Hi Florian,
I think I still owed a final response in this thread, especially
after all your effort to help out.
In the end, I reinstallled Guix from scratch (luckily, I had a full
backup of my /home, and Guix makes it easy to restore your system
exactly as it was...), and switched to '(bootloader
grub-bootloader)'. That did the trick. I couldn't get the chroot
approach to work properly (maybe with more time, ...).
Looking back at the history of my system config, I used to have
(bootloader (grub-configuration (target "/dev/sda")))
for a long time. I don't actually remember how I ever ended up with
grub-efi-bootloader (little Guix time lately, I mostly just update
and check my e-mail these days), maybe I just copied from the manual
without thinking/ reading properly...
Thanks for your help, I still learned a few things, even though I
couldn't get it to work properly...
Thomas
