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x64 support in ESXi4.1 requires VT, I know that! but why warn so late?

Posted by jpluimers on 2010/08/16

I know that ESXi 4.1 requires VT (the Intel support for hardware assisted virtualization) to be enabled to run x64 VMs.
This is the warning that you get when starting an x64 VM, and you don’t have VT enabled:

[Window Title]
Virtual Machine Message
[Main Instruction]
Virtual Machine Message
msg.cpuid.noLongmodeQuestionFmt: This virtual machine is configured for 64-bit guest
operating systems. However, 64-bit operation is not possible.
This host is VT-capable, but VT is disabled.
VT might be disabled if it has been disabled in the BIOS settings or the host has not been
power-cycled since changing this setting.
(1) Verify that the BIOS settings enable VT and disable ‘trusted execution.’
(2) Power-cycle the host if either of these BIOS settings have been changed.
(3) Power-cycle the host if you have not done so since installing VMware ESX.
(4) Update the hosts’s BIOS to the latest version.
For more detailed information, see
Continue without 64-bit support?
[Yes] [No] [OK]

Following the link, you will see the page on the right.
In large friendly letters, it shows (even when you are logged on in your VMware account):

You are not authorized to access this Document.

A few points:

  1. Why can’t it warn me upon installation?
    It helps x86 as well as x64, so an early warning would be very nice.
    Now you have to power down the machine (which might already be running a few x86 VMs), change the BIOS settings, then reboot.
    Inconvenient when the machine is not near (like: in a data center)…
  2. Why the error message in stead of more details?
    People not knowing about VT certainly need some extra explanation.

In the mean time, I found out that one of my two HP XW6600 boxes had different BIOS settings than the other.
That was no problem for running Windows 7 Ultimate x64 on it, but ESXi requires the VT to be enabled.

Note the HP XW6600 have been on the market long enough to use as a white box.
It is not on the unofficual ESXi whitebox list yet, but I’ve been running it a while with ESXi 4 now, and just installed ESXi 4.1 on it, so I’ll blog about it in more detail later.


via VMware Communities: vCenter 4.1 in ESXi4.1 in Fusion 3.1? ….

3 Responses to “x64 support in ESXi4.1 requires VT, I know that! but why warn so late?”

  1. […] a HP XW6600, you can run ESXi 4 or run ESXi 5, but in yourder to run x64 guest VMs, you need to enable Intel VT in the BIOS […]

  2. Klauss said

    How did you make it work with vmware esxi 4.1? Have you tried esxi 5.x?

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