There two conversations. Maybe you don’t consider them bugs:
If there is a data nvme disk without OS files or /boot, the emmc will boot but the /boot on the emmc will be ignored. See attached boot.1.txt. Bootloader attempted to find extlinux.conf from nvme but there is none, so it moves on to boot the kernel partitions from emmc. Even though boot order says nvme, emmc, it never moves on to the extlinux on the emmc. boot.1.txt (31.6 KB)
I pulled out the nvme drive, now the extlinux.conf on the emmc is being read, but there is an compatibility issue. Now it is mandated to have an APPEND line to define root device or else boot will HALT.