gentoo-locomotion/sys-fs/udev/files/80-net-setup-link.rules

#
# Udev 197 and above has implemented predictable network interface names
# for hardware network interfaces. This new scheme does not affect
# stacked network interfaces such as bonds, bridges or vlans.
#
# This file is here to prevent your interfaces from being renamed automatically,
# because the new names will be drastically different from the eth*, wlan*, etc
# names you are used to working with.
#
# To activate this function, copy 80-net-setup-link.rules from /lib/udev/rules.d/
# to /etc/udev/rules.d/
# Deleting the file from /etc/udev/rules.d/ works too but when you re-emerge
# the current stable udev it will restore this dummy file there if it isn't there
# already!
#
# If you want to deactivate this function, install a udev rules file as
# /etc/udev/rules.d/80-net-setup-link.rules then reboot your system.
#
# This functionality has not been tested with gentoo. In fact, we are aware that
# things will break if you activate it.
#
# If you are not comfortable testing this, leave this file as is. We will
# publish a news item when you can migrate.
#
# If you do want to activate and help us come up with a migration plan, feel
# free to do so and report bugs.
# Your bugs should block the following tracker:
# https://bugs.gentoo.org/454224
#
# Before you activate this function, it is important that you fully understand
# the following documentation:
#
# http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames
#
# Also, be aware that you can get the attributes of your network interface that
# would be used to name the interface in the new scheme by doing the following
# with this version of udev running:
#
# udevadm test-builtin net_id /sys/class/net/ifname 2> /dev/null
#
# for example, on my system, I can find that eth0's new name would be enp1s5.
#