hello @yairhav,
Jetson Xavier NX brings three UARTs out to the main connector; there’re 3 UARTs available, UART0 to M2; UART1 to 40-PIN; UART2 to debug.
you may access NX Product Design Guide , and check [Table 11-7] for Xavier NX uart pin descriptions.
you should modify misc configuration file to tell the bootloader to not use a debug UART,
in the case of using other UART# as debug UART, please change the value in kernel dts also for bootparam and serial node as current UART0.
please also refer to similar discussion thread for reference, Topic 170116.
thanks