I tried by adding the modules into the /etc/initramfs-tools/modules (man
initramfs.conf)
echo -e "crypto\nxts\n\ndm-crypt\naes" >> /etc/initramfs-tools/modules
and by modifying the /etc/default/grub file a little (
https://wiki.archlinux.org/index.php/GRUB#Root_encryption
https://wiki.archlinux.org/index.php/Dm-crypt_with_LUKS#Kernel_parameter_configuration_of_the_bootloader
) like this:
[... snip ...]
GRUB_CMDLINE_LINUX="cryptdevice=/dev/sda5:cryptoroot"
[... snip ...]
so that I get /boot/grub/grub.cfg
[... snip ...]
linux /vmlinuz-3.5.0-36-generic cryptdevice=/dev/sda5:cryptoroot
root=/dev/mapper/Lap-root ro splash quiet $vt_handoff
[... snip ...]
I also added echo "insmod lvm" to /etc/grub.d/00_linux , just in case.
