Subject: Re: Hardware Console Redirection
To: Andrew Reilly <>
From: Brian A. Seklecki <>
List: netbsd-users
Date: 11/01/2006 01:05:04
> Why is that a problem?  The BIOS doesn't use the console once
> the kernel has booted.

Because it becomes a burden always having to customize your
install/upgrade media/kernels/bootblocks to use redirection. 

Dell knew that; that's why they made the DRAC4 with a virtual VNC-based
console redirection.  Then the bungled it with the DRAC5 when they
re-wrote it to depend on ActiveX.

Also because the hardware vendors could follow the PC Weasel model and
not utilize a serial port visible to the OS.

With NetBSD its just one or two flags to installboot(8) to change the
options, with the only exception being that we seem to lack the ability
to set the com console _speed_ when in *interactive* mode at boot(8) ;
of course it can be set from the installboot(8) flags.

With FreeBSD, you have to jump through a ring of fire to get it to work
right.  You've got three stages of bootblocks to recompile/configure. 
boot.config.  device.hints. etc. etc.  Then the kernel has to be told
in-src, recompiled.  Then the getty.

In either case, forget about sysinst/sysinstall to install off of stock
install media.  All very possible with the Weasel.

You alway have to consider the the 3:30 AM incident where you're
fumbling though a stack of CD-Rs for a Fixit or Live CD and you have to
wonder if you re-mastered the disc with a boot image containing your
custom serial enabled kernel with the right baud and com port (as you
can see below).

> What serial console semantics do the bootblocks get wrong?

None.  I'm just suggesting that for simplicity it would be nice not to
have to make them aware.

> What sort of reset do you need?  I don't really understand the
> question, I'm afraid.  

Reset my attitude I guess >:}  I'm pining for the days of sparc systems
and a unified serial console server.

When TLS says: "Of course; it is a BIOS feature, and NetBSD does not use
the BIOS for console I/O.", I tend to think of Sun how writing to the
OBP firmware console is not dissimilar from the NetBSD kernel output.

It would be nice to think x86 has caught up over the last 15 years.

Anyway, for the record:

The old PC Weasel Console Redirection:

Phoenix BIOS:

NetBSD 2.0 Sysinst:

Bios Summary:


Dell PE750 Console Redirection:

Compare where DRAC VNC (IE6 only) VGA redirected console output
continues and the DRAC5 virtual "COM2" serial redirection halts:

Dell PE2950 Settings (BIOS nicely drawn via Serial/ANSI):