Serial Console

Output to Serial Console

Make sure the kernel is started with the following parameter…

console=ttyS0,115200

Change Size (rows/cols)

Often the expected size of the TTY session isn't what you would want and feels constrained. You can change a bunch of setting using the stty command. Below will change the number of columns because that is what I most often feel I need to change…

stty cols 140

Dual Output

It is possible to have the kernel write to both the standard pseudo-terminal (tty0) and the serial console (ttyS0) by adding the following kernel parameters…

console=ttyS0,9600 console=tty0

View Console

It is possible to view serial console output using the screen command. With a USB-to-Serial adapter plugged in you may see a device called something like /dev/tty.usbserial-AG0JL5ZB that will act as the tty device.

screen /dev/tty.usbserial-AG0JL5ZB 115200,cs8,ixon

Parameters explained from man screen

Parameter	Description
<baud_rate>	This affects transmission as well as receive speed (usually 300, 1200, 9600 or 19200)
cs8 or cs7	Specify the transmission of eight (or seven) bits per byte
ixon or -ixon	Enables (or disables) software flow-control (CTRL-S/CTRL-Q) for sending data
ixoff or -ixon	Enables (or disables) software flow-control for receiving data
istrip or -istrip	Clear (or keep) the eight bit in each received byte