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2013-09-27-initramfs-required
Title Separate /usr on Linux requires initramfs
Author William Hubbs williamh@gentoo.org
Posted 2013-09-27
Revision 1

Linux systems which have / and /usr on separate file systems but do not
use an initramfs will not be supported starting on 01-Nov-2013.

If you have / and /usr on separate file systems and you are not
currently using an initramfs, you must set one up before this date.
Otherwise, at some point on or after this date, upgrading packages
will make your system unbootable.

For more information on setting up an initramfs, see this URL:

https://wiki.gentoo.org/wiki/Initramfs/HOWTO

Due to many upstream changes, properly supporting Linux systems that
have /usr missing at boot time has become increasingly difficult.
Despite all our efforts, it already breaks in some exotic
configurations, and this trend is likely to grow worse.

For more information on the upstream changes and why using an initramfs
is the cleanest route forward, see the following URLs:

http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken
https://blog.flameeyes.eu/2013/01/the-boot-process