[bug#62223] Tested locally

[Sergey Trofimov <sarg@sarg.org.ru>]

I have created an image and verified that it boots on qemu with 
proper bios.
Then I've baked an image of my real system configuration and used 
it to reprovision my laptop.

vm.scm
--8<---------------cut here---------------start------------->8---
...
  (bootloader
   (bootloader-configuration
    (bootloader grub-efi-bootloader)
    (targets '("/boot"))))
  (file-systems
   (cons*
    (file-system
      (mount-point "/")
      (device (file-system-label "Guix_image"))
      (type "ext4"))
    (file-system
      (mount-point "/boot")
      (device (file-system-label "GNU-ESP"))
      (type "vfat"))
    %base-file-systems))
...
--8<---------------cut here---------------end--------------->8---

testing it with:
--8<---------------cut here---------------start------------->8---
guix system image --image-type=efi-raw vm.scm

qemu-system-x86_64 \
    -bios $(guix build ovmf)/share/firmware/ovmf_x64.bin \
    -drive file=$HOME/vm.img,if=virtio
--8<---------------cut here---------------end--------------->8---