Comment 4 for bug 551055

Alright, I worked through the odds and ends, and got the automagic for initrd and grub working. I have a btrfs root partition on top of lvm, itself on top of dm-crypt device, itself on top of raid. If your config similarly involves btrfs root partition on top of crypto, this is what you need to do to boot it:

1) Download patch from comment 3 above, save it to /tmp. Apply it:
cd /usr/share/initramfs-tools/scripts/local-top
sudo patch -p1 < /tmp/cryptsetup.ubuntu_karmic.diff

2) Add btrfs, crc32c, libcrc32c, and zlib_deflate to /etc/initrams-tools/modules, one per line.

3) Regenerate initrd images for all kernels (if you have any manually assembled initrd images which work, you might want to back them up before running this):
sudo update-initramfs -c -k all

4) Edit grub-mkconfig and /etc/default/grub, as described in comment 4 of bug #450260. Regenerate grub configuration (not sure if it'll work with grub-legacy, I tested with grub-pc):
sudo update-grub

After this procedure things will work correctly even when installing future kernel updates (if any) for Karmic, and bootable configuration will be auto-generated.