Bug#489006: #489006 debian-installer: After grub software raid installation, machine fails to boot with first drive removed or blanked

[Miguel Figueiredo <elmig@debianpt.org>]

Hi,

i've made a (very) slight modification to Raphael's patch so it can be applied 
against current grub-installer code.

So here it goes for review.


-- 
Melhores cumprimentos/Best regards,

Miguel Figueiredo
http://www.DebianPT.org

diff --git a/grub-installer b/grub-installer
index fe33471..784dc41 100755
--- a/grub-installer
+++ b/grub-installer
@@ -223,10 +223,14 @@ esac
 rootfs_nodevfs=$(mapdevfs $rootfs)
 bootfs_nodevfs=$(mapdevfs $bootfs)
 prefix=$(device_to_disk "$bootfs")
+boot_on_md=""
 
 case $prefix in
     /dev/md)
 	disc_offered_devfs="$bootfs"
+	grub_package="grub-pc"
+	boot_on_md="1"
+	log "Boot partition $bootfs is on a RAID device, use grub-pc and (mdX) device for installation."
 	;;
     /dev/mapper)
 	disc_offered_devfs="$bootfs"
@@ -537,11 +541,18 @@ fi
 
 # Try to avoid using (hd0) as a boot device name.  Something which can be
 # turned into a stable by-id name is better.
-default_bootdev_os="$($chroot $ROOT grub-mkdevicemap --no-floppy -m - | head -n1 | cut -f2)"
-if [ "$default_bootdev_os" ]; then
-	default_bootdev="$($chroot $ROOT readlink -f "$default_bootdev_os")"
+# Use md0 for RAID instead of sda as it installs on every drive. See #489006.
+if [ -n "$boot_on_md" ]; then
+	if [ ! -e $ROOT/boot/grub/device.map ]; then
+		$chroot $ROOT grub-mkdevicemap
+	fi
+	bootdev=$($chroot $ROOT grub-probe -t drive -d $bootfs)
 else
-	default_bootdev="(hd0)"
+	default_bootdev_os="$($chroot $ROOT grub-mkdevicemap --no-floppy -m - | head -n1 | cut -f2)"
+	if [ "$default_bootdev_os" ]; then
+		default_bootdev="$($chroot $ROOT readlink -f "$default_bootdev_os")"
+	else
+		default_bootdev="(hd0)"
 fi
 
 # Set a sensible default boot device, so that we aren't installing GRUB to
@@ -586,7 +597,14 @@ while : ; do
 		fi
 		db_get $q
 		if [ "$RET" = true ]; then
-			bootdev="$default_bootdev"
+			if [ -n "$boot_on_md" ]; then
+				if [ ! -e $ROOT/boot/grub/device.map ]; then
+					$chroot $ROOT grub-mkdevicemap
+				fi
+				bootdev=$($chroot $ROOT grub-probe -t drive -d $bootfs)
+			else
+				bootdev="$default_bootdev"
+			fi
 			break
 		else
 			# Exit to menu if /boot is on SATA RAID/multipath; we