clr-boot-managers fails to install boot loader when used in mkosi

[DaanDeMeyer]

Describe the bug

I've been trying to setup extended CI for mkosi. One of the last remaining failures is Clear Linux. More specifically, installing its boot loader fails.

To Reproduce Steps to reproduce the behavior:

git clone https://github.com/DaanDeMeyer/mkosi.git --branch ci-bootable
cd mkosi
sudo ./mkosi -d clear --bootable -f

Expected behavior

Installation of Clear Linux boot loader succeeds.

Environment (please complete the following information):

• Clear Linux OS Version: Arch Linux/Github Actions Ubuntu Focal
• clr-boot-manager Version: Whatever swupd-extract installs
• Platform: N/A

Block Devices:

• List of Block Devices: N/A

Additional context

A log of a mkosi run on my laptop with strace enabled: mkosi.log

Link to Github Actions run with strace enabled: https://github.com/systemd/mkosi/runs/937404991?check_suite_focus=true

The error messages singled out:

write(2, "[FATAL] cbm (../src/bootman/sysc"..., 85[FATAL] cbm (../src/bootman/sysconfig.c:L277): sysconfig insane: Missing root device
) = 85
write(2, "[FATAL] cbm (../src/bootman/upda"..., 73[FATAL] cbm (../src/bootman/update.c:L389): Failed to install bootloader
) = 73

[DaanDeMeyer]

Nvm, just had to mount some extra stuff from /dev (/dev/block, /dev/disk)