nixos/fontsdir: fix cross

[RossComputerGuy]

Things done

Fixes cross which @jmbaur tried fixing but it's a problem again.

/build/.attr-0l2nkwhif96f51f4amnlf414lhl4rv9vh8iffyp431v6s28gsr90: line 7: /nix/store/dibi6jg43m0aalml2d76lb8f5i0y67mk-mkfontscale-riscv64-unknown-linux-gnu-1.2.3/bin/mkfontscale: cannot execute binary file: Exec format error

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[jmbaur]

I don't see how this is possible. I've tried to reproduce this issue where you've got an aarch64-linux buildPlatform and a riscv64-linux hostPlatform below:

let
  someRevOnMaster = "742e83951eefc0a0a74dd95a6523300dacfb4238";
  inherit
    (import (builtins.getFlake "github:nixos/nixpkgs/${someRevOnMaster}") {
      system = "aarch64-linux";
    })
    pkgsCross
    ;
in
builtins.head (
  builtins.filter (drv: drv.name == "X11-fonts")
    (pkgsCross.riscv64.nixos {
      fonts.fontDir.enable = true;
      boot.isContainer = true;
    }).config.environment.systemPackages
)

This results in the following:

$ nix eval --impure --file /tmp/test.nix
evaluation warning: system.stateVersion is not set, defaulting to 25.05. Read why this matters on https://nixos.org/manual/nixos/stable/options.html#opt-system.sta
teVersion.
«derivation /nix/store/0gp81b50wg2bf2dbqswkbhvy21i8x552-X11-fonts.drv»

