Available in a git repository.
Repository: catalyst-swc
Browsable repository: catalyst-swc
Author: W. Trevor King

Catalyst is a release-building tool for Gentoo. If you use Gentoo and want to roll your own live CD or bootable USB drive, this is the way to go. As I've been wrapping my head around catalyst, I've been pushing my notes upstream. This post builds on those notes to discuss the construction of a bootable ISO for Software Carpentry boot camps.

Getting a patched up catalyst

Catalyst has been around for a while, but the user base has been fairly small. If you try to do something that Gentoo's Release Engineering team doesn't do on a regular basis, built in catalyst support can be spotty. There's been a fair amount of patch submissions an gentoo-catalyst@ recently, but patch acceptance can be slow. For the SWC ISO, I applied versions of the following patches (or patch series) to 37540ff:

Configuring catalyst

The easiest way to run catalyst from a Git checkout is to setup a local config file. I didn't have enough hard drive space on my local system (~16 GB) for this build, so I set things up in a temporary directory on an external hard drive:

$ cat catalyst.conf | grep -v '^#\|^$'
digests="md5 sha1 sha512 whirlpool"
options="autoresume kerncache pkgcache seedcache snapcache"

I used the default values for everything except sharedir, snapshot_cache, and storedir. Then I cloned the catalyst-swc repository into /mnt/d/tmp/catalyst.

Portage snapshot and a seed stage

Take a snapshot of the current Portage tree:

# catalyst -c catalyst.conf --snapshot 20130208

Download a seed stage3 from a Gentoo mirror:

# wget -O /mnt/d/tmp/catalyst/builds/default/stage3-i686-20121213.tar.bz2 \
>   http://distfiles.gentoo.org/releases/x86/current-stage3/stage3-i686-20121213.tar.bz2

Building the live CD

# catalyst -c catalyst.conf -f /mnt/d/tmp/catalyst/spec/default-stage1-i686-2013.1.spec
# catalyst -c catalyst.conf -f /mnt/d/tmp/catalyst/spec/default-stage2-i686-2013.1.spec
# catalyst -c catalyst.conf -f /mnt/d/tmp/catalyst/spec/default-stage3-i686-2013.1.spec
# catalyst -c catalyst.conf -f /mnt/d/tmp/catalyst/spec/default-livecd-stage1-i686-2013.1.spec
# catalyst -c catalyst.conf -f /mnt/d/tmp/catalyst/spec/default-livecd-stage2-i686-2013.1.spec


To make the ISO bootable from a USB drive, I used isohybrid:

# cp swc-x86.iso swc-x86-isohybrid.iso
# isohybrid iso-x86-isohybrid.iso

You can install the resulting ISO on a USB drive with:

# dd if=iso-x86-isohybrid.iso of=/dev/sdX

replacing replacing X with the appropriate drive letter for your USB drive.

With versions of catalyst after d1c2ba9, the isohybrid call is built into catalysts ISO construction.