mkbe2gbf

#!/bin/sh
# mkbe2gbf: make bare ext2 grub boot floppy
# by Dan Kegel, http://kegel.com, Oct 2003
# Released under GPL


if test $# != 4; then
    echo "Script to demonstrate creating a bootable floppy image using GRUB and genext2fs 
without root."
    echo "Normally, one uses an initramdisk when booting from floppy, so this script is 
mostly for fun."
    echo "Usage:"
    echo "  mkbe2gbf directory-to-pickle desired-output-file floppy-size-in-kb 
path-to-grub-files"
    echo "Note: genext2fs and grub must be on the PATH,"
    echo "and the kernel should be in /boot/bzImage, and have been compiled with EXT2 and 
without INITRD."
    exit 1
fi


DIR=$1; shift
IMAGE=$1; shift
SIZE=$1; shift
GRUBDIR=$1; shift


TMPDIR=/tmp/mkboot.dir.$$
TMPDEVLIST=/tmp/mkboot.devlist.$$


if test ! -f $GRUBDIR/stage1; then
   echo "Directory $GRUBDIR does not contain file stage1.  Please specify correct path to 
GRUB files."
   exit 1
fi


if ! mkdir $TMPDIR; then
   echo "Failed to create temporary directory $TMPDIR!"
   exit 1
fi

set -x -e


# List devices genext2fs should create.
# This generic set of devices should do for most people; more can be created after boot if needed.
# I bet you could get by with a lot less.
# The format is for the newer genext2fs, i.e.
# http://ftp.debian.org/debian/pool/main/g/genext2fs/genext2fs-1.3.orig.tar.gz as patched by
# http://www.uclibc.org/cgi-bin/cvsweb/buildroot/sources/genext2fs.patch
# (See also http://groups.google.com/groups?selm=ucy95yoxrv.fsf%40habanero.picante.com for alternate approach)
# <path>      <type> <mode>   <uid>   <gid>   <major> <minor> <start> <inc>   <count>
cat > $TMPDEVLIST << _EOF_
/dev/ram0	b	640	0	0	1	0
/dev/mem	c	640	0	0	1	1
/dev/kmem	c	640	0	0	1	2
/dev/null	c	640	0	0	1	3
/dev/zero	c	640	0	0	1	5
/dev/random	c	640	0	0	1	8
/dev/urandom	c	640	0	0	1	9
/dev/ttyS0	c	640	0	0	4	64
/dev/console	c	640	0	0	5	1
/dev/ptmx	c	640	0	0	5	2
/dev/pts/0	c	640	0	0	136	0
_EOF_


# Copy input directory to temporary directory and add grub files
(cd $DIR; find . -print0 | cpio -0pmd $TMPDIR)
mkdir -p $TMPDIR/dev
mkdir -p $TMPDIR/dev/pts
mkdir -p $TMPDIR/boot/grub
test -f $TMPDIR/boot/grub/stage1 || cp $GRUBDIR/stage1 $TMPDIR/boot/grub
test -f $TMPDIR/boot/grub/stage2 || cp $GRUBDIR/stage2 $TMPDIR/boot/grub


# This section's a bit silly; it just creates the demo grub boot menu.
if test ! -f $TMPDIR/boot/grub/grub.conf; then
   if test ! -f $TMPDIR/kernel; then
        echo "Can't find kernel."
        exit 1
   fi
   # Note: root=fd0 fails, it thinks it's a hex number, must use /dev/fd0!
   # OK, this is silly, nobody really uses a floppy as a root device, but hey, it's neat you can.
   cat > $TMPDIR/boot/grub/grub.conf <<_EOF_
title   hOp
root    (fd0)
kernel  /kernel
_EOF_
   # grub actually reads menu.lst, not grub.conf
   ln -s grub.conf $TMPDIR/boot/grub/menu.lst
fi


# Create the image and populate it using genext2fs
# Don't reserve any blocks for the superuser.
genext2fs -r 0 -d $TMPDIR -b $SIZE $IMAGE


# FIXME: use $GRUBDIR/grub ?  We want one that runs on the build machine, not the target...
/sbin/grub --device-map=/dev/null <<_EOF_
device (fd0) $IMAGE
root (fd0)
setup (fd0)
_EOF_

rm -rf $TMPDIR $TMPDEVLIST