VirtualBox 4.3.20 for Windows Hosts

[LearnLinux]

I download the latest VirtualBox 4.3.20 for Windows Hosts with x86/amd64 and tried to install CentOS7 64 bit ISO. The virtualbox only provide 32bit OS options. My computer is running 64bits Windows 7 OS. Why can I see 64bits OS option from the drop down list?

Thanks,
LearnLinux

[socratis]

From the FAQ: I have a 64bit host, but can't install 64bit guests.

[LearnLinux]

Does anyone have an answer to this? Why can't I see the 64bits option on the VirtualBox? Is it because I am running Windows 7 64bits that it won't support it? I cannot find any posting related to this in this forum. Please help.

[mpack]

You have already been given a link to the FAQ, which certainly answers your question. What other help do you require?

[alexwh]

I am having the same problems.

My setup is Windows 8.1 x64 bit host. CPU is i5-4460. I cannot see any options for 64bit guests.

And yes, I have made sure that virtualization IS ON in my BIOS and my cpu is CAPABLE. Hyper-V is uninstalled.

Had virtualbox 4.3.12 installed originally (which worked perfectly) and upgraded to 4.3.20. All 64 guests options are now gone. When I create a dummy vm, go into settings -> system, the acceleration tab is now disabled too. I tried reverting back to 4.3.12 hoping I could get 64 bit guests back, but now that doesn't work either. Not sure what is going on.

I installed my copy of vmware and everything is fine, virtualization and 64 bit guests work perfect.

Any help would be great!

[mpack]

There is nothing to add to what's in the FAQ. If you don't see 64bit guest's being offered then you have not fulfilled one of the items on the checklist - it's up to you to check each item thoroughly.

If you want to discuss this further then provide a VM log file, ideally for a VM in which you turned on VT-x. Right click the VM in the GUI. Select "Show Log". Save "VBox.log" to a file. Compress that file and attach it to a message here.

[alexwh]

I posted this in the other thread, but my solution was to disable "Execution Prevention" in my BIOS. You might consider adding that as a solution in the FAQ.

[mpack]

No chance of that. The NX bit isn't relevant. Your true solution was probably that you did a full reboot of your PC when you changed the BIOS config. The need for the latter is covered in the FAQ.

[gg99]

and disable execution prevention indiscriminately is a security risk