Unable to start VirtualBox while KVM loaded

[Jerome Poulin]

Even with VT-x disabled VirtualBox won't start if KVM loaded, it says it wants to start in VMX_ROOT_MODE even if it's disabled, I checked in config file and changed every hardware acceleration to false:

...
  <Hardware version="2">
      <CPU count="1">
        <HardwareVirtEx enabled="false"/>
        <HardwareVirtExNestedPaging enabled="false"/>
        <HardwareVirtExVPID enabled="false"/>
        <PAE enabled="false"/>
      </CPU>
...

Did I forget an option?

[Sander van Leeuwen]

Yes, and that is very clearly documented. The warning also clearly tells you what to do: unload the KVM module.

This is not our problem: it's KVM's unwillingness to share your computer with any other hypervisor.

[Sander van Leeuwen]

To stress this *again*: VirtualBox's software virtualization will crash your computer if the CPUs are in VMX root mode. (64 bits host or 32 bits with PAE paging)