following -current on rpi4 with zfs-on-root

Hi,

In /usr/src/UPDATING, there's this concerning
zroot booting after buildworld kernel cycle:

+++++
2.) update the ZFS boot block on your boot drive

    The following example updates the ZFS boot block on the
    freebsd-boot partition of a GPT partitioned drive ada0:
    "gpart bootcode -p /boot/gptzfsboot -i $N ada0"
    The value $N will typically be 1 (if booting from BIOS) or 2 (if
    booting from EFI).
+++++

BIOS in a rpi4 context I read as u-boot. I thought it hands the boot process
over to bootaa64.efi, which I thought was efi. Is this correct?
Its initial boot screen shows u-boot. Is this bios or efi?

TIA,
--