Ensure that MBR jumping to GRUB's core.img code

Previously, bootgrub.mksh took that job but we just resolved it.
New approach based as done on [1] but with copying 440 bytes only
(rather than 446), to keep existing disk identifier in place [2].

[1] http://pete.akeo.ie/2014/05/compiling-and-installing-grub2-for.html
[2] https://en.wikipedia.org/wiki/Master_boot_record#Sector_layout

diff --git a/grml-debootstrap b/grml-debootstrap
index 0feed2a..322c931 100755 (executable)
--- a/grml-debootstrap
+++ b/grml-debootstrap
@@ -1191,8 +1191,9 @@ if [[ -z "${GRUB}" ]] || ! dd if="${GRUB}" bs=512 count=1 2>/dev/null | cat -v |
       cp -a "${MNTPOINT}"/usr/lib/grub/i386-pc "${MNTPOINT}/boot/grub/"
       ;;
   esac
+  dd if="${MNTPOINT}/usr/lib/grub/i386-pc/boot.img" of="${ORIG_TARGET}" conv=notrunc bs=440 count=1
   chroot "${MNTPOINT}" grub-mkimage -O i386-pc -p "(hd0,msdos1)/boot/grub" -o /tmp/core.img biosdisk part_msdos ext2
-  dd if="${MNTPOINT}/tmp/core.img" of="${ORIG_TARGET}" conv=notrunc seek=4
+  dd if="${MNTPOINT}/tmp/core.img" of="${ORIG_TARGET}" conv=notrunc seek=1
   rm -f "${MNTPOINT}/tmp/core.img"
 fi