Hello, @hittzt
Thanks for your confirmation.
I tested it without m7boot added to the local.conf, and seems there are no issues, the possible reason for the issue you met seems to be secure boot verification fail.
While you added m7boot to the local.conf, then a small m7 bootloader would be appended, the boot image could be changed to the bl2_w_dtb.s32-sdcard.m7 instead of the original one, but when booted to Linux, while enabling secure boot, the command is like:
hse-secboot -s -d /dev/mmcblk0 --bl2_key /etc/keys/secboot/bl2_rsa2048_public.pem --bl31_key -:0x010700 --bl33_key -:0x010700 --bl2_sign /etc/keys/secboot/bl2-signature.bin-sdcard --bl2_bin /etc/keys/secboot/bl2_w_dtb.bin-sdcard
Which does not match the boot image specified.
From my understanding, the default secboot operation steps are only reference for default settings, if there are some additional configurations added, there may be issues.
BR
Chenyin