Booting multiple choice, and pause to read bootup info

[J. Porter Clark]

On Tue, Jun 29, 2010 at 04:00:21AM -0500, Robert Bonomi wrote:
> >
> > 1. I'd like to be able to expand the list of choices in the
> > boot menu (the menu with single user mode, safe mode, etc.) to
> > include booting in any of several different environments, e.g.,
> > home wired, home wireless, work wired, work wireless.  Hacking
> > the FORTH code isn't entirely out of the question, but before
> > I even try it, I need to know how I could tell the system to
> > switch among different rc.conf files (if that's even possible)
> > from the loader.  Offhand, I don't see a mechanism for doing so.
> > Cleverer ideas welcome.
> 
> There's no 'built in' mechanism.
> 
> There's no "easy" way.
> 
> Closest thing -to- an 'easy way' is to set an environment variable
> _very_early_ in the boot process, and then use it to 'conditionalize'
> (how -that- for an ugly word? :) the setting of various stuff in rc.conf
> e.g.:
>         case $USER_ENV in
> 	home) USE_LDAP="no"
> 	      ;;
> 	work) USE_LDAP="yes"
> 	      ;;
> 	esac

I wasn't aware that setting an environment variable inside the
loader would propagate into the rc.conf environment.  Is this
so?

> > 2. Usually, when the system boots, there are several lines
> > showing the kernel and various modules loading, possibly with
> > diagnostics.  Is there a way to pause after that stage, so that
> > those lines can be read?  Or is there any way to retrieve them
> > after the system has booted?
> 
> I havven't tried it on FBSD, in a long time, but most PC "BSDs" will pause 
> the boot screen if you hit [CTL-S], or the PAUSE key.
> 
> Alternatively, does dmesg(8), used 'reasonably soon' after booting,  give
> you what you want?
> 
> Note: a typical installation will have syslogd putting _most_ of those 
> messsages in the system log file, too.

Y'all are way off base here: it's not the lines from the kernel
itself booting, it's the lines *before* that, where the loader
is loading the kernel and various modules.  Occasionally, I
see error messages here, but they vanish pretty quickly on my
machines, too fast to be caught reliably with CTL-S, SCROLL
LOCK, etc.  I could set up a serial console, but it seems like a
lot of work just to see these messages.

-- 
J. Porter Clark      <jpc at porterclark.com>