pkgs.writeErofsLayers,profiles/ch-runner: MVE

$ nix-build -A examples.dummy.config.debug.closure.erofs.list | xargs
cat | xargs du -h
749M    /nix/store/bzfv5x6lycq6hzhjv6d6vlk1q8fdg9di-base0.erofs
24M     /nix/store/hp41jfq36y0mmjrzqilyh3jfsvqic3kb-nixos.erofs

$ nix run -f . examples.dummy.config.uvms.cloud-hypervisor.runner
...
<<< Welcome to NixOS 25.11pre-git (x86_64) - ttyS0 >>>

nixos login:

The definition of the `pkgs` fixpoint was moved to pkgs/default.nix.
For that, dirToAttrs was moved to lib/, imported ad hoc

lib/dirToAttrs.nix

@@ -0,0 +1,20 @@
+{ lib }:
+root: patterns: f:
+lib.listToAttrs (
+  lib.concatMap (
+    dirent:
+    let
+      fname = dirent.name;
+      typ = dirent.value;
+      fpath = root + "/${fname}";
+      doMatch =
+        pat:
+        let
+          match = pat fpath fname typ;
+          value = f match fpath typ;
+        in
+        if match == null then [ ] else [ (lib.nameValuePair match value) ];
+    in
+    (lib.take 1 (lib.concatMap (doMatch) patterns))
+  ) (lib.attrsToList (builtins.readDir root))
+)

lib/mkIfMicrovmGuest.nix

@@ -0,0 +1,7 @@
+{
+  lib,
+  options,
+  config,
+}:
+def:
+lib.optionalAttrs (options ? "microvm"."guest"."enable") (lib.mkIf config.microvm.guest.enable def)