Steve Bellovin wrote:
> 
> I asked this question a couple of years ago but didn't pursue it.  I
> now have a more urgent need for an answer:  how do I build a bootable,
> *non-install* NetBSD CD for i386?
> 
> Specifically, I want to put a file system on a CD, plus a boot block
> that will load the kernel from that CD, and run it, multi-user.  I want
> X, I want /usr/pkg, I want amd -- I want a running NetBSD system that I
> can use on a machine that has nothing but Windows on its hard drives.
> 
> The instructions at http://www.netbsd.org/Documentation/bootcd.html
> say to use boot-big, but that always dumps me into sysinst, which isn't
> what I want.  When I asked a couple of years ago, someone suggested
> putting 'root on cd0a' in my config file; I did that, but it didn't do
> what I wanted.
> 
> There are other interesting challenges, such as what to do about applications
> that absolutely demand a writable file system.  I may play around with
> mount_union (or mount_null or mount_overlay, as soon as I understand
> the differences between the three....) to overlay / (or at least /usr)
> with an mfs file system very early in the boot process.  But I need
> to get CD booting working first.
> 
> I tried mkisofs with biosboot.sym, but it complained that it was the
> wrong size.  Could I use vnd to mount a .iso file and then use
> installboot on it?
>
> I'm sure that someone has done this before; it's a fairly obvious thing
> to want to do.  But I haven't figured out how to make it work.

This seems to explain how it works:

http://www.phoenix.com/resources/specs-cdrom.pdf

I think you need to replace the kernel specified in here:

src/distrib/i386/floppies/bootfloppy-big/Makefile

Haven't done this yet, was just starting to try and figure it out...

-Neil