Brian Gammage

Windows 7 is based on the same technology generation as Windows Vista – which despite talk of layers (more than 60) and components to decouple some components, was a very large, complex and highly integrated bubble of software. When presenting at conferences, I often compare the highly integrated nature of the Windows OS with badly cooked spaghetti – everything is stuck together. This isn’t pejorative, it’s just a reflection of where we are and audiences usually agree.

We are all victims of history, especially when it comes to key infrastructure components like Windows. In the mid 1990s, the main challenge in client computing was getting applications to work with diverse hardware. To overcome this, we built big OSs to integrate shared functions and connect the applications layer with the hardware one. Now our main challenge in client computing appears to be managing the big OSs we’ve created. Food for thought there as we plan future developments and deployments (not only of Windows, but also of all the infrastructure we use for the care and feeding of our client computing environments).

Windows 7 is necessarily more of the same, but also promises to be an important step in a better direction. It is much easier to virtualize, which means it will be an easier “bubble” to package and deliver. Virtualization decouples the OS from the layers above (applications) and below (hardware), making its configuration more tolerant of changes in their configurations. For previous versions of the Windows OS, the latter was challenging in that many functions were designed to be closely coupled to hardware. Some instructions expect to be handled directly, not by an intermediate layer of software (which might also want to share access with another OS). Windows Vista in particular presented issues when virtualized, making it a particularly bad candidate for hosted virtual desktop (HVD) deployments.

Although the changes will remain invisible to most users, Microsoft has clearly done work on the underside of Windows 7, where it meets hardware. To support XP Mode, they have extended support for hardware capabilities that enable and support a privileged hypervisor. Although Windows 7 has not moved down to occupy these new privilege levels and does not ship with a hypervisor, the extended support means that Windows 7 works with the VT instruction set extensions – in other words, the instructions that previously need to go direct to hardware can now be intercepted by an intermediate layer.

Will these changes make a big difference to you? Unlikely, unless you want to run Windows 7 in an HVD (where you will find its small footprint helps too). But they point to a much more modular future in which Windows is no longer tied to hardware and can be moved more freely from device to device. They also support our expectations for Windows 8.

So changes under the hood, but then OS architecture changes should be invisible. As we battle the complexity of the client OS, our objective should be to make the OS as unobtrusive as possible. Despite this, these changes are fundamental. Microsoft has cut some of the chains of complexity – it has started to unbundled the badly cooked spaghetti for enterprise users.