Comment 3 for bug 551055

Vincent, here's the gutschke's patch adapted for Ubuntu Karmic. Normally you'd install it by saving it to /tmp and running the following from the shell:

cd /usr/share/initramfs-tools/scripts/local-top
sudo patch -p1 < /tmp/cryptsetup.ubuntu_karmic.diff
sudo update-initramfs -c -k all

However, it likely won't be enough on its own, because of bug #450260. Till that one is fixed, you'll need to apply this patch, and still assemble initrd manually (to make sure it contains correct conf/conf.d/cryptroot, and btrfs.ko with libcrc32c.ko and libcrc32c.ko dependencies, and all needed crypto modules), and edit grub.cfg or menu.lst by hand. And may have to do the GRUB_DEVICE trick mentioned in #450260 discussion.