On Wed, Jan 31 2018, Ricardo Wurmus wrote:
> Finally, it is not clear where the efi partition should be 
> mounted.
> Should it be /mnt/boot/efi?  If so, should the configuration 
> file
> specify “/mnt/boot/efi” as the target?  Or should it be 
> “/boot/efi”?
>
> An example would be useful here.

We have an example in the manual at "(guix) Using the 
Configuration System" with the following sections:

  ;; Use the UEFI variant of GRUB with the EFI System
  ;; Partition mounted on /boot/efi.
  (bootloader (bootloader-configuration
                (bootloader grub-efi-bootloader)
                (target "/boot/efi")))

  ;; Assume the target root file system is labelled "my-root",
  ;; and the EFI System Partition has UUID 1234-ABCD.
  (file-systems (cons* (file-system
                         (device "my-root")
                         (title 'label)
                         (mount-point "/")
                         (type "ext4"))
                       (file-system
                         (device (uuid "1234-ABCD" 'fat))
                         (title 'uuid)
                         (mount-point "/boot/efi")
                         (type "vfat"))
                       %base-file-systems))

I know that's a completely different section where you're talking 
about, but maybe it can be referenced/copied in the installation 
section. I think we should mount the efi partition at /boot/efi 
during installation, to match the way things will be when we boot 
into the installed system.

Carlo