I have Ubuntu 15.04 with a default full disk encryption installed on my chromebook Pixel with linux-samus kernel patch and everything is working fine. I've just tried compiling a newer version of the kernel (4.1), but when I'm trying to boot it I'm getting an error where I would normally enter the disk encryption password:
Cannot initialize device-mapper. Is dm_mod kernel module loaded?
I'm guessing something is missing in kernel config, any idea what that is? This is the kernel config file.