add systemd service files

init/udev-retry.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=re-trigger failed events after filesystems are available
+After=local-fs.target
+
+[Service]
+Type=finish
+ValidNoProcess=yes
+ExecStart=/sbin/udevadm trigger --type=failed
+
+[Install]
+WantedBy=sysinit.target
+Also=udev.service
+Also=udev-settle.service

init/udev-settle.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=wait until full initialization
+After=udev.service
+
+[Service]
+Type=finish
+ValidNoProcess=yes
+ExecStart=/sbin/udevadm settle
+
+[Install]
+WantedBy=sysinit.target
+Also=udev.service
+Also=udev-retry.service

init/udev.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=/dev and kernel device manager
+Before=sysinit.target
+
+[Service]
+Type=notify
+ExecStart=/sbin/udevd
+ExecStartPost=/sbin/udevadm trigger --type=subsystems --action=add
+ExecStartPost=/sbin/udevadm trigger --type=devices --action=add
+
+[Install]
+WantedBy=sysinit.target
+Also=udev-settle.service
+Also=udev-retry.service
+