qemu

QEMU is a generic and open-source machine emulator and virtualizer. It can perform full-system emulation as well as user-mode emulation, allowing software compiled for one CPU architecture to run on a different host architecture. It supports a wide range of guest and host architectures, including x86_64, i386, ARM, AArch64, PowerPC, SPARC, MIPS, and RISCV.

In full-system emulation, QEMU models a complete hardware platform, including CPU, memory, and peripherals, and boots an operating system inside a virtual machine. It uses a dynamic translator called TCG (Tiny Code Generator) to translate guest code on the fly. When the host supports virtualization, QEMU can employ the KVM kernel module to accelerate guest execution, delivering near-native performance.

In user-mode emulation, QEMU executes individual programs compiled for one architecture on another by translating system calls and emulating necessary libraries at the process level. It presents a POSIX-compatible interface and can run foreign-architecture binaries transparently to the user.

QEMU includes a rich set of device models and supports virtio drivers, PCI, USB, SCSI, and other peripherals. It provides a configurable virtual machine environment with support for disk images (qcow2, raw, and others), networking, graphics, and console access. It supports live migration, snapshots, and various boot methods, including UEFI via the OVMF project.

The project is free and open-source software released under the GNU General Public License (GPL) version 2 or later. It is widely used in virtualization stacks and cloud platforms, frequently in combination with KVM and management tools such as libvirt. QEMU originated in 2003, created by Fabrice Bellard, and remains a central tool for cross-architecture development and testing.