Why do I get "this CPU is not compatible with 64-bit mode" on a 64-bit processor?

Question

I have a 32-bit Ubuntu 10.10 as a host OS, VirtualBox 4.0, Windows 7 64-bit Professional as a guest OS. The laptop processor is 64-bit. When I try to load Windows 7 64-bit in VirtualBox, the error appears:

attempting to load a 64-bit application, however this CPU is not compatible with with 64-bit mode

I don't understand, the CPU is compatible with 64-bit mode, what's the problem?

Solution

I believe it's telling you VirtualBox's virtual CPU, though, is not 64-bit compatible. Is hardware virtualization enabled, and have you enabled VirtualBox's 64-bit support for the specific VM in question?

http://www.virtualbox.org/manual/ch03.html#intro-64bitguests

You need a 64-bit processor with hardware virtualization support (see the section called “Hardware vs. software virtualization”).

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.

Comments

[Diogo]

Please link us your processor name/model.

[Achu]

You must enable hardware virtualization through your BIOS

[Sergey]

Achu, how? I'm trying to google but I cannot find the answer.

[billc.cn]

Also observe this requirement: "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." Make sure you select an OS with "(64 bit)" in its name.

[Sergey]

I found it - my processor doesn't support hardware virtualization - that simple

[Ramhound]

You should read some of the other comments and answers. The author's hardware didn't support what he wanted to do. Furthermore he was using a 32-bit host operating system, and VirtualBox doesn't support a 64-bit operating system on a 32-bit host.