Boot from CD (Digest, Vol 156, Issue 6 0, msg 12)

[Keith McKenzie]

Date: Mon, 13 Nov 2006 21:49
From: Nils Vogels <nivo+sender+6075ff at is-root.com>
Subject: Re: Boot from CD (this time in ASCII :) )

a.brancatelli.mail at sara.it wrote on 13-11-2006 16:28:
> Now my question is this: how do the kernel know where to search the fstab
> (considered that the fstab says where to find the /etc)? I mean: I suppose
> I have to put on the CDROM an exact /etc/fstab for that installation?? Or
> this could be avoided? Also because I may need to edit the fstab for the
> machine without having to reburn the CD? so what? Or maybe the kernel can
> actually just be read from the CD and then everything else from the ( SAN 
> |
> local ) drive? Am I missing something?
>
Have a look at the following manpages:

boot(8)
loader(8)

This explains the FreeBSD startup system.

In short, you tell the loader which kernel to boot, and you tell the
kernel where the root filesystem is. The root fileystem is considered to
contain instructions on how to proceed from there.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I agree with taking a look at the man pages, but I think what you are 
looking for is creating the actual CD image - what I have managed to do, 
using FreeSBIE 1.1 as a base, is to create my own image and burn it to disk. 
the following is the incantation:-

mkisofs -b boot/cdboot -no-emul-boot -c boot/cat -J -r -ldots -l -L -o 
my.iso <directory for image>

Note 1: cdboot is a file in the boot directory
Note 2: fstab =>  /dev/acd0    /    cd9660    ro    0    0

You can change the entry in fstab to boot whatever partition you like, as 
long as it is /

(I am not an expert, but it worked for me - I am still experimenting.)

HTH
Keith