[vox-tech] complete serial console success! (was: Re: minicom help)

[Ted Deppner]

On Fri, Jan 04, 2002 at 11:07:54AM -0800, Henry House wrote:
> Okay, I finally have it :-). Steps:
>=20
> 6. Reboot and pat yourself on the back if all went according to plan :-).

Excellent work Henry.  A few items that might be gotchas for some.

If you're using lilo, you'll need a recent lilo, else the ctrl-break will
'lock up' lilo.  potato's won't work, woody's lilo will.  You'll still
boot up fine, but won't be able to type in alternate boot commands like
"single" or "emergency".

Second, currently potato using sysvinit has a bug in the tty port handling
where CREAD is unset [1].  This means if you try a "single" or "emergency"
bootup, OR if your on boot fsck's fail, you won't be able to login.

You can add CREAD to the sysvinit program yourself (I can produce a patch
if desired), upgrade to sysvinit from woody, or create a sulogin wrapper
that sets CREAD yourself [2].

Third, you'll want to remove /etc/ioctl.save in most cases the first
serial boot, since it is the default TTY IOCTL sysvinit uses if present,
and may have a 38400 baud rate from your tty0 boot in it.

There is a linux serial console howto that mentions many of these items...
it might be another good resource to link too.


[1]
It's not really a sysvinit but, but sysvinit is the right place to fix it.
Early in 2.4.x the kernel changed the default tty settings, and sysvinit
needs to be updated to work properly with kernels 2.4.3 or so and up.


[2]
# mv /sbin/sulogin /sbin/sulogin.elf
# cat > /sbin/sulogin
#! /bin/sh

/bin/stty CREAD
exec /sbin/sulogin.elf "$@"
<ctrl-d>
# chmod 755 /sbin/sulogin
# # test it!
# /sbin/sulogin /dev/tty10
# # see if you can login to console at F-10
# note that ugprading sysvinit will overwrite your shell script

--=20
Ted Deppner
http://www.psyber.com/~ted/