 |
Title: Booting Gentoo on a BTRFS from multiple LUKS devices |
|
Author: Solène |
|
Date: 02 January 2023 |
|
Tags: linux gentoo btrfs |
|
Description: In this article, I share my discoveries in booting Gentoo |
|
installed on a BTRFS filesystem using multiple-devices stored on LUKS |
|
partitions. |
|
|
|
# Introduction |
|
|
|
This is mostly a reminder for myself. I installed Gentoo on a machine, |
|
but I reused the same BTRFS filesystem where NixOS is already |
|
installed, the trick is the BTRFS filesystem is composed of two |
|
partitions (a bit like raid 0) but they are from two different LUKS |
|
partitions. |
|
|
|
It wasn't straightforward to unlock that thing at boot. |
|
|
|
# Fix grub error |
|
|
|
Grub was trying to autodetect the root partition to add |
|
`root=/dev/something`, but as my root filesystem requires |
|
`/dev/mapper/ssd1` and `/dev/mapper/ssd2`, it was simply adding |
|
`root=/dev/mapper/ssd1 /dev/mapper/ssd2`, which is wrong. |
|
|
|
This required a change in the file `/etc/grub.d/10_linux` where I |
|
entirely deleted the `root=` parameter. |
|
|
|
# Compile systemd with cryptsetup |
|
|
|
A mistake I made was to try to boot without systemd compiled with |
|
cryptsetup support, this was just failing because in the initramfs, |
|
some systemd services were used to unlock the partitions, but without |
|
proper support for cryptsetup it didn't work. |
|
|
|
# Linux command line parameters |
|
|
|
In `/etc/default/grub`, I added this line, it contains the UUID of both |
|
LUKS partitions needed, and a `root=/dev/dm-0` which is unexpectedly |
|
the first unlocked device path, and `rd.luks=1` to enble LUKS support. |
|
|
|
``` |
|
GRUB_CMDLINE_LINUX="rd.luks.uuid=24682f88-9115-4a8d-81fb-a03ec61d870b rd.luks.u… |
|
``` |
|
|
|
# Run Dracut and grub |
|
|
|
After the changes, I did run `dracut --force --kver |
|
5.15.85-gentoo-dist` and `grub-mkconfig -o /boot/grub/grub.cfg` |
|
|
|
# Conclusion |
|
|
|
It's working fine now, I thought it would require me to write a custom |
|
initrd script, but dracut is providing all I needed, but there were |
|
many quirks on the path with no really helpful message to understand |
|
what's failing. |
|
|
|
Now, I can enjoy my dual boot Gentoo / NixOS (they are quite |
|
antagonists :D), but they share the same filesystem and I really enjoy |
|
this weird setup. |
