I'd like to remove the following deprecated functionality from initscripts/udev.
If you have several networking devices or cd-rom's they might get their names swapped around on reboot. This is of course annoying.
The old solution:
udev ships with a rule file to automatically generate a persistent rule file in /etc every time it sees a new network device or cd-rom.
/etc might not always be writable (in particular it is not during early boot when devices are typically probed), for this we have a workaround/hack in initscripts that will copy temporarily stored rule files to /etc when /etc becomes available.
these days things like usb modems pretend to be cdroms so one might have potentially a lot of nonsense rules generated
the functionality is basically deprecated upstream, i.e., they intend to rip it out as soon as someone has written a nice tool to replace it. For all intents and purposes it is dead.
The correct solution:
The user should not enable the auto generation rules, but rather create his/her own rules in the cases where they really want it. This is the same amount of manual intervention as enabling the rules, with none of the drawback. The correct procedure is excellently described here: https://wiki.archlinux.org/index.php/Udev#Mixed_Up_Devices.2C_Sound.2FNetwork_Cards_Changing_Order_Each_Boot (the method referred to as the "udev-sanctioned" one).
The situation in Arch:
The auto generation rules are shipped, but patched to be disabled by default, the needed support is still in initscripts.
We announce the deprecation and point users to the correct solution (maybe we fix up the relevant wiki pages a bit). After a not too long time we stop shipping the autogeneration rules, i.e., we pass
to configure in the udev package, and remove the support from initscripts.
What this will mean for the end user:
On an existing system where the rules are enabled and no new devices are added: nothing.
On an existing system where the rules are enabled and a new device is added: the new devices will not get an auto generated persistent rule and an error will be logged.