I was trying to finalize a backup device to gift to my dad over Christmas. We’re planning to use each other for offsite backup, and save on the cloud costs, while providing a bridge to each other’s networks to get access to services we don’t want to advertise publicly.

It is a Beelink ME Mini running arch, btrfs on luks for the os on the emmc storage and the fTPM handling the decryption automatically.

I have built a few similar boxes since and migrated the build over to ansible, but this one was the proving ground and template for them. It was missing some of the other improvements I had built in to the deployed boxes, notably:

• zfs on luks on the NVMe drives
• the linux-lts kernel (zfs compatibility)
• UKI for the secureboot setup

I don’t know what possessed me, but I decided that the question marks and tasks I had in my original build documentation should be investigated as I did it up, I was hoping to export some more specific configuration to ansible to the other boxes once done. I was going to migrate manually to learn some lessons.

I wasn’t sure about bothering with UKI. I wanted zfs running, and that meant moving to the linux-lts kernel package for arch.

Given systemd-boot’s superior (at current time) support for owner keys, boot time unlocking and direct efi boot, I’ve been using that. However, it works differently if you use plain kernels, compared to if you use UKI. Plain kernels use a loader file to point to the correct locations for the initramfs and the kernel, which existed on this box.

I installed the linux-lts package, all good. I removed the linux kernel package, and something in the pacman hooks failed. The autosigning process for the secure-boot setup couldn’t find the old kernel files when it regenerated my initramfs, but happily signed the new lts ones. Cool, I thought, I’ll remove the old ones from the database, and re-enroll my os drive with systemd-cryotenroll after booting on the new kernel (the PCRs I’m using would be different on a new kernel, so auto-decrypt wouldn’t work anyway.)

So, just to be sure, I regenerated my initram and kernel with mkinitcpio -p linux-lts, everything worked fine, and rebooted. I was greeted with:

Reboot to firmware settings

as my only boot option. Sigh.

Still, I was determined to learn something from this. After a good long while of reading the arch wiki and mucking about with bootctl (PITA in a live CD booted system) I thought about checking my other machines. I was hoping to find a bootctl loader entry that matched the lts kernel I had on other machines, and copy it to this machine to at least prove to myself that I had sussed the problem.

After checking, I realised no other newer machine had a loader configuration actually specifying where the kernel and initram were. I was so lost. How the fuck is any of this working?

Well, it turns out, if you have UKI set up, as described, it bundles all the major bits together like the kernel, microcode, initram and boot config options in to one direct efi-bootable file. Which is automatically detected by bootctl when installed correctly. All my other machines had UKI set up and I’d forgotten. That was how it was working. Unfortunately, I had used archinstall for setting up UKI, and I had no idea how it was doing it. There was a line in my docs literally telling me to go check this out before it bit me in the ass…

…

• [x] figure out what makes uki from archinstall work ✅ 2025-09-19
• It was systemd-ukify

…

So, after that sidetrack, I did actually prove that the kernel could be described in that bootctl loader entry, then I was able to figure out how I’d done the UKI piece in the other machines, and applied it to this one, so it matched and updated my docs…

…

• IT WASN’T ukify

UKI configuration is in mkinitcpio default configs, but needs changing to make it work.

vim /etc/mkinitcpio.d/linux-lts.preset 

…

Turns out my Christmas wish came true, I learned I need to keep better notes.