How to enable i386?

[vk496]

Is this a bug report, feature (enhancement) request or question? (leave only one on its own line)

/kind question

Description:

How can I register the qemu-static-i386?

Steps to reproduce the issue:

$ docker run --rm --privileged multiarch/qemu-user-static --reset -p yes          
Setting /usr/bin/qemu-alpha-static as binfmt interpreter for alpha
Setting /usr/bin/qemu-arm-static as binfmt interpreter for arm
Setting /usr/bin/qemu-armeb-static as binfmt interpreter for armeb
Setting /usr/bin/qemu-sparc32plus-static as binfmt interpreter for sparc32plus
Setting /usr/bin/qemu-ppc-static as binfmt interpreter for ppc
Setting /usr/bin/qemu-ppc64-static as binfmt interpreter for ppc64
Setting /usr/bin/qemu-ppc64le-static as binfmt interpreter for ppc64le
Setting /usr/bin/qemu-m68k-static as binfmt interpreter for m68k
Setting /usr/bin/qemu-mips-static as binfmt interpreter for mips
Setting /usr/bin/qemu-mipsel-static as binfmt interpreter for mipsel
Setting /usr/bin/qemu-mipsn32-static as binfmt interpreter for mipsn32
Setting /usr/bin/qemu-mipsn32el-static as binfmt interpreter for mipsn32el
Setting /usr/bin/qemu-mips64-static as binfmt interpreter for mips64
Setting /usr/bin/qemu-mips64el-static as binfmt interpreter for mips64el
Setting /usr/bin/qemu-sh4-static as binfmt interpreter for sh4
Setting /usr/bin/qemu-sh4eb-static as binfmt interpreter for sh4eb
Setting /usr/bin/qemu-s390x-static as binfmt interpreter for s390x
Setting /usr/bin/qemu-aarch64-static as binfmt interpreter for aarch64
Setting /usr/bin/qemu-aarch64_be-static as binfmt interpreter for aarch64_be
Setting /usr/bin/qemu-hppa-static as binfmt interpreter for hppa
Setting /usr/bin/qemu-riscv32-static as binfmt interpreter for riscv32
Setting /usr/bin/qemu-riscv64-static as binfmt interpreter for riscv64
Setting /usr/bin/qemu-xtensa-static as binfmt interpreter for xtensa
Setting /usr/bin/qemu-xtensaeb-static as binfmt interpreter for xtensaeb
Setting /usr/bin/qemu-microblaze-static as binfmt interpreter for microblaze
Setting /usr/bin/qemu-microblazeel-static as binfmt interpreter for microblazeel
Setting /usr/bin/qemu-or1k-static as binfmt interpreter for or1k

Describe the results you received:

List of different architectures that works perfectly

Describe the results you expected:

The i386 arch

Environment:

• QEMU version:
• Container application: Docker

Output of docker version, podman version or singularity version

docker version                    ✔  10066  17:36:04
Client: Docker Engine - Community
 Version:           19.03.1
 API version:       1.40
 Go version:        go1.12.5
 Git commit:        74b1e89e8a
 Built:             Thu Jul 25 21:17:37 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          19.03.1
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.12.5
  Git commit:       74b1e89e8a
  Built:            Thu Jul 25 21:27:55 2019
  OS/Arch:          linux/amd64
  Experimental:     true
 containerd:
  Version:          v1.2.7.m
  GitCommit:        85f6aa58b8a3170aec9824568f7a31832878b603.m
 runc:
  Version:          1.0.0-rc8
  GitCommit:        425e105d5a03fabd737a126ad93d62a9eeede87f
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

Additional information optionally:

[junaruga]

@vk496 good point! thanks for the feedback!

Certainly /usr/bin/qemu-i386-static is not included in the result of docker run --rm --privileged multiarch/qemu-user-static --reset -p yes .
But it actually works.

Which kind of Linux distribution's i386 container do you want to run?

If you want to run ubuntu's i386 container image, using i386/ubuntu image ( https://hub.docker.com/r/i386/ubuntu/ ) looks good.
Here is the i386 's case with the i386 image with the Travis CI.

You can refer this repository's "i386" case in .travis.yml.
https://github.com/junaruga/ci-multi-arch-test/blob/master/.travis.yml#L24-L27
https://travis-ci.org/junaruga/ci-multi-arch-test/jobs/567486350

file command shows 32-bit for the compiled binary on the environment.
bin/hello binary (C program to identity the environment) shows 32-bit.

$ file bin/hello
bin/hello: ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), dynamically linked, interpreter /lib, for GNU/Linux 3.2.0, BuildID[sha1]=48eb3582abea27022b746ae6587bda9767896eaf, not stripped

$ bin/hello
Hello World!
Endian Type: Little-endian
Bit: 32-bit
Sizeof {int, long, long long, void*, size_t, off_t}: {4, 4, 8, 4, 4, 4}

The tricky point is when uname command shows x86_64, it can be actually i386 environment depending on the environment.
Because there are 2 types of architectures (architecture by uname command and actual architecture such as used in a part of a deb or a RPM package name), though I do not understand it well.
Same CPU type's 32-bit binary can work on the 64-bit host environment.

When you want to run fedora i386 image, unfortunately it does not exist on both DockerHub and official container repo.
https://hub.docker.com/_/fedora
https://registry.fedoraproject.org/repo/fedora/tags/

[junaruga]

Debian, Alpine and CentOS has the i386 image too.
i386/debian : https://hub.docker.com/_/debian
i386/alpine : https://hub.docker.com/_/alpine
i386/centos : https://hub.docker.com/_/centos

If you just want to run 32-bit architecture's container, a Linux distribution's ARM-32 bit image can be the alternative of i386 such as arm32v7/fedora image: https://hub.docker.com/r/arm32v7/fedora/

[junaruga]

Searched keywords: i386, i686, Intel 32-bit

[vk496]

Thanks for your reply! I was interesting in compile native i386 code.

It was recently added with the docker/buildx#128 petition.

[junaruga]

Sure. Good news from docker buildx. I like it too. :)