[Charlug] Kernel For Encrypted Root

Peter Senft peter.senft at hpss.de
Wed Jul 29 13:22:06 EDT 2009

Hi @all,

have an interesting issue creating a kernel (or creating a boot
configuration) for an encrypted system. I am using Ubuntu Jaunty and
used the installer to create the encrypted root file system etc. So
everything is nice and peachy when the system boots using the
distribution kernel. The system asks for the passphrase to unlock the
root partition.

But I don't want to use the distribution version of the kernel for
several reasons. Most important I don't want to use the initrd.

So far so good. As usual, I downloaded the latest kernel source tarball
from kernel.org and configured it, compiled it and installed it. It has
all the device mapper stuff in it that is needed (not as module) and
also everything from the cryptographic API.

But for some reason I don't get the question for the passphrase during
boot?! All I get is a kernel panic because the root cannot be found?! I
am using basically the same boot configuration in GRUB as I use for the
Ubuntu kernel:
title           Ubuntu 9.04, kernel
uuid            13228aa4-f8a3-46b7-aeb9-fc662746b4a6
kernel          /vmlinuz- root=/dev/mapper/obelix-root ro

What am I missing here. Google and other search engines are not helpful
here at all. I have the feeling some tool or script is missing that
unlocks the root partition but can't find anything useful.

cu hps

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