nixos/nix-ld: Support 32-bit portability

flake.nix

@@ -44,6 +44,22 @@
           );
       });
 
+      systems.x86_64-linux.test =
+        (self.lib.nixosSystem {
+          system = "x86_64-linux";
+          modules = [
+            ({
+              boot.loader.grub.enable = false;
+              fileSystems."/".device = "nodev";
+              # See https://search.nixos.org/options?show=system.stateVersion&query=stateversion
+              system.stateVersion = lib.versions.majorMinor lib.version; # DON'T do this in real configs!
+
+              programs.nix-ld.systems.x86_64-linux = { };
+            })
+          ];
+        });
+      packages.x86_64-linux.test = self.systems.x86_64-linux.test.config.system.build.toplevel;
+
       checks = forAllSystems (system: {
         tarball = jobs.${system}.tarball;
         # Exclude power64 due to "libressl is not available on the requested hostPlatform" with hostPlatform being power64

nixos/doc/manual/release-notes/rl-2205.section.md

@@ -125,7 +125,7 @@ In addition to numerous new and upgraded packages, this release has the followin
 
 - [nifi](https://nifi.apache.org), an easy to use, powerful, and reliable system to process and distribute data. Available as [services.nifi](#opt-services.nifi.enable).
 
-- [nix-ld](https://github.com/Mic92/nix-ld), Run unpatched dynamic binaries on NixOS. Available as [programs.nix-ld](#opt-programs.nix-ld.enable).
+- [nix-ld](https://github.com/Mic92/nix-ld), Run unpatched dynamic binaries on NixOS. Available as `programs.nix-ld`.
 
 - [NNCP](http://www.nncpgo.org), NNCP (Node to Node copy) utilities and configuration, Available as [programs.nncp](#opt-programs.nncp.enable).
 

nixos/modules/programs/nix-ld.nix

@@ -1,61 +1,109 @@
 { pkgs, lib, config, ... }:
 let
-  cfg = config.programs.nix-ld;
+  inherit (lib)
+    literalExpression
+    mapAttrsToList
+    mergeAttrsList
+    mkEnableOption
+    mkMerge
+    mkOption
+    mkPackageOption
+    types;
 
-  nix-ld-libraries = pkgs.buildEnv {
+  cfg = config.programs.nix-ld.systems;
+
+  share-path = system: "share/nix-ld-${system}";
+
+  nix-ld-libraries = system: cfg: cfg.pkgs.buildEnv {
     name = "ld-library-path";
     pathsToLink = [ "/lib" ];
     paths = map lib.getLib cfg.libraries;
     # TODO make glibc here configurable?
     postBuild = ''
-      ln -s ${pkgs.stdenv.cc.bintools.dynamicLinker} $out/share/nix-ld/lib/ld.so
+      ln -s ${cfg.pkgs.stdenv.cc.bintools.dynamicLinker} $out/${share-path system}/lib/ld.so
     '';
-    extraPrefix = "/share/nix-ld";
+    extraPrefix = "/${share-path system}";
     ignoreCollisions = true;
   };
 in
 {
   meta.maintainers = [ lib.maintainers.mic92 ];
-  options.programs.nix-ld = {
-    enable = lib.mkEnableOption ''nix-ld, Documentation: <https://github.com/Mic92/nix-ld>'';
-    package = lib.mkPackageOption pkgs "nix-ld" { };
-    libraries = lib.mkOption {
-      type = lib.types.listOf lib.types.package;
-      description = "Libraries that automatically become available to all programs. The default set includes common libraries.";
-      default = [ ];
-      defaultText = lib.literalExpression "baseLibraries derived from systemd and nix dependencies.";
-    };
-  };
 
-  config = lib.mkIf config.programs.nix-ld.enable {
-    environment.ldso = "${cfg.package}/libexec/nix-ld";
-
-    environment.systemPackages = [ nix-ld-libraries ];
-
-    environment.pathsToLink = [ "/share/nix-ld" ];
-
-    environment.variables = {
-      NIX_LD = "/run/current-system/sw/share/nix-ld/lib/ld.so";
-      NIX_LD_LIBRARY_PATH = "/run/current-system/sw/share/nix-ld/lib";
-    };
-
-    # We currently take all libraries from systemd and nix as the default.
-    # Is there a better list?
-    programs.nix-ld.libraries = with pkgs; [
-      zlib
-      zstd
-      stdenv.cc.cc
-      curl
-      openssl
-      attr
-      libssh
-      bzip2
-      libxml2
-      acl
-      libsodium
-      util-linux
-      xz
-      systemd
-    ];
+  options.programs.nix-ld.systems = mkOption {
+    default = { };
+    description = ''
+      Configure nix-ld for the given system.
+    '';
+    type = types.attrsOf (types.submodule {
+      options = {
+        enable = mkEnableOption "nix-ld for the given system";
+        package = mkPackageOption pkgs "nix-ld" { };
+
+        pkgs = mkOption {
+          type = types.pkgs;
+          default = pkgs;
+          defaultText = "pkgs";
+          description = "Package set to use";
+        };
+
+        ldso = mkOption {
+          type = types.str;
+          description = ''
+            Which runtime loader to override, either `ldso` or `ldso32`, see
+            `environment.ldso` and `environment.ldso32`.
+          '';
+          default = "ldso";
+        };
+
+        libraries = mkOption {
+          type = types.listOf types.package;
+          description = "Libraries that automatically become available to all programs. The default set includes common libraries.";
+          default = [ ];
+          defaultText = literalExpression "baseLibraries derived from systemd and nix dependencies.";
+        };
+      };
+    });
   };
+
+  config =
+    let
+      recursive =
+        # mkMerge
+        mergeAttrsList
+          (mapAttrsToList
+            (system: cfg: {
+              environment.${cfg.ldso} = "${cfg.package}/libexec/nix-ld";
+
+              environment.systemPackages = [ (nix-ld-libraries system cfg) ];
+
+              environment.pathsToLink = [ "/${share-path system}" ];
+
+              environment.variables = {
+                "NIX_LD_${builtins.replaceStrings ["-"] ["_"] system}" = "/run/current-system/sw/${share-path system}/lib/ld.so";
+                "NIX_LD_LIBRARY_PATH_${builtins.replaceStrings ["-"] ["_"] system}" = "/run/current-system/sw/${share-path system}/lib";
+              };
+
+              # We currently take all libraries from systemd and nix as the default.
+              # Is there a better list?
+              programs.nix-ld.systems.${system}.libraries = with cfg.pkgs; [
+                zlib
+                zstd
+                stdenv.cc.cc
+                curl
+                openssl
+                attr
+                libssh
+                bzip2
+                libxml2
+                acl
+                libsodium
+                util-linux
+                xz
+                systemd
+              ];
+            })
+            cfg);
+    in
+    # recursive;
+    { environment.etc.foo.text = builtins.toJSON recursive; };
 }