Eudev

eudev is a fork of systemd-udev with the goal of obtaining better compatibility with existing software such as OpenRC and Upstart, older kernels, various toolchains and anything else required by users and various distributions.

Migrate from udev to eudev
This section should be completed. Meanwhile, check these forum threads:

Moving from udev 216 to eudev 1.10-r2 (March 2015) is straigthforward : http://forums.gentoo.org/viewtopic-p-7712064.html#7712064

emerge --ask eudev

The network interface naming convention is not the same so you'll need to re-link /etc/init.d from net.lo to net.eth0 or wathever networkin interface you use and add net.eth0 to the default runlevel

Moving from udev (171-r10) to eudev (1.2-r1) http://forums.gentoo.org/viewtopic-t-966786-start-0.html

Broken system switching from udev to eudev http://forums.gentoo.org/viewtopic-t-1011456.html