On Wed, Jul 14, 2010 at 02:20:10PM -0500, Victor Padro wrote: > they're not explicit as I stated but perhaps it just states as VT-D or > something that you may overlooked it. VT-d (Virtualization Technology for Directed I/O) is virtualization for devices. With this it's possible for a guest OS to have direct exclusive access to hardware devices (maybe one of the USB controllers, or a disk controller). This is, really, a layer violation but it can be a performance gain or allow VMs to access hardware that the hypervisor can not emulate. My machine, apparently, supports VT-d in the BIOS but either the chipset (H55) doesn't support it or something else is wrong; the capability isn't available to the hypervisor. This isn't needed for CPU virtualization to work. -- rgds Stephen