efivarfs fails with `No such device` when EFI runtime is missing

[Paul Menzel]

Dear Linux folks,


I migrated a 32-bit GNU/Linux installation from BIOS to EFI. Trying to 
edit the entries in UEFI’s Boot Manager with `efibootmgr`, I got the error:

    EFI variables are not supported on this system

`sudo modprobe efivarfs` fails with

    No such device

After several tries, I found

    [    0.000000] efi: No EFI runtime due to 32/64-bit mismatch with 
kernel

logged by Linux, and then I found the Stack Overflow thread *How could 
32bit kernel read efivars from 64bit UEFI?* [1].

I would have thought, setting EFI variables is just directly writing to 
some storage. But probably not.

Could the error message for the efivarfs load failure be improved, that 
*device* means the runtime service (if I am not mistaken)?


Kind regards,

Paul


[1]: 
https://stackoverflow.com/questions/46610442/how-could-32bit-kernel-read-efivars-from-64bit-uefi