QEMU is a generic and open source processor emulator 
which achieves a good emulation speed by using dynamic translation.

QEMU has two operating modes:

* Full system emulation. In this mode, QEMU emulates 
a full system (for example a PC), including a processor and 
various peripherals. It can be used to launch different
Operating Systems without rebooting the PC or to debug system code.

* User mode emulation (Linux host only). In this mode, 
QEMU can launch Linux processes compiled for one CPU on another CPU.