[bug#48314] [PATCH v5] Install guix system on Raspberry Pi

[phodina]

Hi Stefan,

I've recently encoutered an issue on Raspberry Pi 4 when attaching USB Hard 
drive.

I formatted it with fat32 and ext4. Ran `guix system init config.scm /init`.

I selected `(initrd-modules (list "xhci_pci" "pcie_brcmstb"))` in the config 
and rebooted.

Unfortunately I get error about missing file:

```
error: file /gnu/store/xxx-raw-initrd/initrd.cpio.gz not found
Press any key to continue ...
```

After that I get kernel panic.

Shoudn't the initrd be placed in the EFI partition? That way you get the 
modules in order to  mount the rootfs.

Should I copy it and modify the Grub entry?

The goal here is to run completly from USB then there won't be any need for SD 
card.

----
Petr