Title: /usr merge for systemd users
Author: Mike Gilbert <floppym@gentoo.org>
Posted: 2022-12-01
Revision: 2
News-Item-Format: 2.0
Display-If-Installed: sys-apps/systemd

In the latter half of 2023, systemd will drop support for
split-usr/unmerged-usr systems [1]. All Gentoo systems running systemd
will need to be migrated to merged-usr.

Migrating to merged-usr will move all data from /bin, /sbin, and /lib
into the /usr/bin and /usr/lib directories. The directories in / are
replaced with symlinks.

To facilitate this, a new set of sub-profiles has been created, and a
script is available to perform the actual migration.

To migrate a system to merged-usr, follow this procedure:

1. Ensure your system backups are up to date.

2. Install sys-apps/merge-usr.

3. Run the merge-usr script. The --dryrun option may be used to
   check for error conditions before running the script for real.

4. Switch to a merged-usr profile.
     eg. eselect profile set default/linux/amd64/17.1/systemd/merged-usr

5. Run emerge with the --newuse or --changed-use option to rebuild
   any packages that have a "split-usr" USE flag.
     eg. emerge -uDN @world

For new installs, new "mergedusr" stage3 tarballs are being produced for
commonly used profiles.

[1] https://lists.freedesktop.org/archives/systemd-devel/2022-September/048352.html