buildroot/docs/README.diskimage

# Sample for i386 to create a 6MB disk-image

# create an image file
dd if=/dev/zero bs=512 count=$((6*1024*1024/512)) of=img
# create a partition (optional)
echo -e "n\np\n1\n\nw\n" | \
  ~/src/busybox/busybox fdisk -C 16065 -H 255 -S 63 ./img
# as root, associate the image with a look-device:
# The offset of 512 comes from the the layout of the image. See
# ~/src/busybox/busybox fdisk -C 16065 -H 255 -S 63 -l ./img for the start
# block and multiply this with the block size (==512).
~/src/busybox/busybox losetup -o 512 /dev/loop/0 /path/to/the/img
# create some filesystem on it, for example ext2
mkfs.ext2 -m0 -Lslash /dev/loop/0
# mount it and copy your stuff to it
~/src/busybox/busybox mount -oloop,rw /dev/loop/0 /media/l0
~/src/busybox/busybox mkdir -p /media/l0/boot/grub
~/src/busybox/busybox cp -a project_build_i386/root/boot/grub/stage? /media/l0/boot/grub/
~/src/busybox/busybox cp -a project_build_i386/root/boot/bzImage /media/l0/boot/
~/src/busybox/busybox cat > /media/l0/boot/grub/menu.lst <<EOF
title=GNU/Linux
root (hd0,0)
kernel /boot/bzImage
EOF
# finally unmount the dist and disassociate the loopdev
~/src/busybox/busybox umount /media/l0
~/src/busybox/busybox losetup -d /dev/loop/0
# now install grub from the chroot
~/src/busybox/busybox losetup /dev/loop/0 /path/to/the/img
project_build_i386/root/usr/sbin/grub --device-map=/dev/null
device (hd0) img
geometry (hd0) 16065 255 63
root (hd0,0)
setup (hd0)
quit
# finally boot the thing
/opt/qemu-trunk_ggi-2.2.2/bin/qemu -snapshot -hda img -boot c