Box64 — x86_64 Emulator for ARM64 and RISC-V Linux

Introduction

Box64 is a Linux userspace emulator that allows x86_64 applications to run on ARM64, RISC-V 64-bit, and LoongArch hardware. It uses a dynamic recompiler (dynarec) to translate x86_64 instructions to the host architecture at runtime, achieving performance levels that make desktop applications and even some 3D games playable on single-board computers and ARM laptops.

What Box64 Does

• Translates x86_64 machine code to ARM64, RV64, or LoongArch instructions at runtime
• Wraps native system libraries so x86_64 programs can call host libc, OpenGL, and Vulkan
• Integrates with binfmt_misc so x86_64 binaries launch transparently
• Supports Wine and Proton for running Windows applications on ARM hardware
• Handles multi-threaded applications and signal forwarding correctly

Architecture Overview

Box64 intercepts x86_64 instructions and either interprets them or feeds them to a platform-specific dynarec that emits native code blocks. Frequently executed code paths are cached in a translation buffer for reuse. For system library calls, Box64 has a wrapping mechanism that bridges x86_64 calling conventions to native ones, avoiding the overhead of emulating standard library code.

Self-Hosting & Configuration

• Build from source with CMake; enable the dynarec for your platform (ARM_DYNAREC, RV64_DYNAREC, etc.)
• Register the binfmt handler so x86_64 ELF binaries run automatically
• Set BOX64_LOG environment variable to control logging verbosity
• Use BOX64_LD_LIBRARY_PATH to point to x86_64 library directories
• Pair with Box86 (the 32-bit sibling) for i386 application support

Key Features

• Dynamic recompiler delivers playable performance for demanding applications
• Library wrapping avoids emulating well-known libraries, boosting speed
• Transparent binfmt integration requires no manual invocation
• Works with Wine and Proton to run Windows software on ARM devices
• Supports Raspberry Pi 4/5, Apple M-series (via Asahi Linux), Snapdragon, and RISC-V boards

Comparison with Similar Tools

• QEMU user-mode — general-purpose emulation with higher overhead; Box64 is optimised for performance via dynarec
• FEX-Emu — similar x86 on ARM emulator; Box64 focuses on library wrapping for speed
• Rosetta 2 — Apple's proprietary translation layer for macOS; Box64 is open-source and Linux-only
• Box86 — the 32-bit (i386) sibling project; use both together for full x86 support
• Wine + Hangover — combines Wine with QEMU for Windows apps on ARM; Box64 + Wine is generally faster

FAQ

Q: Can it run Steam games? A: Yes, with Wine or Proton. Many games are playable on Raspberry Pi 5 and similar hardware.

Q: How does performance compare to native? A: Typically 50-80% of native x86_64 speed depending on the workload and dynarec maturity.

Q: Does it support Vulkan? A: Yes. Box64 wraps Vulkan calls to the host driver, enabling DXVK and vkd3d-proton.

Q: Which ARM devices are supported? A: Any ARM64 Linux system: Raspberry Pi 4/5, Pine64, Rockchip, Snapdragon, and Apple Silicon via Asahi Linux.

Sources

• https://github.com/ptitSeb/box64
• https://box86.org