Windows 8: Using Hyper-V on non SLAT CPUs?

[German edition] Windows 8 Pro and Enterprise are shipped with Hyper-V 3.0 in 64 Bit versions. But a CPU with SLAT support is mandatory (see my German article [2]). Otherwise, only the Client (Hyper-V-Manager) is useable, whilst the Hypervisor (Hyper-V-Platform) will be blocked. Recently there was a rumor [3, 4], that Hyper-V-Platform will be useable in Windows 8 on non SLAT CPUs. Well, I have tested it.


Some theory and a rumor

Hyper V 3.0 shipped with Windows 8 consists of Hyper-V-Manager and Hyper-V-Platform. Hyper-V-Manager will run as a front end also on 32 bit environment and doesn't require SLAT support. The Hypervisor, called Hyper-V-Platform, is restricted to 64 Bit Windows 8 versions and requires a CPU supporting virtualization support (Intel VT-X, AMD-V) and also Second Level Address Support (SLAT) – see also my Article [1].

In [3, 4] some people mentioned, that only the GUI of Windows Features will check a CPU's Hyper-V support. If that isn't available, activation of Hyper-V-Platform will be blocked (grayed out). But there should be a way, to add this feature using DISM – and afterward Hyper-V-Platform should be useable…

Test it! Here we go – Part 1

After André from left a comment about this topic, I decided to try a proof of concept. I was eager, to see, how Hyper-V will work, because I haven't a computer with a SLAT supported CPU anymore. A Dell Inspiron One 2330 with Intel iCore i7-CPU, I've had for test purposes, was send back to Dell a while ago. Currently I'm using a system with Intel Q8300 Quad Core CPU, that supports Intel VT-X.

Because this machine runs with Windows 7, I created a 64 Bit Windows To Go from Windows 8 Release Preview [1]. Then I booted Windows To Go, went to Windows 8 Desktop and entered the administrative command prompt (via hover "Start" button). Then I activated all Hyper-V features using the following command:

DISM /online /Enable-Feature:Microsoft-Hyper-V-All

DISM confirmed the successful execution of that command and asked for a reboot. The system started to reconfigure and booted twice. But during 2nd boot, the screen went black. Then I booted the system again, but this time with a distinct Windows 8 installation, went to an administrative command prompt and used the following command to deactivate Hyper-V.

DISM /Image:R:\ /Disable-Feature /FeatureName:Microsoft-Hyper-V-All

After reboot, Windows 8 worked again. I tried that twice, always ending with a black screen. Once I tried to boot with F8 in secure mode. I was able to see the secure desktop and in Windows features I could see, that Hyper-V-Platform was activated. And I was able to invoke Hyper-V-Manager and configure a VM with a preinstalled Windows Server 2008. But I wasn't able to run this VM – I got a notification, that this wasn't supported in secure mode.


A 2nd test with a native Windows 8 RP (64 Bit) install

Then I installed Windows 8 RP (32-Bit-Pro-Version) on that machine. As estimated, I wasn't able to activate Hyper-V-Platform in Activate or deactivate Windows features (see sceenshot of my German dialog box), because the option was grayed out.

Gesperrter Hyper-V-Plattform-Eintrag

Then I invoked an administrative command prompt from Windows desktop and entered DISM-command shown below:


The command was successfully processed and the system rebooted. After two boots, Windows 8 was able to launch and I controlled feature settings (which was set as shown below).

Windows-Features mit Hyper-V

Then I invoked Hyper-V-Manager via Start screen – and suddenly I was able, to configure a virtual machine.


And after clicking the connect button, I could see the following window.


But I wasn't able to run the VM using the run button because of an error dialog, informing me, that the CPU doesn't support virtualization (Intel Q8300 supports VT-X, but no SLAT).

Fehler beim Hyper-V-Start

I tried to inspect Hyper-V services. But all Hyper-V services stalled (obviously due to lack of SLAT support).

Will the right BCD entry helps?

André from suggested to enter the following command in administrative command prompt (see also).

bcdedit /set {current} hypervisorlaunchtype auto

After rebooting my system I tried Hyper-V-Manager again. My attempt, to invoke a VM vie Hyper-V platform resulted in the same error message. I came to the conclusion, that the rumor in the net about running Hyper-V on non SLAT CPUs was never tested with Windows 8 Release Preview.

But there is a positive result at least!

After adding a Hyper-V role to my Windows 8 client, I wasn't able to run the hypervisor. But I was at least I was able to configure VMs in Hyper-V-Manager (because a Hyper-V-Server was already detected and shown). Maybe I will use Windows Server 2008 R2 or 2012 (which didn't require SLAT support for Hyper-V) to run a VM – and use a Windows 8 client to connect to this server.

1: Windows To Go with Windows 8 Release Preview
2: Windows 8: Hyper-V braucht SLAT fähige CPUs
3: Technet-Diskussion: Hyper-V ohne SLAT
4: Artikel zu Hyper-V auf Windows Server 2012
5: Hyper-V vorübergehend abschalten
6: Technet-Article about Hyper-V

Similar Artikle (German):
i: Windows 8: Hyper-V im Test – Teil I (Hyper-V einrichten)
ii: Windows 8: Hyper-V im Test – Teil II (Host vorbereiten)
iii: Windows 8: Hyper-V im Test – Teil III (VMs aufsetzen)
iv: Windows 8: Hyper-V im Test – Teil IV (VMs einsetzen)

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3 Antworten zu Windows 8: Using Hyper-V on non SLAT CPUs?

  1. Günter Born sagt:

    Nachtrag: Gerade bin ich auf einen Beitrag [1] zu Windows Server 8 und Hyper-V gestoßen, der vielleicht von Interesse ist.


  2. Pingback: The things that are better left unspoken | Five Must-Have Hardware components to get the most out of Windows 8 (and Windows Server 2012)

  3. Pingback: The things that are better left unspoken | Is your organization ready for Windows 8.1? Part 2, The best hardware for the job

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