trim down the qemu kernel config

just retain the options we need to pass the tests

modules/base.nix

@@ -56,10 +56,13 @@ in {
 
         MODULES = "y";
 
-        # not going far without Unix domain sockets
+        # basic networking protocols
+        NET = "y";
         UNIX = "y";
         INET = "y";
         IPV6 = "y";
+        PACKET = "y";           # for ppp, tcpdump ...
+        SYSVIPC= "y";
 
         # s6-linux-init mounts this on /dev
         DEVTMPFS = "y";

modules/wlan.nix

@@ -0,0 +1,20 @@
+{ lib, pkgs, config, ...}:
+let
+  inherit (lib) mkEnableOption mkOption types isDerivation hasAttr ;
+  inherit (pkgs.pseudofile) dir symlink;
+  inherit (pkgs) busybox;
+
+in {
+  config = {
+    kernel = rec {
+      config = {
+        CFG80211= "y";
+        MAC80211= "y";
+        MAC80211_MESH= "y";
+        RFKILL= "y";
+        WLAN = "y";
+      };
+      checkedConfig = config;
+    };
+  };
+}