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x86 virtualization in your browser, recompiling x86 to wasm on the fly

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v86 emulates an x86-compatible CPU and hardware. Machine code is translated to WebAssembly modules at runtime in order to achieve decent performance. Here's a list of emulated hardware:

  • An x86-compatible CPU. The instruction set is around Pentium III level, including full SSE2 support. Some features are missing, in particular:
    • Task gates, far calls in protected mode
    • Some 16 bit protected mode features
    • Single stepping (trap flag, debug registers)
    • Some exceptions, especially floating point and SSE
    • Multicore
    • PAE
    • 64-bit extensions
  • A floating point unit (FPU). Calculations are done using the Berkeley SoftFloat library and therefore should be precise (but slow). Trigonometric and log functions are emulated using 64-bit floats and may be less precise. Not all FPU exceptions are supported.
  • A floppy disk controller (8272A).
  • An 8042 Keyboard Controller, PS2. With mouse support.
  • An 8254 Programmable Interval Timer (PIT).
  • An 8259 Programmable Interrupt Controller (PIC).
  • Partial APIC support.
  • A CMOS Real Time Clock (RTC).
  • A generic VGA card with SVGA support and Bochs VBE Extensions.
  • A PCI bus. This one is partly incomplete and not used by every device.
  • An IDE disk controller.
  • An NE2000 (8390) PCI network card.
  • A virtio filesystem.
  • A SoundBlaster 16 sound card.


Arch LinuxDamn Small LinuxBuildroot LinuxReactOSWindows 2000Windows 98Windows 95Windows 1.01MS-DOSFreeDOSFreeBSDOpenBSD9frontHaikuOberonKolibriOSQNX


Here's an overview of the operating systems supported in v86:

  • Linux works pretty well. Neither 64-bit nor PAE kernels are supported.
    • Damn Small Linux (2.4 Kernel) works.
    • All tested versions of TinyCore work.
    • BuildRoot can be used to build a minimal image. humphd/browser-vm has some useful scripts for building one.
    • Archlinux works. See for building an image.
    • Debian works. An image can be built from a Dockerfile, see tools/docker/debian/.
    • Alpine Linux works.
  • ReactOS works.
  • FreeDOS, Windows 1.01 and MS-DOS run very well.
  • KolibriOS works.
  • Haiku works.
  • Android x86 1.6-r2 works if one selects VESA mode at the boot prompt. Newer versions haven't been tested.
  • Windows 1, 3.0, 95, 98, ME and 2000 work. Other versions currently don't (see #86, #208).
    • In Windows 2000 and higher the PC type has to be changed from ACPI PC to Standard PC
  • Many hobby operating systems work.
  • 9front works.
  • Plan 9 doesn't work.
  • QNX works.
  • OS/2 doesn't work.
  • FreeBSD works.
  • OpenBSD works with a specific boot configuration. At the
    prompt type
    boot -c
    , then at the
    disable mpbios
  • NetBSD works only with a custom kernel, see #350.
  • SerenityOS doesn't work due to missing PAE support.

You can get some infos on the disk images here:

How to build, run and embed?

You need:

  • java (for Closure Compiler, not necessary when using
  • make
  • gcc and libc-i386 for building some of the test binaries
  • nasm, gdb and qemu-system (for running tests)
  • rust-nightly with the wasm32-unknown-unknown target
  • A version of clang compatible with rust-nightly
  • nodejs (a recent version is required, 10.11.0 is known to be working)


for a full setup on Debian.
  • Run
    to build the debug build (at
  • Run
    make all
    to build the optimized build (at
  • ROM and disk images are loaded via XHR, so if you want to try out
    locally, make sure to serve it from a local webserver. You can use
    make run
    to serve the files using Python's http module.
  • If you only want to embed v86 in a webpage you can use libv86.js. For usage, check out the examples.

Alternatively, to build using docker

  • If you have docker installed, you can run the whole system inside a container.
  • See
    to find Dockerfile required for this.
  • You can run
    docker build -f tools/docker/exec/Dockerfile -t v86:alpine-3.14 .
    from the root directory to generate docker image.
  • Then you can simply run
    docker run -it -p 8000:8000 v86:alpine-3.14
    to start the server.
  • Check
    for hosted server.


The disk images for testing are not included in this repository. You can download them directly from the website using:

wget -P images/{linux.iso,linux4.iso,buildroot-bzimage.bin,openbsd-floppy.img,kolibri.img,windows101.img,os8.img,freedos722.img}

Run all tests:

make jshint rustfmt kvm-unit-test nasmtests nasmtests-force-jit expect-tests jitpagingtests qemutests rust-test tests

See tests/ for more infos.

API examples

Using v86 for your own purposes is as easy as:

var emulator = new V86Starter({
    screen_container: document.getElementById("screen_container"),
    bios: {
        url: "../../bios/seabios.bin",
    vga_bios: {
        url: "../../bios/vgabios.bin",
    cdrom: {
        url: "../../images/linux.iso",
    autostart: true,

See starter.js.


v86 is distributed under the terms of the Simplified BSD License, see LICENSE. The following third-party dependencies are included in the repository under their own licenses:


More questions?

Shoot me an email to

[email protected]
. Please report bugs on GitHub.


Fabian Hemmer (,

[email protected]

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