My lab deals mainly with RHEL and SLES. When building an image I setup both with a small 512MiB EFI boot partition and ext4 root partition. Install the OS and basic packages.
We only have UEFI systems so testing legacy boot is not doable.
When deploying a RHEL image it will reboot into disk without issue and the disk efi entry is already there, but with sles it is missing.
Is there some required setting on the OS I need? Maybe RHEL sets some flag on disk?
Also, is there a possibility to have the OS boot directly without rebooting the system using switch_root /sbin/init, this is what warewulf v3 did. This allowed me to run any changes before rebooting including makeing sure efi boot params were correct using efibootmgr.