ngc7331's Blog

nixpkgs.crossSystem = {
  config = "riscv64-unknown-linux-gnu";
  gcc.arch = "rv64gc_zfh_xtheadba_...";
  gcc.abi = "lp64d";
};

runCommand "fc-cache" {
    # ...
}
''
  # ...
  ${stdenv.hostPlatform.emulator buildPackages} ${lib.getExe' fontconfig "fc-cache"} -sv
  # ...
''

postInstall =
  ''
    # ...
  ''
  + lib.optionalString withIntrospection ''
    # We need to install 'loaders.cache' in lib/gdk-pixbuf-2.0/2.10.0/
    ${stdenv.hostPlatform.emulator buildPackages} $dev/bin/gdk-pixbuf-query-loaders --update-cache
  '';

nativeBuildInputs =
  [
    # ...
  ]
  ++ lib.optionals (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) [
    mesonEmulatorHook
  ];

mesonEmulatorHook =
  makeSetupHook
    {
      name = "mesonEmulatorHook";
      substitutions = {
        crossFile = writeText "cross-file.conf" ''
          [binaries]
          exe_wrapper = '${lib.escape [ "'" "\\" ] (stdenv.targetPlatform.emulator pkgs)}'
        '';
      };
    }
    (
      if (!stdenv.hostPlatform.canExecute stdenv.targetPlatform) then
        ../by-name/me/meson/emulator-hook.sh
      else
        throw "mesonEmulatorHook may only be added to nativeBuildInputs when the target binaries can't be executed; however you are attempting to use it in a situation where ${stdenv.hostPlatform.config} can execute ${stdenv.targetPlatform.config}. Consider only adding mesonEmulatorHook according to a conditional based canExecute in your package expression."
      );

buildCommand = ''
  # ...
  export emulator=${lib.escapeShellArg (stdenv.targetPlatform.emulator buildPackages)}
  export emulatorwrapper="$dev/bin/g-ir-scanner-qemuwrapper"
  # ...
  substituteAll "${./wrappers/g-ir-scanner-qemuwrapper.sh}" "$dev/bin/g-ir-scanner-qemuwrapper"
''

{ qemu-cpu, ... }:

self: super: {
  # override original `nixpkgs/pkgs/top-level/all-packages.nix`.mesonEmulatorHook
  # to add t-head vendor extensions to QEMU arguments.
  mesonEmulatorHook =
    super.makeSetupHook
      {
        name = "mesonEmulatorHook";
        substitutions = {
          crossFile = super.writeText "cross-file.conf" ''
            [binaries]
            exe_wrapper = ['${super.lib.escape [ "'" "\\" ] (super.stdenv.targetPlatform.emulator super.buildPackages)}', '-cpu', '${qemu-cpu}']
          '';
        };
      }
      (
        if (super.stdenv.buildPlatform != super.stdenv.targetPlatform) then
          ./emulator-hook.sh
        else
          throw "mesonEmulatorHook may only be added to nativeBuildInputs when the target binaries can't be executed; however you are attempting to use it in a situation where ${super.stdenv.hostPlatform.config} can execute ${super.stdenv.targetPlatform.config}. Consider only adding mesonEmulatorHook according to a conditional based canExecute in your package expression."
      );
}

{
  buildPackages,
  fontconfig,
  lib,
  runCommand,
  stdenv,
  qemu-cpu, # added
}:
# ...
runCommand "fc-cache"
  {
    # ...
  }
  ''
    # ...
    export QEMU_CPU=${qemu-cpu} # added
    ${stdenv.hostPlatform.emulator buildPackages} ${lib.getExe' fontconfig "fc-cache"} -sv
    # ...
  ''

{ qemu-cpu, ... }:

self: super: {
  makeFontsCache =
    if (super.stdenv.buildPlatform != super.stdenv.targetPlatform) then
      super.callPackage ./make-fonts-cache.nix {
        inherit qemu-cpu;
      }
    else
      super.makeFontsCache
    ;
}

{ qemu-cpu, ... }:

self: super: {
  gdk-pixbuf =
    if (super.stdenv.buildPlatform != super.stdenv.targetPlatform) then
      super.gdk-pixbuf.overrideAttrs (old: {
        postInstall = ''
          export QEMU_CPU=${qemu-cpu}
        '' + old.postInstall;
      })
    else
      super.gdk-pixbuf
    ;
}

{ qemu-cpu, ... }:

self: super: {
  gobject-introspection =
    if (super.stdenv.buildPlatform != super.stdenv.targetPlatform) then
      super.gobject-introspection.overrideAttrs (old: {
        buildCommand = old.buildCommand + ''
          (
            export emulator=${super.lib.escapeShellArg (super.stdenv.targetPlatform.emulator super.buildPackages)}
            export emulatorargs="-cpu ${qemu-cpu}"
            substituteAll "${./g-ir-scanner-qemuwrapper.sh}" "$dev/bin/g-ir-scanner-qemuwrapper"
            chmod +x "$dev/bin/g-ir-scanner-qemuwrapper"
          )
        '';
      })
    else
      super.gobject-introspection
    ;
}

# ...
            export emulator="${super.lib.escapeShellArg (super.stdenv.targetPlatform.emulator super.buildPackages)} -cpu ${qemu-cpu}"
# ...