how to re-enable input on a serial console
The busybox example inittab
looks a little different,
# Example of how to put a getty on a serial line (for a terminal)
#
#::respawn:/sbin/getty -L ttyS0 9600 vt100
#::respawn:/sbin/getty -L ttyS1 9600 vt100
could you give this a try?
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CuriousPuzzleSolver
Updated on September 18, 2022Comments
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CuriousPuzzleSolver over 1 year
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/bus
and/sys/devices/platform/serial8250.0
and so on in case that is useful. The files/dev/console
,/dev/ttyS0
,/dev/tty
all have read and write permissions. Runninggetty -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::respawn:-/bin/sh
to
inittab
makes busybox give a shell prompt ... but again, the serial console won't take input.dmesg reports
Kernel command line: root=/dev/ram rw init=/init console=ttyS0,115200
and
stty
givesspeed 38400 baud; line=0;
along with a bunch of unimportant looking settings,
stty -a -F /dev/ttyS0
givesspeed 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.-
kurtm over 10 yearsSo this is special-purpose hardware that runs Linux as its firmware? They may have changed a hardware setting to prevent reading the input. Would a
stty -a
(lists all stty settings) give us more clues? Perhaps the kernel boot string specifies some different options now?
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CuriousPuzzleSolver over 12 yearsSame as before, it makes a login prompt appear on the serial console, but I can't give it any input. I need to somehow enable input on /dev/console or something.