login prompt not reading keyboard entries properly in serial port
 

In my embedded Linux (2.6) I am trying to enable login in serial port, so that after booting I should get the login prompt. I am using ttyS1 and in the /etc/inittab file I added this line to enable the login.

respawn:/bin/login < /dev/ttyS1 > /dev/ttyS1 2> /dev/ttyS1

Now I am gettig the login prompt but while typing the user name the login screen displays only alternate characters in the username (eg: if I type guest the screen displays ust), and unable to login also.

Instead of /bin/login tried using /sbin/getty, here also the scenario is same. With getty we can give the baud rate as a parameter, so I tried all standard baud rates but nothing worked.

minicom is my serial port interface. What will be the issue ? Need help

I would read the docs under linux/Documentation for your 2.6 kernel regarding kernel parameters. Which login and which getty version? There are more than one in the world.

Thanks for the response, I am using the login and getty commands which are coming as part of BusyBox v1.18.4

On a typical x86 using init, inittab would be

co:2345:respawn:/sbin/getty -L ttyS1 9600 vt100

You would need to configure minicom serial parameters for 9600, no parity, 8 bits, 1 stop bit and the port used on the computer connected to the SBC. Without knowing anything about your embedded device it is difficult to determine the problem.

Still trying to solve the issue. The minicom serial port parameters are, no parity, 8 bits, 1 stop bit and the my default baud rate is 57600.
The board is using the second UART so in the embedded Linux the serial port is /dev/ttyS1.
I cross compiled the latest version of busybox and tested, then also the issue is same. Doing further debugging I found that the login is using fgets for reading the username. So I created a small application and invoked it from the inittab (temporarily removed the login)

The application and its outputs

int main()
{
char str[25];
printf("Enter something:");
if(fgets (str, 25, stdin))
{
printf("String Read:");
puts(str);
}
return(0);
}

Now after booting, the above application start respawning
Enter something: guest
gString Read: uest

Enter something: guest
String Read: guest

Enter something: guest
gString Read: uest

Enter something: guest
String Read: guest

Enter something: (PRESSED ENTER KEY TWO TIMES)

/bin/sh: gg: not found
/ #

In the above example we can see that sometimes the first character is not going to the str[] buffer, it is read by the shell. After this if I give two enters continuously it shows
/bin/sh: gg: not found (gg is the two characters which are not read by the str[]).
This scenario is not only for the first characters, happening for intermediate characters also.
If I do ssh to this Linux and run this application, this reads full characters with out any drop.
Please help

Which 2.6 kernel? Maybe you are using a broken kernel.