation of its patented intellectual property.

However, for customers who want early access to the interface, Microsoft has posted an updated draft of the hypercall API to its Web site.

The move will be announced Oct. 24 at the Interop New York 2007 conference and expo, where Microsoft is showcasing some of the interoperability resulting from its collaboration with the companies that are part of the Microsoft-sponsored Interoperability Vendor Alliance.

"The OSP [Open Specification Promise] is a simple, clear way to reassure a broad audience of developers and customers that any Microsoft patents needed to implement all or part of the specification can be used for free, easily, now and forever, to the extent that the specification is being implemented," Patrick ORourke, group product manager for Microsofts server and tools business, told eWEEK.


To read more about Microsofts move to make its Virtual Hard Disk image format specification available to users, click here.

The Windows Management Interface to Viridian—the code name for Windows Server virtualization—is based on the industry standard in development in the DMTF (Distributed Management Task Force), and will also be made accessible to partners, he said.

The hypercall API enables partners to develop solutions with Windows Server virtualization, which they can use to integrate or extend their software with Windows Server 2008 and Windows Server virtualization.

"For example, this is the API to which Novell and XenSource are developing against for interoperability with Viridian," ORourke said.

Microsoft, of Redmond, Wash., first distributed the hypercall API documentation to attendees of its 2006 Windows Hardware Engineering Conference. The company has gotten feedback on the hypercall APIs from, among others, the Xen and Linux communities through its relationships with XenSource and Novell, he said.


Read more here about why Microsoft cut core features from Viridian.

VMware and the major chip and OEM vendors have also had access to drafts of the hypercall API specification, ORourke said.

"This move follows on our earlier decisions to extend the OSP to virtualization and is another step in our efforts to promote technical development in the virtualization space in the broader community by contributing our own technology to the space," Tom Robertson, Microsofts general manager for interoperability and standards, told eWEEK.

When Microsoft and XenSource joined forces in July to facilitate server virtualization, Frank Artale, vice president of business development at XenSource, said a key piece of the work would be to provide an adapter between the Xen hypercall API and the Microsoft Viridian hypercall API.

XenSource CTO Simon Crosby said the company is committed to delivering value-added virtualization solutions for the Windows platform and that interoperability with Viridian was an important element.


Read more here about the alliance between Microsoft and XenSource.

"This is made possible by Microsofts licensing of key technologies such as its VHD image format and the Windows Server Virtualization hypercall API, which will allow us to ensure that Xen-enabled Linux guests will be compatible with Windows Server virtualization when it is delivered as a component of Windows Server 2008," he said.


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