Virtualization Daily

Microsoft has announced the availabily of its virtual machine hard drive specification under the terms of their Open Specification Promise which says.

Microsoft irrevocably promises not to assert any Microsoft Necessary Claims against you for making, using, selling, offering for sale, importing or distributing any implementation to the extent it conforms to a Covered Specification (“Covered Implementation”), subject to the following. This is a personal promise directly from Microsoft to you, and you acknowledge as a condition of benefiting from it that no Microsoft rights are received from suppliers, distributors, or otherwise in connection with this promise. If you file, maintain or voluntarily participate in a patent infringement lawsuit against a Microsoft implementation of such Covered Specification, then this personal promise does not apply with respect to any Covered Implementation of the same Covered Specification made or used by you. To clarify, “Microsoft Necessary Claims” are those claims of Microsoft-owned or Microsoft-controlled patents that are necessary to implement only the required portions of the Covered Specification that are described in detail and not merely referenced in such Specification. “Covered Specifications” are listed below.

This promise is not an assurance either (i) that any of Microsoft’s issued patent claims covers a Covered Implementation or are enforceable or (ii) that a Covered Implementation would not infringe patents or other intellectual property rights of any third party. No other rights except those expressly stated in this promise shall be deemed granted, waived or received by implication, exhaustion, estoppel, or otherwise.

This supposedly allows open source developers to use the Microsoft published specifications within their applications.

The Virtual Hard Drive specification is supposedly available without registering, but the link doesn’t work. Maybe they’ll have fixed it by the time you read this. You can also download by registering, though I haven’t tried that. Earlier this year, VMWare also released an open specification for their hard drive format and given the popularity of VMWare it seems likely that it will be the more relevant going forward. The Microsoft format will is really only of value if you want to build tools that target the Windows specific virtualization tools that Microsoft is shipping.

Update: Billy Marshal also has some interesting things to say about this.