Running amd64 Linux (Docker) containers with FEX

[DarkoGNU]

Hello,

Is it possible now (probably not)? If not - what are the obstacles to running Linux containers with FEX?

I have already tried Podman and Docker, but they don't work - the error is the same for both:

ubuntu@test:/opt/seafile/seafile-server-latest$ docker run --name seafile-pro seafileltd/seafile-pro-mc:10.0.3-testing
WARNING: The requested image's platform (linux/amd64) does not match the detected host platform (linux/arm64/v8) and no specific platform was requested
exec /sbin/my_init: no such file or directory

[Sonicadvance1]

I'm not familiar with how Docker and Podman work so I can't say for sure.
Anything that is doing filesystem management, Linux namespaces, or a VM will be difficult to run under FEX.
Not saying it is impossible but unless someone knows the details of those projects it might be really difficult.

[EliaCereda]

Sorry for reviving an old discussion, but this is possible pretty easily and it's the main reason I've been using FEX for a couple of years. I'm sure it might be useful also for other people.

FEX can be used to run unmodified amd64 Docker images as long as binfmt support is installed (fex-emu-binfmt32 and/or fex-emu-binfmt64). Docker must be explicitly instructed to run an amd64 image even though it does not match the host platform and a handful of files (FEX executables and arm64 shared libraries) must be mounted inside the container so that FEX can run.

$ uname -a
Linux docker-vm 5.19.17-051917-generic #202210240939 SMP PREEMPT_DYNAMIC Mon Oct 24 13:56:02 UTC 2022 aarch64 aarch64 aarch64 GNU/Linux
$ dpkg -l | grep fex
ii  fex-emu-armv8.4                             2407~1~j                                arm64        x86 and x86-64 Linux emulator
ii  fex-emu-binfmt32                            2407~1~j                                arm64        x86 and x86-64 Linux emulator
ii  fex-emu-binfmt64                            2407~1~j                                arm64        x86 and x86-64 Linux emulator
ii  libfex-emu-armv8.4-dev                      2407~1~j                                arm64        x86 and x86-64 Linux emulator
$ docker run \
    --platform linux/amd64 \
    -v/lib/ld-linux-aarch64.so.1:/lib/ld-linux-aarch64.so.1:ro \
    -v/lib/aarch64-linux-gnu:/lib/aarch64-linux-gnu:ro \
    -v/usr/bin/FEXInterpreter:/usr/bin/FEXInterpreter:ro \
    -v/usr/bin/FEXLoader:/usr/bin/FEXLoader:ro \
    -v/usr/bin/FEXServer:/usr/bin/FEXServer:ro \
     hello-world

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
 https://hub.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/get-started/

[Radiicall]

Does this still work for you? I tried in distrobox with podman with the same mounts and had errors with locating libstdc++.so.6.
Happened with ubuntu and fedora images

[EliaCereda]

Yes this works for me across different image versions. Sounds more of a problem with the host system than with the images. My host system is Ubuntu 22.04 arm64 running in VMware Fusion.

$ docker run --rm -it --platform linux/amd64 -v/lib/ld-linux-aarch64.so.1:/lib/ld-linux-aarch64.so.1:ro -v/lib/aarch64-linux-gnu:/lib/aarch64-linux-gnu:ro -v/usr/bin/FEXInterpreter:/usr/bin/FEXInterpreter:ro -v/usr/bin/FEXLoader:/usr/bin/FEXLoader:ro -v/usr/bin/FEXServer:/usr/bin/FEXServer:ro ubuntu:22.04 bash
root@f75a465fa85d:/# uname -a
Linux f75a465fa85d 5.19.17 #FEX-2409 SMP Sep  5 2024 23:55:18 x86_64 x86_64 x86_64 GNU/Linux
root@f75a465fa85d:/#
exit
$ docker run --rm -it --platform linux/amd64 -v/lib/ld-linux-aarch64.so.1:/lib/ld-linux-aarch64.so.1:ro -v/lib/aarch64-linux-gnu:/lib/aarch64-linux-gnu:ro -v/usr/bin/FEXInterpreter:/usr/bin/FEXInterpreter:ro -v/usr/bin/FEXLoader:/usr/bin/FEXLoader:ro -v/usr/bin/FEXServer:/usr/bin/FEXServer:ro ubuntu:24.04 bash
root@6fe2c5f4e9a5:/# uname -a
Linux 6fe2c5f4e9a5 5.19.17 #FEX-2409 SMP Sep  5 2024 23:55:18 x86_64 x86_64 x86_64 GNU/Linux
root@6fe2c5f4e9a5:/#
exit
$ docker run --rm -it --platform linux/amd64 -v/lib/ld-linux-aarch64.so.1:/lib/ld-linux-aarch64.so.1:ro -v/lib/aarch64-linux-gnu:/lib/aarch64-linux-gnu:ro -v/usr/bin/FEXInterpreter:/usr/bin/FEXInterpreter:ro -v/usr/bin/FEXLoader:/usr/bin/FEXLoader:ro -v/usr/bin/FEXServer:/usr/bin/FEXServer:ro ubuntu:24.10 bash
root@6b571f734d99:/# uname -a
Linux 6b571f734d99 5.19.17 #FEX-2409 SMP Sep  5 2024 23:55:18 x86_64 x86_64 x86_64 GNU/Linux
root@6b571f734d99:/#

Run this on your host system to see where libstdc++ is installed and make sure to update the mounts to include it:

$ ldd `which FEXLoader`
	linux-vdso.so.1 (0x0000ffffb37a8000)
	libstdc++.so.6 => /lib/aarch64-linux-gnu/libstdc++.so.6 (0x0000ffffb2c40000)
	libm.so.6 => /lib/aarch64-linux-gnu/libm.so.6 (0x0000ffffb2ba0000)
	libgcc_s.so.1 => /lib/aarch64-linux-gnu/libgcc_s.so.1 (0x0000ffffb2b70000)
	libc.so.6 => /lib/aarch64-linux-gnu/libc.so.6 (0x0000ffffb29c0000)
	/lib/ld-linux-aarch64.so.1 (0x0000ffffb376f000)

[Radiicall]

Yes it would seem so, my /lib/aarch64-linux-gnu is almost empty, it has one library in it and i think its one generated by FEX. Dont have the laptop handy to check right now, ill see if i can get this working when i get home.

My host OS is Gentoo Linux which has some different library paths from ubuntu/debian