RealTime IT News

Windows 7 Virtualization Leaves Some CPUs Out

The revelation last Friday that Windows 7 would come with a virtual mode to run Windows XP has been qualified with the realization not every processor will support it.

A number of bloggers, beginning with ZDNet's Ed Bott, have noted that to run Windows XP Mode in Windows 7, your processor has to have hardware virtualization technology. Fortunately, both Intel (NASDAQ: INTC) and AMD (NYSE: AMD) have been flogging that very feature in their chips, even if no one used them before.

Intel offers Intel-VT while AMD offers AMD-V. Both companies have made these features selling points in new product introductions for some time.

As it turns out, Windows XP Mode might be the first high-profile product to put the feature to use, at least on the client side, notes Nathan Brookwood, research fellow with Insight 64. "With a lot of these kind of features, they never get used but provide the assurance to get prospective users over the hump to make a purchase," he told InternetNews.com.

Support for these technologies is not across the board, however. Intel-VT can be found in some very old Pentium 4 models – the 662 and 672 – but not in certain Core 2 processors. There are even some Atom chips with –VT, but not all Pentium-D processors. The Core 2 family is quite varied, according to this Intel product list.

In the case of AMD, it introduced AMD-V in 2006 with the Athlon 64 and Athlon 64 X2 with family "F" or "G" on socket AM2. Earlier generations of AMD chips that used the Socket 939 do not include AMD-V. The "Sempron" family also does not support AMD-V.

Why worry?

However, there doesn't seem to be a lot of worry about this inconsistent support.

Intel notes that the Windows XP Mode will be in the high-end versions of Windows 7. The XP mode will only come in Windows 7 Professional, Enterprise, and Ultimate editions. "Typically, the high-end OS will be paired with a high-end processor, which will have –VT," said an Intel spokesperson. AMD did not return calls for a comment by press time.

Brookwood thinks most Windows 7 sales will be with new machines, so the point is moot. "You have to realize that hardly anybody upgrades an existing platform to a new OS," said Brookwood. "You run into all sorts of problems if the machine is more than a few years old. It gets ugly quickly. So although Microsoft will encourage everybody to upgrade, but in practice, hardly anybody upgrades."

The real issue, he added, is that this will help people get past horror stories of application incompatibility. "That might be a good reason not to buy a new box with Windows 7," said Brookwood. But now the backwards-compatibility mode "very nicely handles an objection to a new sale, so I think this makes wonderful sense," he added.