gem5 vs QEMU
gem5
gem5.org
QEMU
qemu.orgSide by side
| Figure | gem5 | QEMU |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | Yes |
| Windows | — | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| API | — | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 2 |
| Spec score · Emulator Software | 7.8 (#24) | 8.5 (#9) |
| Build requirements | The building guide lists GCC version 10 or later, up to version 13, and says Clang is also supported. | QEMU 11.1.50 requires at least Python 3.9 and Rust 1.83.0 for supported builds. |
| License | The simulator is released under a Berkeley-style open-source license, with portions derived from other sources subject to their original licenses. | QEMU and its manual are released under GNU General Public License version 2, although some components have specific licenses. |
| Purpose | gem5 is a modular platform for computer-system architecture research, covering system-level architecture and processor microarchitecture. | QEMU is a generic and open source machine emulator and virtualizer. |
Plans
In their own words
QEMU
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.