Windows 8 with Hyper-V will require new hardware

Microsoft confirms client-side hypervisor, which requires 64-bit system with SLAT but can run both 32- and 64-bit guest OSes

Just as we reported back in June, the coming version of Windows 8 will include Microsoft's Hyper-V hypervisor, which will no longer be exclusive to Windows Server 2008 and Windows Server 2008 R2. On Wednesday, Microsoft finally acknowledged this fact with an official post on its Building Windows 8 blog.

This isn't Microsoft's first foray into client-side virtualization. Among other things, Microsoft's Windows Virtual PC was available with Windows 7, and it enabled XP Mode for backward compatibility.

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We've been anticipating this announcement since blogger Robert McLaws first discovered the Hyper-V capability in a leaked build of the Windows client OS. McLaws also noted enhancements to the hypervisor that would prove equally exciting to see in both the client and server worlds. Evidently there will be a number of new storage, memory, and networking enhancements, including a new virtual hard drive format (.vhdx) that allows for up to 16TB of data, as opposed to the 2TB limit of .vhd. And Microsoft will add support for four core CPUs, hardware acceleration, and a host of other items.

This latest post from Microsoft does not specify which of the Windows 8 client SKUs will actually include Hyper-V. It does, however, note that the licensing rules for the client version of Hyper-V will not differ from its Server sibling; you still need to license any operating systems you use as a guest within the VMs.

Hyper-V on Windows 8 will continue to require 64-bit processors with Intel's VT-x or AMD's AMD-V virtualization technology, but it adds new hardware requirements.

"Hyper-V requires a 64-bit system that has Second Level Address Translation (SLAT)," explains Hyper-V program manager Mathew John on the Microsoft Windows 8 blog. "SLAT is a feature present in the current generation of 64-bit processors by Intel & AMD. You'll also need a 64-bit version of Windows 8 and at least 4GB of RAM."

SLAT is an updated version of hardware virtualization that's included in more modern Intel and AMD processors, such as Intel's Core i3, i5, and i7 processor series and AMD's latest Barcelona processors. This type of hardware virtualization requirement isn't new to Hyper-V, but it is more restrictive than the current specifications found on Server. If this same SLAT requirement spills over into the next version of Windows Server, then some machines already running Hyper-V today may not be able to run the new hypervisor after upgrading.

Despite requiring 64-bit hardware and a 64-bit version of Windows 8, Hyper-V still provides the ability to run both 32- and 64-bit guest operating systems. Microsoft notes that up to four VMs can be hosted on a 64-bit system with 4GB of RAM, though more VMs will require a greater amount of memory.

Building Hyper-V into the Windows 8 client will give Microsoft a new way to support legacy Windows applications and maintain compatibility with the Server OS. Microsoft's John also writes that this new feature should prove valuable to IT professionals and developers who need access to multiple environments.

"Hyper-V enables developers to easily maintain multiple test environments and provides a simple mechanism to quickly switch between these environments without incurring additional hardware costs," writes John. "For example, we release preconfigured virtual machines containing old versions of Internet Explorer to support web developers. The IT administrator gets the additional benefit of virtual machine parity and a common management experience across Hyper-V in Windows Server and Windows Client. We also know that many of you use virtualization to try out new things without risking changes to the PC you are actively using."

That said, features or applications that depend on specific hardware still do not work well in a VM. Games or applications that require processing with GPUs may not work well. Some applications, such as Windows BitLocker and Measured Boot, might not function properly either. Even with the enhancements being made to Hyper-V and its movement to the client machine, all applications still do not necessarily play well within a VM.

Windows 8 will reportedly arrive sometime in 2012. You can bet that Microsoft will reveal more information and details about this release next week at the BUILD conference scheduled for Sept. 13-16 in Anaheim, Calif.

This article, "Windows 8 with Hyper-V will require new hardware," was originally published at Follow the latest developments in virtualization at For the latest business technology news, follow on Twitter.

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