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https://github.com/multiarch/qemu-user-static

:earth_africa: `/usr/bin/qemu-*-static`
https://github.com/multiarch/qemu-user-static

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:earth_africa: `/usr/bin/qemu-*-static`

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# qemu-user-static



[![License](https://img.shields.io/github/license/multiarch/qemu-user-static.svg?style=flat-square)](./LICENSE) ![actions](https://github.com/multiarch/qemu-user-static/workflows/actions/badge.svg) [![Releases](https://img.shields.io/github/commits-since/multiarch/qemu-user-static/latest.svg?style=flat-square)](https://github.com/multiarch/qemu-user-static/releases) [![Docker Hub](https://img.shields.io/docker/pulls/multiarch/qemu-user-static.svg?style=flat-square)](https://hub.docker.com/r/multiarch/qemu-user-static/)



![](https://raw.githubusercontent.com/multiarch/dockerfile/master/logo.jpg)



**multiarch/qemu-user-static** is to enable an execution of different multi-architecture containers by QEMU [1](#ref-1) and binfmt_misc [2](#ref-2).

Here are examples with Docker [3](#ref-3).



## Getting started



```

$ uname -m

x86_64



$ docker run --rm -t arm64v8/ubuntu uname -m

standard_init_linux.go:211: exec user process caused "exec format error"



$ docker run --rm --privileged multiarch/qemu-user-static --reset -p yes



$ docker run --rm -t arm64v8/ubuntu uname -m

aarch64

```



It works on many architectures and OS container images.



```

$ docker run --rm -t arm32v6/alpine uname -m

armv7l



$ docker run --rm -t ppc64le/debian uname -m

ppc64le



$ docker run --rm -t s390x/ubuntu uname -m

s390x



$ docker run --rm -t arm64v8/fedora uname -m

aarch64



$ docker run --rm -t arm32v7/centos uname -m

armv7l



$ docker run --rm -t ppc64le/busybox uname -m

ppc64le



$ docker run --rm -t i386/ubuntu uname -m

x86_64

```



Podman [4](#ref-4) also works.



```

$ sudo podman run --rm --privileged multiarch/qemu-user-static --reset -p yes



$ podman run --rm -t arm64v8/fedora uname -m

aarch64

```



Singularity [5](#ref-5) also works.



```

$ sudo singularity run docker://multiarch/qemu-user-static --reset -p yes



$ singularity run --cleanenv docker://arm64v8/fedora uname -m

aarch64

```



## Usage



### multiarch/qemu-user-static images



multiarch/qemu-user-static images are managed on the [Docker Hub](https://hub.docker.com/r/multiarch/qemu-user-static/) container repository.

The images have below tags.



**Images**



1. `multiarch/qemu-user-static` image

2. `multiarch/qemu-user-static:$version` images

3. `multiarch/qemu-user-static:$from_arch-$to_arch` images

4. `multiarch/qemu-user-static:$from_arch-$to_arch-$version` images

5. `multiarch/qemu-user-static:$to_arch` images

6. `multiarch/qemu-user-static:$to_arch-$version` images

7. `multiarch/qemu-user-static:register` image



**Variables**



* `$version`: Based QEMU's version.

* `$from_arch`: Host architecture

* `$to_arch`: Guest architecture



**Description**



* `multiarch/qemu-user-static` image container includes both a register script to register binfmt_misc entries and all the `/usr/bin/qemu-$arch-static` binary files in the container in it. `multiarch/qemu-user-static` image is an alias of the latest version of `multiarch/qemu-user-static:$version` images.

* `multiarch/qemu-user-static:$to_arch` images are aliases of `multiarch/qemu-user-static:x86_64-$to_arch`. `multiarch/qemu-user-static:$to_arch` images only include the `$to_arch`'s `/usr/bin/qemu-$to_arch-static` binary file in it. `multiarch/qemu-user-static:$to_arch` image is an alias of the latest version of `multiarch/qemu-user-static:$to_arch-$version` images.

* `multiarch/qemu-user-static:register` image has only the register script binfmt_misc entries.



`multiarch/qemu-user-static` and `multiarch/qemu-user-static:register` images execute the register script that registers below kind of `/proc/sys/fs/binfmt_misc/qemu-$arch` files for all supported processors except the current one in it when running the container. See binfmt_misc manual [2] for detail of the files.

