Thursday, September 13, 2012

Enabling 64-bit VMs on nested ESXi 5.1

In my home lab, I have a 2-node cluster with two virtual ESXi 5.1. When I tried to boot a 64-bit on these hosts I received the following error:

"Longmode is unsupported. It is required for 64-bit guest OS support. On Intel systems, longmode requires VT-x to be enabled in the BIOS. On nested virtual ESX hosts, longmode requires the "Virtualized Hardware Virtualization" flag to be enabled on the outer VM."

I seem to remember that in version 5.0 you had to configure a given parameter in the ESXi console. For ESXi 5.1 this has changed according to this VMware KB.

It states the following:

"Virtualized HV is fully  supported for virtual hardware version 9 VMs on hosts that support  Intel VT-x and EPT or AMD-V and RVI. To enable virtualized HV, use the web client and navigate to the processor settings screen. Check the  box next to  "Expose hardware-assisted virtualization to the guest operating system."  This setting is not available under the traditional C# client."

So, access the web client, locate the VM, right click -> Edit settings, and check the box as mentioned (for the parent VM, not the virtual ESXi...). It works like a charm, see screendump below:


  1. boo :'( this is greyed out on my Precision T7400 populated with dual Xeon E5420's even though Intel ARK lists it as having VT-x with EPT - any ideas?

    1. Also, you can read these two articles for inspiration:

    2. all enabled in bios, yes. I've got a PowerEdge 2950 with supposeldy-compatible cpu's but having the same issue. BIOS all flashed up to latest too

    3. Then it points to a software configuration issue. Two things:
      1. ensure that vHW of the VM running the ESXi 5.1 is upgraded to version 9
      2. Once the VM (with the hypervisor) has been created, go to Edit Settings -> Options -> Guest Operating System choose 'Other' and then choose VMware ESXi 5.x.

  2. How do get to the paraemter "Expose hardware-assisted virtualization to the guest operating system." without the web client?

    I am running ESX5.1 free edition on a physical box, but want to run virtual ESX guests.

    The must be a manual paremeter i can put in the vmx file?

    1. I read on another interesting article below which tells you about using the vhv.enable parameter


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