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Be Prepared for Windows 8 Hyper-V Gotcha

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September 19, 2011

September 19, 2011

I stumbled into an interesting potential “gotcha” as regards Windows 8 and its much-ballyhooed support for Hyper-V (see Steven Sinofsky’s Building Windows 8 blog entitled “Bringing Hyper-V to ‘Windows 8′” for more information) while researching an article on this topic for SearchWindowsEnterpriseDesktop.com this weekend. Although Microsoft has claimed in the past that Windows 8 will run on any PC that can run Windows 7, the same is most definitely NOT TRUE for Hyper-V support.

To run Hyper-V, a PC must not only run the 64-bit version of Windows 8, its CPU must also support a virtualization technology called Second Level Address Translation (aka SLAT) which, as Sinofsky’s blog states, “…is present in the current generation of 64-bit processors by Intel and AMD,” along with at least 4GB of RAM. Given the memory requirements for VMs, the 4 GB requirement is neither terribly surprising nor onerous. As it turns out, only the ix Intel processors (i3, i5, and i7) and Barcelona-model or later AMD processors (K10 or higher Opteron and Phenom CPUs) support SLAT.

You can check the status of your CPUs by downloading the latest version of Mark Russinovich’s coreinfo.exe utility from the Microsoft Sysinternals Web pages, then launching the utility from a command line launched with administrative privileges. If your CPU will run Windows 8 Hyper-V, you’ll see a display like this one:

Coreinfo -v produces virtualization info

Coreinfo -v produces virtualization info

The key entries in this display are the EPT (Extended Page Tables) for Intel processors, as shown in the preceding screenshot, and a value in the AMD processor output that may appear as NPT (Nested Page Tables) or RVI (Rapid Virtualization Indexing). Simply put, one of these values must be enabled for Windows 8 Hyper-V to work. What this also means is that even though I have some older quad-core systems that run Windows 7 just fine, with 12-16 GB of memory (and thus plenty able to host multiple VMs except for the SLAT requirement), I won’t be able to use those machines to host Hyper-V VMs when I start digging into Windows 8 later this month. All I can say is “Rats!”

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About the author

Ed Tittel

Ed Tittel has spent over 30 years in the computing industry. He’s worked as a software developer and manager, a networking consultant, a trainer and course developer, and a technical evangelist. He’s worked for companies that include Burroughs, Schlumberger, Excelan, Novell, IBM/Tivoli and NetQOS (now part of CA). He also ran a content factory named LANWrights from 1994-2004, and produced 50-plus computer trade books yearly, on average. By 1994 Ed had worked on a dozen books and written over one hundred articles. That’s why he took the plunge when Novell closed its Austin, TX, offices to go out on his own. Over the next decade he would contribute to 100-plus books, start his own company, create the Exam Cram series of IT Certification books, and dig deeply into content development and delivery for various publishers and corporations. Ed has published with Academic Press, Addison-Wesley, Charles River Press, Course Technology, IDG Books, Pearson, Sybex, and Wiley. He has also written for the following corporations: Ciena, Cisco, Fortinet, HP, Microsoft, Novell, and Symantec, among others. Ed’s areas of technical interest include: markup languages; information security; Windows operating systems; and Web development tools and technologies. Ed currently blogs for IT Career JumpStart, Windows Enterprise Desktop, and Ed Tittel’s IT Certification Success. He also writes regularly for Websites that include InformIT.com, ReadWriteWeb.com, SearchWinIT.com, and others. Ed works occasionally as an expert witness on Web development technologies and markup languages, too. Follow Ed on Twitter (@EdTittel) or visit his blogs to learn more about current work and activity.

Permanent link to this article: http://www.edtittel.com/win7view/be-prepared-for-windows-8-hyper-v-gotcha.html

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  1. The Real Secret Behind SLAT and Hyper-V for Windows 8 - Windows Enterprise Desktop says:

    September 19, 2011 at 3:34 pm (UTC 0 )

    [...] upcoming release of Windows 8 (see my recent blog on this discovery at edtittel.com: “Be Prepared for Windows 8 Hyper-V Gotcha“) I’ve been wondering about why it has to be this way. So I dived into the [...]

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