EFI GRUB configuration ignores platform, has issues

[Isaac van Bakel <ivb@vanbakel.io>]

Hi Guix,

I've been wrestling with a fresh real install for the past day or so.

Currently, the system seems to initialize fine with my config, with the 
exception of GRUB.
I wanted to get grub-efi working, so I added two things on top of the 
bare-bones config:

(use-modules (gnu packages)) at the start.

(grub (specification->package "grub-efi")) to my grub-configuration.

This all seems to work about as I expect - the grub install doesn't 
complain about a lack of a BIOS partition, and it tries its best.
The issue seems to be in part that grub-install for EFI tries to use 
i386-pc for a platform, even when I pass --system=x86_64-linux to guix 
system init, and the USB is a x86_64 one.
It tries to access a directory in /gnu/store 
/<grub-efi>/lib/grub/i386-pc which doesn't exist, and promptly fails.

If I copy over the x86_64 folder to i386-pc, the install gets past this 
point, and I can go on to boot as (apparently) normal.
However, I'm not sure whether to trust the boot totally, and I'm worried 
about it being unreproducable without manual effort.

Is there anything I can do?

Thanks,
Isaac