- Robert P. Goldberg coined VMM architecture types:
- Type I or bare metal: The VMM runs on a bare machine.
- Type II or hosted: The VMM runs on an extended host, under the host operating system.
- Can be understood as:
- Type 1: No OS runs in the host-mode.
CPUID instructions ran by your OS would be intercepted by a hypervisor.
- Hyper-V, Xen: even "admin OS" runs in the guest-mode
- VMware ESXi, BitVisor: no "admin OS"
- CheatEngine, BluePill, antivirus-hypervisor: turns the current OS into guest-mode
- Type 2: A general purpose OS runs in the host-mode.
CPUID instructions ran by your OS would not be intercepted.
- KVM, VirtualBox, VMware Workstation: works as a kernel extension. The host OS runs in the host-mode
- Our hypervisor is type-1 (no admin OS)