Is it possible to run Windows 7 64 bit from a 32bit ubuntu OS?
I can reinstall Ubuntu as a 64bit OS, but would prefer not to if it is not necessary.
From VB help:
VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems, provided that the following conditions are met:
1.-You need a 64-bit processor with hardware virtualization support (see Section 10.3, “Hardware vs. software virtualization”).
2.-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.
3.-If you want to use 64-bit guest support on a 32-bit host operating system, you must also select a 64-bit operating system for the particular VM. Since supporting 64 bits on 32-bit hosts incurs additional overhead, VirtualBox only enables this support upon explicit request.
On 64-bit hosts (which typically come with hardware virtualization support), 64-bit guest operating systems are always supported regardless of settings, so you can simply install a 64-bit operating system in the guest.
For Virtual Box, here's the Virtual Box FAQ:
Note that VirtualBox also supports 64-bit guest operating systems, under the following conditions:
- You need a 64-bit processor with hardware virtualization support (VT-x or AMD-V)
- Since version 2.1.0, you can run 64 bit Guests while running a 32 bit Host.
- You must enable hardware virtualization through your BIOS
So it depends on your CPU. Just having a 64-bit processor isn't sufficient, the CPU also needs hardware virtualization support.
As an example, the Intel i3 540 is listed as having "Intel® Virtualization Technology (VT-x): yes", so it should work there.
If your BIOS and processor support it, then yes. I'd suggest using hardinfo to check your processor's features. However you are better off using the 64bit OS as host anyway.
Even if you processor supports VTx your BIOS may not (many HP laptops for example do not allow you to turn this on), so you have to know if your BIOS also supports it.
I found that on my Ubuntu Lucid (32bit install) machine that it will complain that hardware virtualization is not turned on when it really is. The reason it does this is because the kvm module is loaded. I blacklisted kvm and kvm_amd and now Virtualbox loads up 64 bit guests on a 32bit host just fine.