Subject: Re: Console Redirection After Boot
To: Matt Domsch <>
From: Brian A. Seklecki <>
List: netbsd-users
Date: 11/03/2006 13:27:58
On Wed, 2006-11-01 at 09:08 -0600, Matt Domsch wrote:
> On Wed, Nov 01, 2006 at 10:37:01AM -0400, eclark wrote:
> > there any way to force serial console redirection in the kernel, so I can log 
> > boot sequences? It gets a bit old having to continuously reboot to stare at 
> > scrolling messages when you are trying to do kernel testing.

Just for the record, I just tested:

- An Intel Server Motherboard SE7520*
- A Dell PE2950
- An Axiomtek SBC83672

All have Phoenix BIOS.  All exhibit the same behavior.  I/O to the
console does not get redirected to serial _unless_ it was sent there via
a BIOS call.  Ah la, DOS.

The only options are:

- Write a framebuffer driver for the kernel that uses BIOS calls (_not
  likely_, and for which there would most presumably be no terminal
  disciplines capable of running sysint/sysinstall)

- Convince hardware vendors like Dell/Intel to implement a more Real
  Weasel-like console redirection system (not likely)

- Convince Dell not to re-write the ActiveX applet that is the DRAC5
  interface in something slight more portable, such as...oh, Java.

- During emergency scenarios like DRP deployment, have a Windows system

- Buy an OpenBoot enabled platform. =p J/K

#3 seems most logical.  Well at least now I understand the problem in
its entirely.  Thanks all.


> That's easy.
> 1) Disable (or really, don't enable) console redirection in BIOS SETUP.
> 2) Put on the kernel command line:  console=ttyS0,115200 console=tty0
> We do 99% of our kernel debugging this way.
Brian A. Seklecki <>
Collaborative Fusion, Inc.