Bochs vs QEMU

Bochs is a free, open-source emulator that models IA-32 x86 PC hardware. It can simulate Intel CPU families from 386 through x86-64, common I/O devices, and a custom BIOS, allowing users to run guest systems such as Linux, DOS, Windows, BSD, and other x86 operating systems. Optional command-line and graphical debuggers provide ways to inspect registers and memory or set breakpoints. Graphics support includes VGA, VESA VBE resolutions up to 2560x1600x32bpp, Cirrus Logic video, and four 3dfx Voodoo adapter models. Bochs also emulates USB controllers and devices, and can forward guest network packets to a physical network on several host systems. Multiprocessor simulation can be configured for up to 254 processor threads, but is experimental. The emulator uses a single-threaded simulation core and does not use dynamic code translation or virtualization. It supplies virtual hardware, not a setup wizard or guest installation disk, so users install guest systems themselves. Binary packages and source compilation are options; some features may require compiling it. It is available for Windows, Linux, and macOS, among other documented host systems.

QEMU is a free, open-source machine emulator and virtualizer. System emulation models an entire machine, including its CPU, memory and devices, so it can run a guest operating system. User-mode emulation runs processes built for one CPU architecture on another. The package also includes qemu-img, a command-line utility for creating, converting and modifying disk images. QEMU can work with KVM, Xen and Hypervisor.Framework so guests can run directly on the host CPU. Supported build platforms include Linux, macOS, FreeBSD, NetBSD, OpenBSD and Windows. Windows support is limited to 64-bit, while macOS requires the newest version currently available; support for the prior version is eventually dropped. For complex networking and storage configurations, the project recommends management tools such as virt-manager. Its security guidance distinguishes virtualization with an accelerator and listed machine type from TCG non-virtualization use, which does not provide guest-isolation or security guarantees. QEMU is released under GNU GPL version 2, with some components under specific licenses.