# About QEMU

QEMU is a generic and open source machine emulator and virtualizer.

QEMU can be used in several different ways. The most common is for “system emulation”, where it provides a virtual model of an entire machine (CPU, memory and emulated devices) to run a guest OS. In this mode the CPU may be fully emulated, or it may work with a hypervisor such as KVM, Xen, Hax or Hypervisor.Framework to allow the guest to run directly on the host CPU.

The second supported way to use QEMU is “user mode emulation”, where QEMU can launch processes compiled for one CPU on another CPU. In this mode the CPU is always emulated.

QEMU also provides a number of standalone commandline utilities, such as the `qemu-img` disk image utility that allows you to create, convert and modify disk images.

- Supported build platforms
  - Supported host architectures
  - Linux OS, macOS, FreeBSD, NetBSD, OpenBSD
  - Windows
- Deprecated features
  - System emulator command line arguments
  - QEMU Machine Protocol (QMP) commands
  - System accelerators
  - Host Architectures
  - QEMU API (QAPI) events
  - System emulator machines
  - Backend options
  - Device options
  - Backwards compatibility
  - Tools
  - QEMU guest agent
- Removed features
  - System emulator command line arguments
  - QEMU Machine Protocol (QMP) commands
  - Human Monitor Protocol (HMP) commands
  - Guest Emulator ISAs
  - System emulator CPUS
  - System emulator machines
  - linux-user mode CPUs
  - TCG introspection features
  - System emulator devices
  - Related binaries
  - Block devices
- License