Quoting Didier Kryn (kryn@???):

> mdev is fine for a server. It is lacking a few features w/r udev:
>
> 1) It doesn't build /dev/disk/[by-id | by-label | by-partuuid |
> by-path | by-uuid]

These are important things to note, for anyone who actually likes and
uses those features. (So, thanks.)

As it happens, I don't. Persistent device naming is a neat trick, though,
and has its uses and necessities.
https://wiki.archlinux.org/index.php/persistent_block_device_naming
explains:

If your machine has more than one SATA, SCSI or IDE disk controller,
the order in which their corresponding device nodes are added is
arbitrary. This may result in device names like /dev/sda and /dev/sdb
switching around on each boot, culminating in an unbootable system,
kernel panic, or a block device disappearing. Persistent naming solves
these issues.

I've never had a Linux system where that is even potentially an issue,
and don't expect ever to. However, it's a real solution to a problem
some people reportedly do have. (My main suggestion to people having
device-naming problems because they used multiple different-driver SATA
controllers, or multiple USB cards, or muliple SAS cards, would be
'Well, Don't Do That, Then.'[1])


> 2) It doesn't come with a library for applications to retrieve
> information about the devices. This affects primarily the X11
> configuration, which means you will need to provide some Xorg.conf
> file, like in the old times.

Quite so. xorg.conf is _still_ dead-simple to programmatically generate,
though. Just do 'Xorg -configure'. Done. Then 'cp xorg.conf.new
/etc/X11/xorg.conf' . Edit to suit.


> I don't know if its affects also other subsystems, like audio.

Neale Pickett wrote on
https://woozle.org/neale/papers/runit-as-init.html (where he used mdev
with runit in Arch Linux:

Stuff that never quite worked

I had to set up a dmix device for ALSA, which usually worked, but
sometimes things would get an exclusive lock on the sound hardware,
which prevented other things from making sound.

I could never get Chrome to get sound from the USB webcam I had to use
at work. It would list it as a microphone source, and occasionally if I
kept selecting every mic source over and over, it would start working.
But it was never consistent, and I was never able to figure out why not.

I never figured out how to get X11 to use evdev devices.

[1] http://www.catb.org/jargon/html/D/Don-t-do-that-then-.html