Verdin has an integrated Serial-to-USB converter that lists 4 serial ports on your computer. The highest index is the Linux serial console. Example, if you see /dev/ttyUSB0, /dev/ttyUSB1, /dev/ttyUSB2 and /dev/ttyUSB3 listed, then /dev/ttyUSB3 is the serial console.
This explains which is Linux serial console (/dev/ttyUSB3), but it’s not clear which is Cortex-M serial port (it should be uart_4 peripheral).
Moreover, opening a temrinal on ttyUSB0 resets the device (as described here) and so I suppose that this is either the FDTI JTAG or FTDI GPIO.
Is it possible to have a list of what are all the other ports /dev/ttyUSB0, /dev/ttyUSB1 and /dev/ttyUSB2?
Only one suggestion from my side (not sure if it’s general, or it applies to Verdin only).
All the examples on this page refer to /dev/ttyUSB0 but if you do this, the device reboots (because /dev/ttyUSB0 is connected to the GPIOs to control the target).
I would suggest changing the examples, referring to /dev/ttyUSB3 (which is Cortex-A debug UART).