Subject: Re: Problems with serial console redirection
To: David Francheski <>
From: Pavel Cahyna <>
List: tech-kern
Date: 01/17/2003 12:19:50
> # This option allows you to force a serial console at the specified
> # I/O address.   see console(4) for details.
> options    CONSDEVNAME="\"com\"",CONADDR=0x3f8,CONSPEED=57600
> #       you don't want the option below ON if you are using the
> #       serial console option of the new boot strap code.
> options    CONS_OVERRIDE   # Always use above! independent of boot info
Maybe this is not even necessary. The bootloader has a command to switch
to serial conslole, and then it should pass this info to the kernel. See
boot(8). There is even a modified bootloader (/usr/mdec/biosboot_com.sym
or something like that) which has serial console as the default.
(I haven't actually tried this on an i386).

But this is probably not the cause of your problem.

> I have tried different tweaks to the wscons.conf but without much luck.
Wscons doesn't have any importance here, it manages console on
graphiccards (vga), not on serial lines.

> What happens on boot of the generated kernel is that the console
> messages 
> actually do get redirected to the serial connect (I am connecting
> through a 
> Console Management station which takes the serial port and maps the 
> console/keyboard over) and the messages seem to be echoed out properly.
> The last messages I get on the redirected screen are:
>   Starting sshd
>   Starting inetd
>   Starting cron
>  <a printout of the current date/time >
> then the connection goes dead and all I get are garbage characters on
> the 
> screen, I am expecting that this must be the time wscons takes over for
> the 

Surely not wscons - it doesn't care about serial lines. It's probably
getty. Look at your /etc/ttys, you probably have a line like
console "/usr/libexec/getty std.9600" vt100 on secure

std.9600 is a description of terminal and it's an index into
/etc/gettytab. You will probably replace it by std.57600 or whatever is
appropriate for your serial line.

There also may be lines for your serial ports, (tty00, tty01 etc). The
line corresponding to the port you use should be commented or have the
"off" keyword, because /dev/console is an alias for this port and you
would have two gettys on it, which is IMHO not good (although I haven't
tried it.)

Hope this helps.
bye	Pavel