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I am trying to create a new 64-bit Windows 7 virtual machine inside a 64-bit Debian 7.3.0 instance running in VirtualBox. I am allowed to run 32-bit machines, but I can not create 64-bit machines, as shown in the picture. Why is this? I have hardware virtualization enabled on the host.enter image description here

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marked as duplicate by Ƭᴇcʜιᴇ007 Oct 10 at 16:30

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Maybe because it's not turtles all the way down. –  Daniel R Hicks Sep 23 at 23:03

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I read this... "You must enable hardware virtualization for the particular VM for which you want 64-bit support; software virtualization is not supported for 64-bit VMs"

I am guessing since virtualbox is software, it will not support a 64-bit OS running from a 64-bit OS VM. That is my theory, maybe post system specs and what exactly is happening when you go to create another VM inside your VM.

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Bingo. A VM cannot provide hardware virtualization support since it isn't hardware. –  David Schwartz Feb 7 at 17:34
    
But there's no reason why hardware virtualization can't be simulated (other that, of course, performance, code size, memory, et al). –  Daniel R Hicks Sep 23 at 23:05

Let me get this straight. You have a host PC running VB. You then run 64bit Debian as a virtual machine. You then try to run a Windows VM inside the Debian VM?

Odd.

Well, @Snickerz is right, you need VM processor and BIOS support to run a 64bit VM, the Debian VM doesn't give you that. I suspect that the VB developers never thought it would be needed :)

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It's true that it is a bit of an odd setup. :) But I need to run some Linux software that again needs a virtual machine to work with, hence the machines inside the machines. –  user1049697 Feb 7 at 16:31
    
Fair enough - thought it might be something like that. You will have to live with 32bit and rubbish performance though I'm afraid. –  Julian Knight Feb 7 at 16:41
    
@user1049697 "run some Linux software that again needs a virtual machine to work with" You realize VB can have more than 1 virtual machine on the host, even at the same time. –  Robin Hood Sep 23 at 22:34
    
as Robin mentioned i would also use to vm's in the same host rather than a vm inside a vm. - the performance of the vm inside the vm earlier or later will drive you crazy –  konqui Sep 24 at 5:59

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