As developers expand Gentoo to new architectures and platforms, they may find there isn't any real collection of knowledge which explains all the little details of Portage and moving a platform into the experimental release stage. This document aims to address that. Here we port Gentoo Linux to the SuperH (sh) architecture, but the details should be pretty straightforward for other arches/operating systems.

This is the hardest step by far (really!). There are two ways to get going. You can start with an existing Linux port out there (Debian, RedHat, some random hobbyist distro, etc...), or you can cross compile the entire system. The first route is the easiest, so we will cover that first. Simply boot up the system with the existing port and make sure it has all the important packages installed for development. A quick checklist:

• binutils
• gcc
• glibc
• python
• rsync
• wget
• tar
• gzip
• bzip2
• bash (must be version 3 or newer)

Once you have these packages, you can easily install Portage. A script to do so can be found here. Simply download it and run:

# bash ./bootstrap-portage

Then we need to create a profile for our new arch.

# mkdir -p /usr/local/portage/profiles/default/linux/sh
# cd /usr/local/portage/profiles/default/linux/sh
# echo '..' > parent
# cat << EOF > make.defaults
ARCH="sh"
ACCEPT_KEYWORDS="sh"
GRP_STAGE23_USE="pam"
EOF
# cd /etc
# ln -s ../usr/local/portage/profiles/default/linux/sh make.profile
# "PORTDIR_OVERLAY=/usr/local/portage" >> make.conf

Finally, sync up and we should have our Portage tree!

# emerge --sync

The next step is to prepare a seed for Catalyst, the tool used to create Gentoo releases. Since none of the ebuilds in Portage know about our new arch, we can cheat with package.keywords and using x86 as our reference arch.

# mkdir /etc/portage
# for p in $(env USE="-*" ACCEPT_KEYWORDS=x86 \
	emerge system -qep --columns | awk '($1 ~ /ebuild/) {print $4}') ; do \
	echo "${p} x86" >> package.keywords ; \
done

Then we simply emerge our system into a new root and create a seed tarball with the result:

# env ROOT=~/gentoo-seed/ USE="-*" emerge system
# tar jpcf ~/seed.tar.bz2 ~/gentoo-seed/

Now, take the list generated in package.keywords, and add the sh KEYWORD to them. If you use ekeyword from the app-portage/gentoolkit-dev package, things will go much faster. Once your Portage tree has been updated, create a catalyst snapshot:

# catalyst -C target=snapshot version_stamp=sh

Before we can make stages with catalyst, we need to teach catalyst something about our new arch. Go into /usr/lib/catalyst/arch/ and copy one of the small .py modules to sh.py. Then edit it to reflect the sh architecture. Finally, edit the generic_stage_target.py file in /usr/lib/catalyst/modules/. You just have to update the targetmap and machinemap variables.

Then try building a stage1 tarball with catalyst and the seed:

# mkdir -p /var/tmp/catalyst/builds
# mv ~/seed.tar.bz2 /var/tmp/catalyst/builds/
# catalyst -C \
	snapshot=sh version_stamp=sh \
	subarch=sh profile=default/linux/sh \
	rel_type=default target=stage1 \
	source_subpath=seed

If everything goes well, you should end up with a stage1 tarball from which you can then make stage2 and stage3 tarballs.

If you don't like the idea of running catalyst by hand, you can grab the script that does the work for you. It will generate the Portage snapshot and stage[123] tarballs for you. Simply edit the settings at the top of the script (see above for the proper settings). You will still have to move the seed tarball to the catalyst directory.

If we don't want all this work to be for nothing, we have to share it. Here's what needs to be updated so you don't start committing half-broken work (and making other developers very angry).

Our first profile was just a 'make it work' solution. Now you have to create a much more complete one. After you've committed the profile, update the following files in the /usr/portage/profiles/ subdirectory:

• arch.list
• profiles.desc

You should declare the profile status in profiles.desc as "dev" for now (it'll keep people from yelling at you, trust me on this).

At this point, you should be able to start updating ebuilds in the tree with the new KEYWORD.