And that drv has the following properties

{
  "/nix/store/0gp81b50wg2bf2dbqswkbhvy21i8x552-X11-fonts.drv": {
    "args": [
      "-e",
      "/nix/store/v6x3cs394jgqfbi0a42pam708flxaphh-default-builder.sh"
    ],
    "builder": "/nix/store/rm5cm7wk2a6y17gz52ymh39d5fzai2lv-bash-5.2p37/bin/bash",
    "env": {
      "__structuredAttrs": "",
      "buildCommand": "mkdir -p \"$out/share/X11/fonts\"\nfont_regexp='.*\\.\\(ttf\\|ttc\\|otb\\|otf\\|pcf\\|pfa\\|pfb\\|bdf\\)\\(\\.gz\\)?'\nfind  -regex \"$font_
regexp\" \\\n  -exec ln -sf -t \"$out/share/X11/fonts\" '{}' \\;\ncd \"$out/share/X11/fonts\"\n\nmkfontscale\nmkfontdir\ncat $(find /nix/store/vji0ax6kvdm8sxbf7b8m
m1rbwj2ns271-font-alias-riscv64-unknown-linux-gnu-1.0.5/ -name fonts.alias) >fonts.alias\n",
      "buildInputs": "",
      "builder": "/nix/store/rm5cm7wk2a6y17gz52ymh39d5fzai2lv-bash-5.2p37/bin/bash",
      "cmakeFlags": "-DCMAKE_SYSTEM_NAME=Linux -DCMAKE_SYSTEM_PROCESSOR=riscv64 -DCMAKE_HOST_SYSTEM_NAME=Linux -DCMAKE_HOST_SYSTEM_PROCESSOR=aarch64",
      "configureFlags": "--build=aarch64-unknown-linux-gnu --host=riscv64-unknown-linux-gnu",
      "depsBuildBuild": "",
      "depsBuildBuildPropagated": "",
      "depsBuildTarget": "",
      "depsBuildTargetPropagated": "",
      "depsHostHost": "",
      "depsHostHostPropagated": "",
      "depsTargetTarget": "",
      "depsTargetTargetPropagated": "",
      "doCheck": "",
      "doInstallCheck": "",
      "enableParallelBuilding": "1",
      "enableParallelChecking": "1",
      "enableParallelInstalling": "1",
      "mesonFlags": "--cross-file=/nix/store/75gpq48zk7xppjl5hpxrwrqkv68hpwd5-cross-file.conf",
      "name": "X11-fonts",
      "nativeBuildInputs": "/nix/store/fl5mjwwd1ibphb011kmwqsl697n2abhr-gzip-1.13 /nix/store/qzwh2ml21iw67ln2qr2l9r17a2jmh6a8-mkfontscale-1.2.3 /nix/store/qzwh2ml2
1iw67ln2qr2l9r17a2jmh6a8-mkfontscale-1.2.3",
      "out": "/nix/store/dlrbwcc2i14a2c8yhlylxwnw268ss6pf-X11-fonts",
      "outputs": "out",
      "passAsFile": "buildCommand",
      "patches": "",
      "preferLocalBuild": "1",
      "propagatedBuildInputs": "",
      "propagatedNativeBuildInputs": "",
      "stdenv": "/nix/store/1vf838bcfr4hdi1pvy0wvhsm16gl8y98-stdenv-linux",
      "strictDeps": "1",
      "system": "aarch64-linux"
    },
    "inputDrvs": {
      "/nix/store/1fyz1cf9m2yvxjyq3gx4zqnrmxl9i7lp-font-alias-riscv64-unknown-linux-gnu-1.0.5.drv": {
        "dynamicOutputs": {},
        "outputs": [
          "out"
        ]
      },
      "/nix/store/9g3kgj711gg4pvfnl5aad1rghzw81sr8-gzip-1.13.drv": {
        "dynamicOutputs": {},
        "outputs": [
          "out"
        ]
      },
      "/nix/store/cggy6p43sd1qcil8h56cp3gxdx3q7dy3-mkfontscale-1.2.3.drv": {
        "dynamicOutputs": {},
        "outputs": [
          "out"
        ]
      },
      "/nix/store/dmvym833yfmarj3ybjknd50h6wq8vs26-stdenv-linux.drv": {
        "dynamicOutputs": {},
        "outputs": [
          "out"
        ]
      },
      "/nix/store/lczmm84pj8qgp3kpkwrg1lqy0bji53gh-bash-5.2p37.drv": {
        "dynamicOutputs": {},
        "outputs": [
          "out"
        ]
      }
    },
    "inputSrcs": [
      "/nix/store/75gpq48zk7xppjl5hpxrwrqkv68hpwd5-cross-file.conf",
      "/nix/store/v6x3cs394jgqfbi0a42pam708flxaphh-default-builder.sh"
    ],
    "name": "X11-fonts",
    "outputs": {
      "out": {
        "path": "/nix/store/dlrbwcc2i14a2c8yhlylxwnw268ss6pf-X11-fonts"
      }
    },
    "system": "aarch64-linux"
  }
}

As can be seen, mkfontscale is coming from /nix/store/qzwh2ml21iw67ln2qr2l9r17a2jmh6a8-mkfontscale-1.2.3, which is not cross compiled as in your error output.

[RossComputerGuy]

That's strange, I'm just using the local and cross system config under the nixpkgs option in NixOS but I don't know how that could cause this.

[jmbaur]

That's strange, I'm just using the local and cross system config under the nixpkgs option in NixOS but I don't know how that could cause this.

Can you paste a minimal reproducer here?

callPackage is supposed to choose the package-set for us, so I wouldn't expect this extra fix to be needed.

[RossComputerGuy]

let
  nixpkgs = builtins.getFlake "github:nixos/nixpkgs/d29ab98cd4a70a387b8ceea3e930b3340d41ac5a";
in
builtins.head (
  builtins.filter (drv: drv.name == "X11-fonts")
    (import "${nixpkgs}/nixos/lib/eval-config.nix" {
      modules = [
        {
          fonts.fontDir.enable = true;
          boot.isContainer = true;
          nixpkgs.crossSystem = { system = "riscv64-linux"; };
          nixpkgs.localSystem = { system = "aarch64-linux"; };
        }
      ];
    }).config.environment.systemPackages
)

I made a reproducer based on what you had and it does produce the same error.

[RossComputerGuy]

Interesting, your reproducer works. It seems the culprit is something with passing through pkgs vs the nixpkgs options is changing the behavior.

[RossComputerGuy]

Artturin and I chased where this was going wrong, the problem is #366959 didn't get into 24.11.