Well, first off all, what do you have to loose? If it doesn't work out, you can still do a fresh install.
##Backup
It goes without saying that you need to backup important items. Maybe even do an archive of /etc, in case you want to look back.
Personally, whenever I try something radical, I rsync my root file system to a separate disk beforehand. Whenever something goes terribly wrong, I just rsync it back ;). Mount the root partition on a separate mount point, to prevent recursion to all mounted partitions. And run something like:
rsync -av --delete /mnt/root/ /mnt/backup
To restore:
rsync -av --delete /mnt/backup/ /mnt/root
Just make sure that the backup file system is a linux type (not FAT or NTFS), to transfer permissions, symlinks and file ownership correctly up and down.
Although never done personally, you could try the below options as a guideline. Some comments above suggest different compiler profiles, but most of that are just useflags to gcc and CFLAGS in make.conf, I don't see the real issue there.
#Option #1
What you could try, but no personal experience, is do it the repo.conf way. Create a separate directory, like /usr/gentoo and put the vanilla Gentoo portage tree there.
File /etc/portage/repos.conf/gentoo.conf:
[DEFAULT]
main-repo = gentoo
[gentoo]
location = /usr/gentoo
sync-type = rsync
sync-uri = rsync://rsync.gentoo.org/gentoo-portage
auto-sync = yes
priority 10
And something similar should exist for Funtoo, and with a lower priority. After you run emerge --sync, both trees will exist next to each other. If same version packages exist, the repo with higher priority wins (in theory). You can force package selection, by suffixing the desired repo like this:
emerge sys-devel/gcc::gentoo
Using this setup you can move to Gentoo step-by-step. The profiles from both repositories will be available for selection, so you can try out some emerge --pretend commands when selecting the Gentoo profiles, play around with useflags etc. Emerge gcc, portage from the Gentoo tree etc. If you just make sure that GCC is re-emerged with the same useflags (edit make.conf to your liking) and you keep the same CFLAGS, you probably don't even need to empty the system tree.
Maybe you want to read the GCC upgrade guide, and /usr/share/portage/config/make.conf.example.
Finally, you could drop the repo.conf entry for funtoo and do a emerge -uND --newrepo @world.
#Option #2
In the past, when I was doing some big profile change, I used this method.
- Make sure your system is completely up-to-date (
emerge -uND @world), handle the @preserved-rebuild set and depclean.
- Move the entries from
/var/lib/portage/world into a user defined set. This can be one set, or if you want to be organized, categories of sets. For instance, I created 3 sets, usable in separate stages of the process.
/etc/portage/sets/boot
sys-boot/grub
sys-kernel/gentoo-sources
[network tools etc]
/etc/portage/sets/admin
app-editors/vim
app-portage/gentoolkit
[...]
/etc/portage/sets/desktop
# All the rest
Make sure that /var/lib/portage/world and word_sets are both empty files after this migration.
- Run
emerge --depclean to get rid of all packages that where pulled in by @world
- For now, clean out
/etc/portage/package.use. (Move the file(s) somewhere if you intend using it later again.
- Comment out the
USE= line in make.conf
- Drop to a simple as possible profile. In gentoo it would be something like:
default/linux/amd64/17.0
emerge -uND @world && emerge --depclean You will be in the smallest configuration possible for Funtoo, smallest risk on conflicts.- Swap the portage tree to use Gentoo's one. (Probably in
repos.conf)
- This should give you the simplest Gentoo profile system
emerge -1 sys-apps/portage
emerge -1 sys-devel/gcc
emerge -e @system
emerge @boot And do what you need to do to conigure the kernel, grub etc. (follow the handbook) This should give you a completely reboot-able Gentoo system. Reboot if you want to test at this point.- Set your desired profile, re-enable useflags in
make.conf and maybe package specific flags in package.use
emerge -uND @world @admin @desktop && emerge --depclean: if this went ok, you have successfully transferred Funtoo to Gentoo!
Incompatibilities
To answer the remaining questions;
During the re-intallation of packages, portage will check if file in /etc/ are the originals or modified. If they are un-modified since installation, portage will just replace them. Same goes for files in /etc/init.d. These files, in the end, all belong to a package. A package rebuild should give the right version in the end.
Modified config files are protected by config-protect. These will need to be updated using tools like etc-update.
Note
I am aware this was an old question and probably doesn't help the OP anymore. However, the subject interests me. It would be nice if someone who came across this answer will give it an actual try :).
