-The udev runtime data moved from /dev/.udev/ to /dev/.run/udev/.
-On new systems the tmpfs mountpoint /var/run/ will have an
-"early-boot alias" /dev/.run/ where udev and a couple of other
-early-boot tools will put their runtime data.
-On systems with LVM used, packagers must make sure, that the
-initramfs creates the /dev/.run/ mountpoint for udev to store
-the data, so that the real root will not overmount it, which
-would make it invisible.
+The udev runtime data moved from /dev/.udev/ to /run/udev/. The
+/run mountpoint is supposed to be a tmpfs mounted during early boot,
+available and writable to for all tools at any time during bootup,
+it replaces /var/run/, which should become a symlink some day.
+
+If /run does not exist, or is not writable, udev will fall back using
+/dev/.udev/.
+
+On systemd systems with initramfs and LVM used, packagers must
+make sure, that the systemd and initramfs versions match. The initramfs
+needs to create the /run/ mountpoint for udev to store the data, and
+mount this tmpfs to /run in the rootfs, so the that the udev database
+is preserved for the udev version started in the rootfs.