virtualbox.org

Hi. Not sure what I have done wrong, but since upgrading to Windows 8.1 none of my 64bit VM test servers work.

When I try to create a new Windows VM, in the drop down I have various flavours of Windows available, but all have '(32 bit)' appended to the description. So this probably explains why my 64bit VMs don't work.

This was OK when I was on Win 8.0 64bit, but now that I am on 8.1 64bit (yes, definitely on 64bit), nothing is working.

Just downloaded and installed 4.3.8, and the problem is now worse as I get a dialog box when starting a VM - failed to open a session - couldn't find the end of CPUID sub-leaves (VERR_CPUM_TOO_MANY_CPUID_SUBLEAVES).

Any suggestions on why my VirtualBox is not recognising that I am running on a 64bit machine and therefore should be able to run 64bit Windows.

Thanks.

James

I suspect (big guess) that this might have the same cause as the last three times it was reported.

http://lmgtfy.com/?q=VERR_CPUM_TOO_MANY ... ualbox.org

Only posted the error about VERR_CPUM_TOO_MANY_CPUID_SUBLEAVES as an after thought. This only happened when I updated to 4.3.8.

Previously, on 4.3.6, it tells me that I can't run a 64bit VM on my machine as virtualbox thinks it is only a 32bit OS, but it isn't. Think resolving this problem will sort out other problems - but may go back to 4.3.6 anyway.

James

Are you sure that you are not running hyper-v on the host?

Host is my laptop, running windows 8.1 64bit.

We don't use any virtual machines except for creating them to test out an upgrade and then kill it - like what I am trying to do is install Windows 2008R2 and upgrade it to Windows 2012, don't want to do it on my production servers and screw them up and my colleagues string me up

James

That still does not answer my question. hyper-v comes with win 8.1 by default. From the looks of it your machine has it enabled and that will cause this issue.

Sorry Perryg. If it is enabled as standard, then yes. Going to hunt to disable it.

James

how do you disbale hyper v in windows 8.1 did a google search cant find anything out there

Really?
I put "disable hyper-v windows 8" and got the following
https://www.google.com/search?channel=f ... 8&oe=utf-8