Enable kmod-static-nodes.service

This creates static device nodes such as /dev/fuse or
/dev/snd/seq. The kernel modules for these devices will be loaded on
demand when the device node is opened.

nixos/modules/system/boot/kernel.nix

@@ -147,6 +147,12 @@ in
 
   config = mkIf (!config.boot.isContainer) {
 
+    systemd.services.kmod-static-nodes =
+      { wantedBy = [ "sysinit.target" ];
+        baseUnit = "${config.systemd.package}/example/systemd/system/kmod-static-nodes.service";
+        environment.MODULE_DIR = "/run/booted-system/kernel-modules/lib/modules";
+      };
+
     system.build = { inherit kernel; };
 
     system.modulesTree = [ kernel ] ++ config.boot.extraModulePackages;

pkgs/os-specific/linux/systemd/fixes.patch

@@ -181,6 +181,18 @@ index aa853b8..8bcc647 100644
  Type=idle
  Restart=always
  RestartSec=0
+diff --git a/units/kmod-static-nodes.service.in b/units/kmod-static-nodes.service.in
+index 368f980..d0c1bd2 100644
+--- a/units/kmod-static-nodes.service.in
++++ b/units/kmod-static-nodes.service.in
+@@ -10,7 +10,6 @@ Description=Create list of required static device nodes for the current kernel
+ DefaultDependencies=no
+ Before=sysinit.target systemd-tmpfiles-setup-dev.service
+ ConditionCapability=CAP_MKNOD
+-ConditionPathExists=/lib/modules/%v/modules.devname
+ 
+ [Service]
+ Type=oneshot
 diff --git a/units/local-fs.target b/units/local-fs.target
 index ae3cedc..0e36840 100644
 --- a/units/local-fs.target