On 2022-11-06 23:21, Felix Lechner wrote:
> My diagnosis was wrong. Your EFI variables are accessible. How about
> the output of 'efibootmgr'?

The hardware is a 2009 macbook, I believe can only boot through EFI (no 
BIOS compatibility mode or anything, AFAIU).  efibootmgr reports 
(ominously)

BootCurrent: 0000
No BootOrder is set; firmware will attempt recovery
BootFFFF*

I've attached the grub.cfg of the first failing generation (that is: I 
managed to boot into this generation, but now 'guix system reconfigure' 
runs into the EFI issue).

Somewhat embarrassingly, the last fully working generation is also the 
last generation with the linux-libre kernel. I don't know if you'd still 
like to help me try to restore a working system with linux-libre, or if 
that also conflicts with this list's policy on discussion of nonfree 
software.  If not, that is of course understandable, and I'll try to 
figure it out another way (or, more likely given my limited experience 
in this area, attempt a complete fresh install ;-) ).

Thomas

> Can you post the Grub configuration of the failing setup? It should
> show the past (good) configurations?
> 
>> I've also read about rEFInd
> 
> I have used that program to boot into a Linux kernel via its EFI stub,
> but it is my least favorite option.
> 
> Kind regards
> Felix Lechner