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Can I run 64-bit VM guests on a 32-bit host?

If I have a physical PC with 32 bit can I launch a VM that is 64 bit? What virtual machine software (Virtual PC or VirtualBox or other) would allow this?

I read out there that VMware may support this but I am looking for something Open source or free.

Host would preferably be a Windows host but could be Linux. Guest needs to be Windows.

Thanks

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6 Answers 6

up vote 10 down vote accepted

VirtualBox can run 64-bit guests on a 32-bit host. You'll need to make sure your processor has hardware virtualization and that it is enabled in the BIOS. You can find some extra information at the VirtualBox Forums

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Yes you can... as long as your CPU supports it .. here's an article that may help http://giwitech.blogspot.com/2010/03/tip-installing-64-bit-virtual-machine.html

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This is trickier than I thought before I was in the market for a box that can handle 64-bit guests.

Myth #1: All 64-bit hosts can run 64-bit guests. False. 64-bit guest requires specific hardware support: VT-x or AMD-V.

Myth #2: All 64-bit processors support 64-bit guests. False. See myth #1.

Myth #3: All current Intel 64-bit processors have VT-x. False. Many brand new 64-bit processors (T6400, T6500 etc.) do NOT support VT-x, in the name of market segmentation.

Myth #4: All machines with VT-x capable processor can support 64-bit guest. False. VT-x support is disabled by default on Intel processors and needs to be enabled by BIOS. Many BIOS, e.g., those in most Acer laptops, do NOT have the option to turn on VT-x.

Basically host OS is irrelevant w.r.t 64-bit guest. If you're looking for a cheap machine to run 64-bit guests, stick to current AMD Athlon 64 (with AM2 or AM3 sockets) or Opteron (2+ generations) processors, as AMD-V support is on by default.

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Depends what you mean by a "32-bit host". If you mean hardware with a 32-bit processor that doesn't have 64-bit capabilities, then no, you can't do that through virtualisation - you would need an emulator rather than virtualisation and I'm not aware of one existing.

If you mean on a machine with a 32-bit OS, then again, it's not possible to run a 64-bit guest on a 32-bit OS without emulation (something would need to translate the 64-bit instructions into 32-bit instructions) unless either (a) the 32-bit OS allows 64-bit applications (like Mac OS X) or (b) you can bypass the OS with a hypervisor. I'm not aware of a 32-bit type II virtualisation product for the Mac that allows a 64-bit OS to run as a 64-bit app. In fact, I'm not aware of a type II virtualisation product for the Mac at all.

If you're using a hypervisor (type I virtualisation) like Hyper-V, VMWare ESX, Virtual Box, etc, then it should be possible, because the guest OS does not run on the host OS, but on the hypervisor. Indeed, the "host" OS actually runs on the hypervisor too.

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With Virtual-Box, you need a more recent processor that supports VT-x and you need to turn that on in the BIOS.

Any combination of host and guest should work OK. Performance may not be as ideal as running under a 64bit host.

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Are there really 32 bit processors with VT support? –  Kara Marfia Sep 10 '09 at 14:13
4  
Not 32-bit processors no. But you could be running a 32-bit operating system on a 64-bit processor (which is pretty normal these days). If your processor is old enough not to have any support for 64-bit in the first place, there is no way to run a 64-bit guest. –  Joshua Sep 10 '09 at 14:20
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Most late-model 32 bit processors still do virtualization, but not with all the HyperVisor features enabled by VT-x. 32 bit processors are getting rare. You'd have to go back to four-five years to Socket 478 Pentium 4's, Pentium M, or AMD Athlon XP's (and pre-XP's) and earlier to be 32 bit. Even the Celeron went 64 bit with the Celeron D in 2005. –  kmarsh Sep 10 '09 at 15:46

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