Chris Marget on 10 Apr 2006 15:13:41 -0000

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Re: [PLUG] Linux Serial console

> > I'd like to
> > have a serial console available on several linux machines, is this an easy
> > thing to accomplish?  Ideally we'd even have bios access (is this possible).

> Bios stuff depends on make/model of your motherboard, some support it,
> some do not.

This feature is usually called "serial console redirection" or somesuch.
It's a great feature, usually reserved for expensive server-ish

When available, it's great.

Other server-ish systems have complete standalone computers for
administration.  Compaq iLo is an example of this.  These allow you to
turn power on/off and fiddle with console features remotely, sometimes
through serial, other times through Ethernet.

> Otherwise you just need a serial console switch.

Well, a terminal server like is only useful if you've got something to
connect to.

In the absense of special features you need to get your linux system to
output to the serial port.

It's been years since I've fiddled with it, but basically you want two

1) Bootloader prompt to appear on the serial.

   With hardware solutions described above, this is handled through
   hardware.  With normal systems, you need to tell lilo/grub to do it.
   Something like 'serial=0,9600n8' works for lilo.

   I think this will cause all the kernel bootup messages to go to
   serial as well.

2) Login prompt to appear on the serial.

   I've accomplished this by running a mingetty or agetty via init.


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