think

we only currently support huawei e3372/cdc ncm so let's make that
explicit in the naming

THOUGHTS.txt

@@ -5392,3 +5392,11 @@ we also need to expunge all mention of kexec
 
 and mention the upgrade choices in the Configuration section so
 people don't build an unupgradable image and only find out later
+
+Fri Jul 12 21:20:00 BST 2024
+
+generalising the failover example:
+
+- usb stick may or may not need a modeswitch
+- may need a different chat script
+- usb ids

doc/admin.rst

@@ -5,9 +5,12 @@ Services on a running system
 ****************************
 
 Liminix services are built on s6-rc, which is itself layered on s6.
-See configuration / services node for how to specify them.
-
-
+Services are defined at build time in your configuration (see
+:ref:`configuration-services` for information) and can't be added
+to/changed at runtime, but to monitor
+events or diagnose problems you may need to inspect them on the
+running system. Here are some of the most commonly used s6,-rc
+commands:
 
 .. list-table:: Service management quick reference
    :widths: 55 45

doc/configuration.rst

@@ -86,6 +86,7 @@ domains, or you want to run two SSH daemons on different ports.
 	 don't use the NixOS modules themselves, because the
 	 underlying system is not similar enough for them to work.
 
+.. _configuration-services:
 
 Services
 ********

examples/l2tp.nix

@@ -39,7 +39,7 @@ in rec {
   };
 
   imports = [
-    ../modules/cdc-ncm
+    ../modules/wwan
     ../modules/network
     ../modules/vlan
     ../modules/ssh
@@ -50,7 +50,7 @@ in rec {
   ];
   hostname = "thing";
 
-  services.wwan = svc.wwan.build {
+  services.wwan = svc.wwan.huawei-e3372.build {
     apn = "data.uk";
     username = "user";
     password = "one2one";

modules/cdc-ncm/default.nix

@@ -1,31 +0,0 @@
-{ config, pkgs, lib, ... }:
-let
-  inherit (pkgs) liminix;
-  inherit (lib) mkOption types;
-in {
-  imports = [
-    ../service-trigger
-  ];
-
-  options = {
-    system.service.wwan = mkOption {
-      type = liminix.lib.types.serviceDefn;
-    };
-  };
-  config = {
-    kernel.config = {
-      USB_NET_HUAWEI_CDC_NCM = "y";
-      USB_USBNET = "y";
-      USB_SERIAL = "y";
-      USB_SERIAL_OPTION = "y";
-    };
-
-    # https://www.0xf8.org/2017/01/flashing-a-huawei-e3372h-4g-lte-stick-from-hilink-to-stick-mode/
-    system.service.wwan = config.system.callService ./wwan.nix {
-      apn = mkOption { type = types.str; };
-      username = mkOption { type = types.str; };
-      password = mkOption { type = types.str; };
-      authType = mkOption { type = types.enum [ "pap" "chap" ]; };
-    };
-  };
-}

modules/wwan/default.nix

@@ -0,0 +1,45 @@
+{ config, pkgs, lib, ... }:
+let
+  inherit (pkgs) liminix;
+  inherit (lib) mkOption types;
+  huawei-cdc-ncm = pkgs.kmodloader.override {
+    targets = ["huawei_cdc_ncm"];
+    inherit (config.system.outputs) kernel;
+  };
+in {
+  imports = [
+    ../service-trigger
+  ];
+
+  options = {
+    system.service.wwan.huawei-e3372 = mkOption {
+      type = liminix.lib.types.serviceDefn;
+    };
+  };
+  config = {
+    kernel.config = {
+      USB_NET_HUAWEI_CDC_NCM = "m";
+      USB_USBNET = "y";
+      USB_SERIAL = "y";
+      USB_SERIAL_OPTION = "y";
+    };
+
+    # https://www.0xf8.org/2017/01/flashing-a-huawei-e3372h-4g-lte-stick-from-hilink-to-stick-mode/
+    system.service.wwan.huawei-e3372 =
+      let svc = config.system.callService ./huawei-e3372.nix {
+            apn = mkOption { type = types.str; };
+            username = mkOption { type = types.str; };
+            password = mkOption { type = types.str; };
+            authType = mkOption { type = types.enum [ "pap" "chap" ]; };
+          };
+      in
+        svc // {
+          build = args :
+            let args' = args // {
+                  dependencies = (args.dependencies or []) ++
+                                 [huawei-cdc-ncm];
+                };
+            in svc.build args' ;
+        };
+  };
+}