# Virtualbox: 64bit guest OS on AMD64 host

## kdvgent

I do not seem to be able to get this working.

I am using gentoo-sources-2.6.34 and virtualbox-ose-3.2.0-r1.

When I compile in my kernel KVM support (kvm) and KVM support for AMD processors - AMD-V (kvm-amd), the virtualbox (and the rest of the computer) freezes, one of my cpus indicate 100% activity and the only way out seem to be a hard reset of the computer. Searching on the Internet, it seems that this is caused because kvm-amd is loaded.

Without these options compiled in my kernel, virtualbox says when I start the guest OS that my computer has no AMD-V enabled and the guest OS cannot be started (claiming that no 64bit cpu can be found).

How to get out of this?

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## cach0rr0

KVM is unrelated to virtualbox, so you should not need that module/driver

If your CPU supports it, you should have one of these flags in /proc/cpuinfo

```

# egrep '(svm|vmx)' /proc/cpuinfo |uniq

```

if that returns nothing, you cannot run a 64bit guest with virtualbox

Now it may be possible that your processor does support it, but that the option simply isn't enabled in the BIOS. You need AMD-V or Intel-VT enabled in the BIOS if your processor supports it. 

So I suppose that's a worthwhile question to ask actually, what's the make/model of your CPU?

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## kdvgent

cach0rr0 - thanks for your suggestions.

I am not at home at present and I have no access to my computer but I have an AMD Phenom quad-core that supports AMD-V technology.

I checked /proc/cpuinfo and svm is there and virtualisation is enable in the BIOS.

Hence I seem to have all preconditions fulfilled but things do not work - and that is why I am puzzled.

To my knowledge, there is no other place in the kernel configuration that mentions virtualization except the part on KVM (that I also believe I do not need). Correct?

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## raddaqii

 *kdvgent wrote:*   

> cach0rr0 - thanks for your suggestions.
> 
> I am not at home at present and I have no access to my computer but I have an AMD Phenom quad-core that supports AMD-V technology.
> 
> I checked /proc/cpuinfo and svm is there and virtualisation is enable in the BIOS.
> ...

 

I encountered a similar problem, and yes, KVM is not needed. Found this BIOS-related bug over at virtualbox: http://www.virtualbox.org/ticket/5639 the summary of which is:

 *Quote:*   

> killall VBoxSVC
> 
> export VBOX_HWVIRTEX_IGNORE_SVM_IN_USE=true
> 
> VirtualBox
> ...

 

That thread is old, and primarily refers to Windows 7's compatibility mode, but solves the problem for people with Linuxes as well. Seems some BIOSes are just broken and that workaround is useful. YMMV, use at your own risk.

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