I have an old router which runs Linux and I'd like to have a serial console on. This used to work fine, but after a firmware update, I can now only get output on the console and cannot give any input back to the device. During boot there is a line that says "Console input is disabled" that wasn't there before.
Without changing the firmware, how do I re-enable input on the serial console?
... my attempts so far ...
I can log in over the LAN and load any files (and cross compile tools if need be), and there is a small non-volatile user flash partition, so any solution requiring me to write a quick program using ioctl or whatnot is fine. The embedded Linux has the system files like
/sys/devices/platform/serial8250.0 and so on in case that is useful. The files
/dev/tty all have read and write permissions. Running
getty -L 115200 ttyS0 makes a login prompt appear on the serial console, but I can't get it to accept any input. Adding the line
inittab makes busybox give a shell prompt ... but again, the serial console won't take input.
Kernel command line: root=/dev/ram rw init=/init console=ttyS0,115200
speed 38400 baud; line=0;
along with a bunch of unimportant looking settings,
stty -a -F /dev/ttyS0 gives
speed 115200 baud; stty: /dev/ttyS0 line = 0;
(and a whole bunch of settings that don't look important, but I'll type them up if people need them.)
I'm at a loss here, so I'm not sure what information is needed.
Any ideas for solving this puzzle? I have a feeling there is something simple I forgot to try.