• VM: Oracle VirtualBox 4.0.10 r72479
  • Host OS: Windows 7 64-bit
  • Guest OS: CentOS 5.6 64-bit

Downloaded a ready-made image of the guest OS from here.

When running, CentOS tells me:

Your CPU does not support long mode. Use a 32bit distribution.

CentOS's error message

Also mounting the original distribution's DVD doesn't work.
What's wrong? It happened me before with other OSs (in VirtualBox only) but now I actually need that.

Any way to resolve this or should I use another VM tool? Google search doesn't give much.

Edit #1
Some of my system's details:

CPU Type: DualCore Intel Core 2 Duo E7300, 2666 MHz (10 x 267)
Motherboard Name: Asus P5KPL-CM (2 PCI, 1 PCI-E x1, 1 PCI-E x16, 2 DDR2 DIMM, Audio, Video, Gigabit LAN)
Motherboard Chipset: Intel Bearlake G31
BIOS Type: AMI (01/26/08)


Does your host machine have hardware virtualization support (VT-x/AMD-V), is that support enabled in the host BIOS, and is the option for hardware assisted virtualization checked in the virtual machine configuration?

Having working VT-x/AMD-V is a requirement for running a 64-bit guest.

  • Hi stephen! I've got into my BIOS in order to check if I have there anything related to virtualization but I couldn't find anyhthing. Anyway at Edit #1 you can see my system's details. Could you tell if it's a compatible one? How/Where do I check that? I'm totally lost in this area.. Thanks a lot! – Poni Jul 15 '11 at 14:09
  • Nevermind, found the answer to that :/ Thank you anyway ! – Poni Jul 15 '11 at 15:12

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.