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Date:      Fri, 10 May 2002 11:09:10 -0700 (PDT)
From:      Gordon Tetlow <gordont@gnf.org>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        Julian Elischer <julian@elischer.org>, Jonathan Mini <mini@freebsd.org>, Michael Smith <msmith@mass.dis.org>, <hackers@freebsd.org>
Subject:   Re: nextboot loader diff
Message-ID:  <Pine.LNX.4.44.0205101100520.27477-100000@smtp.gnf.org>
In-Reply-To: <3CDC01ED.A188796F@mindspring.com>

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On Fri, 10 May 2002, Terry Lambert wrote:

> It's actually just as easy to make boot1 go read it itself, assuming
> boot1 has the ability to read.  It also decouples it somewhat, which
> (IMO) is a good thing.  This is actually the same effect they get from
> using a seperate file, which gets rewritten, rather than hacking "YES"
> vs. "TRY" vs. "NO" in a common .conf file (which makes me incredibly
> nervous, just like Mike's complaint about it).

This is not intended to be used in an "Oh Crap, I just lost a disk and 
need to recover situation". This is to be used in the following situation 
(at least, this is how I envisioned it):

I have machine A co-located far far away with no console access.
I want to put a new kernel on it, but am nervous about what happens if the 
machine doesn't come back up because I botched the new kernel.
I use nextboot to make my new kernel only boot once, in case where the 
machine hangs and needs to be rebooted (maybe I can tell a noc monkey to 
reboot the sucker), it'll then fall back to my known good kernel.

There are some huge assumptions on my part that I should have spelled out 
a bit more in my initial email:

A) you are going to be using nextboot on a consistent filesystem (after
all you rebooted the box, it should (in theory) be a consistent filesystem
when the loader goes and rewrites the /boot/nextboot.conf) B) this wasn't
to do anything more clever than pass a few args to loader for one shot. C)
this was intended to be used by developers who know what they are doing
and would like a little extra security and don't want to have to pay a noc
monkey to try and fix their configuration over the phone. I've done that
waaaay too many times than I care to remember. If this feature was in
there, I could just tell them to reboot the box, and it would come back to 
the kernel that I know was good.

Again, please look at it as a convenience, not something that will save 
your ass. It will happily let you shoot yourself in the foot, but hey so 
will rm(1).

-gordon


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