Running nixos-rebuild across platforms

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I’m using a Flake to define a NixOS system for a Raspberry Pi. By setting:

  nixpkgs.buildPlatform = "x86_64-linux";
  nixpkgs.hostPlatform = "aarch64-linux";

I’m able to cross-compile NixOS on my x86 box, i.e. I can generate an SD card image like this:

nix build .#nixosConfigurations.sandy.config.system.build.sdImage

Which boots up fine on the Pi.

Now the issue is that nixos-rebuild seems to want to run aarch64 binaries on my build host:

❯❯  nixos-rebuild switch --flake .#sandy --target-host 192.168.0.81 --use-remote-sudo
/nix/store/svk2dgsb1j87z6sqb3c5257d6n0l4vf8-nixos-rebuild/bin/nixos-rebuild: line 443: /nix/store/7hwrcf22m39i3mx7qxwbjjidnz2in777-coreutils-aarch64-unknown-linux-gnu-9.6/bin/mktemp: cannot execute binary file: Exec format error

I have a feeling there’s a way to work around this by just getting my x86 host to support running Arm binaries with binfmt_misc hackery, but I don’t really wanna do that if I can avoid it. (My x86 host system is not NixOS, plus this is inefficient and generally unsatisfying).

Also, I tried setting --build-host to point to the Pi as well, this is also not really a solution but I wanted to see what would happen. Turns out I still got the Exec format error which is a bit surprising…

Does anyone know what I’m missing here?

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I run into a similar error with with my Raspberry
.../bin/bash: Exec format error
with a config that built fine 2 weeks ago

More similar problems multiple packages: crash on aarch64-linux · Issue #399133 · NixOS/nixpkgs · GitHub

3

Left a comment on the issue multiple packages: crash on aarch64-linux · Issue #399133 · NixOS/nixpkgs · GitHub.

I’ve encountered the same error on an Intel laptop, might be due to some systemd hardening options present in the nixos modules I’ve used - grafana and postgresql are pretty popular, so they should have hardening options enabled. I’ve created my own module for qbittorrent-nox by blindly copying some of the options from other services. Initially it worked fine, but then suddenly started crashing with the “exec error”.

Unfortunately my pi ended up dying due to a broken sd card, so I didn’t get the opportunity to investigate this further.

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