As the `/proc/sys/fs/binfmt_misc` are common between host and inside of container, the register script modifies the file on host.



```

$ cat /proc/sys/fs/binfmt_misc/qemu-$arch

enabled

interpreter /usr/bin/qemu-$arch-static

flags: F

offset 0

magic 7f454c460201010000000000000000000200b700

mask ffffffffffffff00fffffffffffffffffeffffff

```



The `--reset` option is implemented at the register script that executes `find /proc/sys/fs/binfmt_misc -type f -name 'qemu-*' -exec sh -c 'echo -1 > {}' \;` to remove binfmt_misc entry files before register the entry.

When same name's file `/proc/sys/fs/binfmt_misc/qemu-$arch` exists, the register command is failed with an error message "sh: write error: File exists".



```

$ docker run --rm --privileged multiarch/qemu-user-static [--reset][--help][-p yes][options]

```



On below image, we can not specify `-p yes` (`--persistent yes`) option. Because an interpreter's existance is checked when registering a binfmt_misc entry. As the interpreter does not exist in the container, the register script finishes with an error.



```

$ docker run --rm --privileged multiarch/qemu-user-static:register [--reset][--help][options]

```



Then the register script executes QEMU's [scripts/qemu-binfmt-conf.sh](https://github.com/qemu/qemu/blob/master/scripts/qemu-binfmt-conf.sh) script with options.

You can check `usage()` in the file about the options.



```

Usage: qemu-binfmt-conf.sh [--qemu-path PATH][--debian][--systemd CPU]

                           [--help][--credential yes|no][--exportdir PATH]

                           [--persistent yes|no][--qemu-suffix SUFFIX]

       Configure binfmt_misc to use qemu interpreter

       --help:        display this usage

       --qemu-path:   set path to qemu interpreter ($QEMU_PATH)

       --qemu-suffix: add a suffix to the default interpreter name

       --debian:      don't write into /proc,

                      instead generate update-binfmts templates

       --systemd:     don't write into /proc,

                      instead generate file for systemd-binfmt.service

                      for the given CPU. If CPU is "ALL", generate a

                      file for all known cpus

       --exportdir:   define where to write configuration files

                      (default: $SYSTEMDDIR or $DEBIANDIR)

       --credential:  if yes, credential and security tokens are

                      calculated according to the binary to interpret

       --persistent:  if yes, the interpreter is loaded when binfmt is

                      configured and remains in memory. All future uses

                      are cloned from the open file.

```



You can run `/usr/bin/qemu-$arch-static` binary file` in the container.



```

$ docker run --rm -t multiarch/qemu-user-static:x86_64-aarch64 /usr/bin/qemu-aarch64-static -help

usage: qemu-aarch64 [options] program [arguments...]

Linux CPU emulator (compiled for aarch64 emulation)

...



$ docker run --rm -t multiarch/qemu-user-static:x86_64-aarch64 /usr/bin/qemu-aarch64-static -version

qemu-aarch64 version 4.0.0 (qemu-4.0.0-5.fc31)

Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers



$ docker run --rm -t multiarch/qemu-user-static:aarch64 /usr/bin/qemu-aarch64-static -help

usage: qemu-aarch64 [options] program [arguments...]

Linux CPU emulator (compiled for aarch64 emulation)

...



$ docker run --rm -t multiarch/qemu-user-static:aarch64 /usr/bin/qemu-aarch64-static -version

qemu-aarch64 version 4.0.0 (qemu-4.0.0-5.fc31)

Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers

```



`multiarch/qemu-user-static:$from_arch-$to_arch` images are used with `multiarch/qemu-user-static:register` image.

Because when the binfmt_misc entry is registered without `-p` option, the interpreter needs to be put in the container.



```

$ docker run --rm --privileged multiarch/qemu-user-static:register --reset



$ docker build --rm -t "test/integration/ubuntu" -<[1] QEMU: https://www.qemu.org/

* [2] binfmt_misc: https://www.kernel.org/doc/html/latest/admin-guide/binfmt-misc.html

* [3] Docker: https://www.docker.com/

* [4] Podman: https://podman.io/

* [5] Singularity: https://sylabs.io/singularity/