Hypervisor Mode
Recent CPUs from Intel and AMD offer x86 virtualization instructions for a hypervisor to control Ring 0 hardware access. Although they are mutually incompatible, both Intel VT-x (codenamed "Vanderpool") and AMD-V (codenamed "Pacifica") create a new "Ring -1" so that a guest operating system can run Ring 0 operations natively without affecting other guests or the host OS.
"To assist virtualization, VT and Pacifica insert a new privilege level beneath Ring 0. Both add nine new machine code instructions that only work at "Ring -1," intended to be used by the hypervisor. "
Read more about this topic: Ring (computer Security)
Famous quotes containing the word mode:
“I cannot believe that our factory system is the best mode by which men may get clothing. The condition of the operatives is becoming every day more like that of the English; and it cannot be wondered at, since, as far as I have heard or observed, the principal object is, not that mankind may be well and honestly clad, but, unquestionably, that the corporations may be enriched.”
—Henry David Thoreau (1817–1862)