text: Intel virtualization (VT-x) Previously codenamed "Vanderpool", VT-x represents Intel's technology for virtualization on the x86 platform. On November 13, 2005, Intel released two models of Pentium 4 (Model 662 and 672) as the first Intel processors to support VT-x. The CPU flag for VT-x capability is "vmx"; in Linux, this can be checked via /proc/cpuinfo, or in macOS via sysctl machdep.cpu.features.
  "VMX" stands for Virtual Machine Extensions, which adds 13 new instructions: VMPTRLD, VMPTRST, VMCLEAR, VMREAD, VMWRITE, VMCALL, VMLAUNCH, VMRESUME, VMXOFF, VMXON, INVEPT, INVVPID, and VMFUNC. These instructions permit entering and exiting a virtual execution mode where the guest OS perceives itself as running with full privilege (ring 0), but the host OS remains protected.
  , almost all newer server, desktop and mobile Intel processors support VT-x, with some of the Intel Atom processors as the primary exception. With some motherboards, users must enable Intel's VT-x feature in the BIOS setup before applications can make use of it.
  Intel started to include Extended Page Tables (EPT), a technology for page-table virtualization, since the Nehalem architecture, released in 2008. In 2010, Westmere added support for launching the logical processor directly in real mode a feature called "unrestricted guest", which requires EPT to work.
  Since the Haswell microarchitecture (announced in 2013), Intel started to include VMCS shadowing as a technology that accelerates nested virtualization of VMMs.