[bug#48314] [PATCH v3] Install guix system on Raspberry Pi

[phodina]

Thanks Stefan for the updated patches!

I've applied them and build the system. However,
I'm unable to test the system as there is an error when invoking `guix system 
init` command:

$ sudo -E ./pre-inst-env guix system init --target=aarch64-linux-gnu 
gnu/system/examples/raspberry-pi-64.tmpl /mnt
/gnu/store/hhb5l2f5287xmfzz4jgvi15kb9bcqi33-system
/gnu/store/fiq006ykhc0dkninzz5gxl2nh3vzc37p-grub.cfg

initializing operating system under '/mnt'...
copying to '/mnt'...
populating '/mnt'...
guix system: error: symlink: Operation not permitted: "/boot/efi/gnu/store"

$ sudo fdisk /dev/mmcblk0

Welcome to fdisk (util-linux 2.37.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

This disk is currently in use - repartitioning is probably a bad idea.
It's recommended to umount all file systems, and swapoff all swap
partitions on this disk.

Command (m for help): p

Disk /dev/mmcblk0: 29.12 GiB, 31267487744 bytes, 61069312 sectors
Disk model: 1081CS0
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device     Boot  Start      End  Sectors  Size Id Type
/dev/sda1         2048   526335   524288  256M 83 Linux
/dev/sda2       526336 61069311 60542976 28.9G 83 Linux

$ mount
/dev/mmcblk0p2 on /mnt type ext4 (rw,relatime)
/dev/mmcblk0p1 on /mnt/boot type vfat 
(rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)

I have these 2 remarks:
1) Why does it point to "/boot/efi/gnu/store" and not 
"/mnt"/boot/efi/gnu/store"?
2) Symlink from ext4 "Guix" partition will not work on another vfat "EFI" 
partition.

Do you know how to fix this issue?

----
Petr