Comment 1 for bug 1827929

IIUC

"proper partition setup" for callers of curtin is:

/boot/EFI partition *and* a grub_bios partition.

Something like:
    config:
      - id: main_disk
        type: disk
        ptable: gpt
        serial: disk-a
        name: main_disk
        wipe: superblock
        grub_device: true
      - id: bios_boot
        type: partition
        size: 1MB
        number: 1
      - device: main_disk
        flag: boot
        id: main_disk_part2
        number: 2
        size: 512M
        type: partition
        wipe: superblock

The curtin part would be to ensure that shim-signed *and* grub-pc packages are installed into target.