OStatic

QEMU is a processor emulator that relies on dynamic binary translation to achieve a reasonable speed while being easy to port on new host CPU architectures. In conjunction with CPU emulation, it also provides a set of device models, allowing it to run a variety of unmodified guest operating systems, thus is can be viewed as a hosted virtual machine monitor. It also provides an accelerated mode for supporting a mixture of binary translation (for kernel code) and native execution (for user code), in the same fashion as VMware Workstation and Microsoft Virtual PC. Qemu can also be used purely for CPU emulation for user level processes, in this mode of operation, it is most similar to valgrind.

When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, it achieves very good performances.

When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. A host driver called the QEMU accelerator (also known as KQEMU) is needed in this case. The virtualizer mode requires that both the host and guest machine use x86 compatible processors.