If N1SDP SW release version is 2021.04.26 and older, the second reboot (after Ubuntu server installation) grub will lead to a grub console. The reason for that is following:
"apt-get install" of grub-efi-arm64 on Ubuntu 18.04 installs GRUB version 2.04. Previously the version was 2.02.
GRUB 2.04 has many fixes for secure boot and this explicitly requires to select between:
--uefi-secure-boot (this is the default) or --no-uefi-secure-boot
-uefi-secure-boot
--no-uefi-secure-boot
Since N1SDP SW stack doesn't provide a signed file, GRUB enters the grub console.
<workspace>/ubuntu/build-scripts/helpers/platforms/n1sdp/ubuntu/init script should be modified as following:
grub-install --no-uefi-secure-boot || true
After this modification rebuild ubuntu image and create a bootable media.
N1SDP SW version 2021.05.26 and newer already has this fix.