Project-1: Firmware Update on RBA5D2x using RAU Modules: - Application Updates Only - RFS Update Only - Kernel Update Only - Bootloader Update Only - Full Image Project-2: Porting FreeRTOS on RB-A5D2x Porting of FreeRTOS on RB-A5D2x using gcc toolchain reference code can be taken from FreeRTOS Cortex-A5 port demonstrated on a SAMA5D3 MPU from Atmel Project-3: Porting Zephyr RTOS on RB-A5D2x Porting of Zephyr on RB-A5D2x Ref Link...

From log it seems kernel is not able to find RFS which should on the second partition of your SD Card. Follow any tutorial for preparing your Sdcard https://elinux.org/RPi_Easy_SD_Card_Setup