How can I make the baud rate be configured automatically?

corone · 11-02-2010, 09:19 PM

Hi,
The /etc/inittab file is configured as the following.

Code:

# vi /etc/inittab
/sbin/getty -l /bin/login /dev/ttyS0 9600 vt100

It always makes the baud rate 9600.
How can I make the baud rate be configured automatically according to the terminal's baud rate? Can I?

neonsignal · 11-02-2010, 10:52 PM

The majority of dumb terminals don't have any protocol for automatic baud rate negotiation.

corone · 11-02-2010, 11:18 PM

Oh, sorry!

Not according to the terminal's baud rate, but according to the baud rate which is configured in the bootloader automatically.
Then, is it possible?

neonsignal · 11-03-2010, 12:24 AM

Quote:

Originally Posted by corone

Not according to the terminal's baud rate, but according to the baud rate which is configured in the bootloader automatically.

It is possible, though perhaps not trivial. For example, you could write a wrapper program in C to replace getty in the /etc/inittab. The wrapper would grab the baud rate from the bootloader configuration, and then invoke the normal getty using execve.

corone · 11-03-2010, 03:51 AM

Thank you for your answer.

What I wanted to know was how to grab the baud rate from the bootloader configuration.

neonsignal · 11-03-2010, 06:39 AM

Quote:

Originally Posted by corone

What I wanted to know was how to grab the baud rate from the bootloader configuration.

Which bootloader are you using? grub2?

frieza · 11-03-2010, 01:47 PM

first of all, what kind of terminal are you using?

I have a WYSE 150 running on /dev/ttyS0 on my machine at 19200. The WYSE terminal's firmware provides a nice menu based configuration for setting the baud rate in it's nvram.

Some older terminals have DIP switches for setting their baud rates.

In short, it is either going to be trial and error to match the entry in /etc/inittab with the baud rate of your device, or a trip to the manual of the terminal if you have it.