How to enable VT-x/AMD-V ???

Discussions about using Windows guests in VirtualBox.

How to enable VT-x/AMD-V ???

Postby jmine83 » 3. Jun 2010, 01:16

I am attempting to install Windows Vista Ultimate 64-bit in VirtualBox, however I am encountering a problem that halts the Windows installation program from even executing; briefly described as follows:

< Windows Boot Manager >

Windows failed to start. A recent hardware or software change might be the cause ...

Info: Attempting to load a 64-bit application, however this CPU is not compatible with 64-bit mode.

I have conducted a wide variety of Google searches to invest a fix for this particular problem; resulting in only bits-and-pieces of information which don't explain "fully" how to resolve this problem. From what I have read, all I know is I somehow need to enable "VT-x/AMD-V" in the BIOS. However, what never seems to be clarified is whether this is referring to the BIOS of the virtual machine, or the BIOS of my actual, physical notebook PC. And if it is the BIOS of the virtual machine, then how do I enable "VT-x/AMD-V" or even access the BIOS of the virtual machine?

I would greatly appreciate some simple, straight forward assistance in this matter as quickly as possible.
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Re: How to enable VT-x/AMD-V ???

Postby BillG » 3. Jun 2010, 01:33

The problem is that, even if your CPU is capable of hardware virtualization, it is not available to the host OS unless the BIOS of the host machine also supports it.

If your host machine has a CPU which is capable, check the BIOS settings to see whether there is an option to enable hardware virtualization. Exactly what it is called depends on the BIOS you are using. If there is no option available, check to see if there is a newer version of the BIOS available. Remember to completely power off the machine after you upgrade the BIOS. A reboot is not adequate. (In some rare cases you need to actually remove the battery from a laptop fo the BIOS upgrade to stick).

You cannot install a 64-bit OS in the guest machine unless the CPU and the host's BIOS all support hardware virtualization. That is the only way that the guest OS can see a 64-bit capable CPU.
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Re: How to enable VT-x/AMD-V ???

Postby Sasquatch » 3. Jun 2010, 20:27

There is a section in the VirtualBox FAQ about it. The more advanced check is for Linux Host to see the CPU features, but Windows users can use CPU-z or similar.
Read the Forum Posting Guide before opening a topic.
VirtualBox FAQ: Check this before asking questions.
Online User Manual: A must read if you want to know what we're talking about.
Howto: Install Linux Guest Additions
Howto: Use Shared Folders on Linux Guest
See the Tutorials and FAQ section at the top of the Forum for more guides.
Try searching the forums first with Google and add the site filter for this forum.
E.g. install guest additions

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