Enabling the UART port on a Raspberry PI

Question

what does this statement imply: By default the serial port on the Raspberry PI is configured for console input/output.

dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait
why should we delete the bold parts of this line, please explain the mechanism going on behind. If we include extra spaces or any erroneous character will it effect the functioning of raspberry pi

Answer 1

if you delete this part ("console=ttyAMA0,115200 kgdboc=ttyAMA0,115200"), the UART is free (not really see note ...), you can use it for other task like connect a sensor for example, if you keep this parameter you can read the kernel bootlog of your OS linux on the serial port (UART).

if your port is wrong (erroneous character) it will be ignored by the linux kernel.

note : for freeing the serial port you must to commented out the line "2:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100" in the file /etc/inittab, this line enable the linux console on the serial port (login/logout/linux command)