Installing arm64 emulator on CentOS 7: invalid argument

[marcelstoer]

I am coming from https://github.com/docker/buildx more specifically docker/buildx#495 as well as #1929 and #1943. Just to complete my analysis I also checked tonistiigi/binfmt#92.

I am now utterly confused as to which of the three projects to create an issue with.

I cannot seem to install the arm64 emulator on a Linux CI host (works fine on my macOS of course). None of the hints in the other issues fixed this so far.

[admin@t8tstjnode10 binfmt_misc]$ docker buildx ls
NAME/NODE               DRIVER/ENDPOINT             STATUS  PLATFORMS
intelligent_driscoll *  docker-container                    
  intelligent_driscoll0 unix:///var/run/docker.sock running linux/amd64, linux/amd64/v2, linux/386
default                 docker                              
  default               default                     running linux/amd64, linux/386
[admin@t8tstjnode10 binfmt_misc]$  docker run --privileged --rm tonistiigi/binfmt --install arm64
installing: arm64 cannot register "/usr/bin/qemu-aarch64" to /proc/sys/fs/binfmt_misc/register: write /proc/sys/fs/binfmt_misc/register: invalid argument
{
  "supported": [
    "linux/amd64",
    "linux/386"
  ],
  "emulators": null
}

As for my environment:

[admin@t8tstjnode10 binfmt_misc]$ docker --version
Docker version 20.10.17, build 100c701
[admin@t8tstjnode10 binfmt_misc]$ docker run --privileged --rm tonistiigi/binfmt --version
binfmt/1aa2eba qemu/v6.2.0 go/1.17.8
[admin@t8tstjnode10 binfmt_misc]$ uname -srm
Linux 3.10.0-1160.66.1.el7.x86_64 x86_64
[admin@t8tstjnode10 binfmt_misc]$ cat /etc/os-release
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"

CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"
[admin@t8tstjnode10 ~]$ cat /etc/centos-release
CentOS Linux release 7.9.2009 (Core)

Trying to reset the qemu-user-static yields the same invalid argument response:

[admin@t8tstjnode10 binfmt_misc]$ docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
Setting /usr/bin/qemu-alpha-static as binfmt interpreter for alpha
sh: write error: Invalid argument
Setting /usr/bin/qemu-arm-static as binfmt interpreter for arm
...

[marcelstoer]

Oh, according to https://medium.com/@artur.klauser/building-multi-architecture-docker-images-with-buildx-27d80f7e2408 kernel version >=4.8 is required for multi-arch builds.

Also hidden in some sentence in the 6th paragraph at https://docs.docker.com/buildx/working-with-buildx/#build-multi-platform-images.

[marcelstoer]

And it looks like multiarch/qemu-user-static#100 has relevant information, too. <goes-digging>...

[marcelstoer]

Conclusion: upgrade to CentOS 8.