[gentoo-dev] [RFC] First (experimental) 17.1 profiles news item for review

[Michał Górny]

Hello, everyone.

The first news item I'd like to submit for 17.1 profiles follows.
The item is aimed at ~amd64 users who'd like to test the new profiles.
When they become stable, a separate news item for all our users will be
published.

===

Title: Experimental amd64 17.1 profiles up for testing
Author: Michał Górny <mgorny@g.o>
Posted: 2017-12-xx
Revision: 1
News-Item-Format: 2.0
Display-If-Keyword: ~amd64

A new set of 17.1 amd64 profiles has been added to the Gentoo
repository. Those profiles switch to a more standard 'no SYMLINK_LIB'
multilib layout, and require explicit migration as described below. They
are considered experimental at the moment, and have a fair risk
of breaking your system. We would therefore like to ask our users to
test them on their non-production ~amd64 systems.

In those profiles, the lib->lib64 compatibility symlink is removed.
The 'lib' directory becomes a separate directory, that is used
for cross-arch and native non-library packages (gcc, clang) and 32-bit
libraries on the multilib profile (for better compatibility with
prebuilt x86 packages).

Migration from both 13.0 and 17.0 profiles is supported. In case
of the former, please read the news item for 17.0 upgrade first
and enable gcc 6.4.0 or newer first as explained there.

The migration is performed using app-portage/unsymlink-lib tool.
The following steps can be used to upgrade your system:

1. Sync and upgrade your system to the newest package versions
   to reduce the risk of issues.

2. Install the tool, e.g. via 'emerge -1v app-portage/unsymlink-lib'

3. Run 'unsymlink-lib --analyze' and check the output for obvious
   mistakes. If you need to perform any changes to the system, remember
   to run 'unsymlink-lib --analyze' again afterwards.

[past this point do not call emerge or modify /usr manually]

4. This is a very good time to make a backup.

5. Run 'unsymlink-lib --migrate'. You can add '--pretend' first to see
   what is going to happen.

6. Reboot your system and see if it still boots. Check if important
   programs work. In particular, check if e.g. 'emerge --info' works
   (but do not install anything). If you hit any serious problems,
   you can use 'unsymlink-lib --rollback' to revert the changes
   and return to step 3.

7. Run 'unsymlink-lib --finish'. You can add '--pretend' first to see
   what is going to happen but note that you're going to see a very long
   list of files to remove.

8. Switch the profile, e.g.:

     eselect profile set --force default/linux/amd64/17.1/desktop

[at this point you can start using emerge again]

9. Rebuild sys-devel/gcc. If you are switching from 13.0 profiles,
   rebuild sys-devel/binutils and sys-libs/glibc afterwards.

10. If you are using a multilib profile, rebuild all 32-bit packages.
    This can be done using:

      emerge -1v /lib32 /usr/lib32

    Alternatively, if you are switching from one of the 13.0 profiles
    you can rebuild all packages as detailed in the 17.0 news item.

11. Once the last 32-bit package is rebuilt, your package manager
    should remove the orphaned /lib32 and /usr/lib32 symlinks. If that
    does not happen, remove them manually.

For known issues, please see bug #506276 [1]. If you have any problems
with the new profiles or the migration procedure, please report a bug
and make it block the tracker.

[1]:https://bugs.gentoo.org/506276

-- 
Best regards,
Michał Górny