default/linux/ppc64/23.0/split-usr

A profile upgrade to version 23.0 is available for your architecture.
The new 23.0 profiles enable some toolchain hardening features and 
performance enhancements by default, and standardize settings.
You can find the list of changes on the wiki tracking page [1].

Upgrade instructions

Note 1: If you have manually changed your CHOST to a value different from 
what the stages and profiles set, you may have to do that in the future too.
In that case you should know what you are doing, hopefully; please read the 
instructions with a critical eye then.

Note 2: In case you are already familiar with binary packages, you should be
able to add "--getbinpkg" to the emerge calls to speed things up.
The use of binary packages is completely optional though, and also not
as much tested as the source-based upgrade path yet.

1. Ensure your system backups are up to date. Please also update
   your system fully and depclean before proceeding.
   glibc older than 2.36 and musl older than 1.2.4 is not supported anymore.

2. If you are still using one of the long-deprecated amd64 17.0 profiles 
   (other than x32 or musl), then first complete the migration to the 
   corresponding 17.1 profile. Instructions can be found at [3].
   
3. If you are currently using systemd in a split-usr configuration, then first 
   complete the migration to the corresponding merged-usr profile of the 
   same profile version. Details on how to do this can be found in the news 
   item [4].
   If you are currently using openrc, migrate to 23.0 first, keeping your disk
   layout. If you want to move from split-usr to merged-usr, do that afterwards.

4. Run "emerge --info" and note down the value of the CHOST variable.

5. Edit /etc/portage/make.conf; if there is a line defining the CHOST variable,
   remove it. Also delete all lines defining CHOST_... variables.

6. Select the 23.0 profile corresponding to your current profile, either using
   "eselect profile" or by manually setting the profile symlink.
   Note that old profiles are by default split-usr and the 23.0 profiles by
   default merged-usr. Do NOT change directory scheme now, since this will
   mess up your system! 
   Instead, make sure that the new profile has the same property: for example, 
   OLD default/linux/amd64/17.1  
        ==>  NEW default/linux/amd64/23.0/split-usr
             (added "split-usr")
   OLD default/linux/amd64/17.1/systemd/merged-usr  
        ==>  NEW default/linux/amd64/23.0/systemd
             (removed "merged-usr")
   A detailed table of the upgrade paths can be found at [5]. Please consult it.
   In some cases (hppa, x86) the table will tell you to pick between two choices. 
   What you need should be obvious from your *old* CHOST value (from step 4).

7. Delete the contents of your binary package cache at ${PKGDIR}
     rm -r /var/cache/binpkgs/*

8. In the file or directory /etc/portage/binrepos.conf (if existing), update
   the URI in all configuration such that they point to 23.0 profile binhost 
   directories. The exact paths can be found in the table at [5], too.

9. Rebuild or reinstall from binary (if available) the following packages in
   this order, with the same version as already active:
     emerge --ask --oneshot sys-devel/binutils
   (you may have to run binutils-config and re-select your binutils now)
     emerge --ask --oneshot sys-devel/gcc
   (IMPORTANT: If this command wants to rebuild glibc first, do *not* let it do 
    that; instead, abort and try again with --nodeps added to the command line.)
   (you may have to run gcc-config and re-select your gcc now)
   and the C library, i.e. for glibc-based systems
     emerge --ask --oneshot sys-libs/glibc
   or for musl-based systems
     emerge --ask --oneshot sys-libs/musl

10. Re-run "emerge --info" and check if CHOST has changed compared to step 4.

If the CHOST has NOT changed, skip to step 13 (env-update). Otherwise, 

11. Recheck with binutils-config and gcc-config that valid installed versions
   of binutils and gcc are selected.

12. Check /etc/env.d, /etc/env.d/binutils, and /etc/env.d/gcc for files that
   refer to the *OLD* CHOST value, and remove them. 
   Examples how to do this can be found in the similar procedure at [6].

13. Run env-update && source /etc/profile

14. Re-emerge libtool:
   emerge --ask --oneshot libtool

15. Just for safety, delete the contents of your binary package cache at 
    ${PKGDIR} again:
     rm -r /var/cache/binpkgs/*

16. Rebuild world:
   emerge --ask --emptytree @world

[1] https://wiki.gentoo.org/wiki/Project:Toolchain/23.0_profile_transition
[2] https://wiki.gentoo.org/wiki/Project:Toolchain/23.0_profile_timeline
[3] https://www.gentoo.org/support/news-items/2019-06-05-amd64-17-1-profiles-are-now-stable.html
[4] https://www.gentoo.org/support/news-items/2022-12-01-systemd-usrmerge.html
[5] https://wiki.gentoo.org/wiki/Project:Toolchain/23.0_update_table
[6] https://wiki.gentoo.org/wiki/Changing_the_CHOST_variable#Verifying_things_work