linuxrc: run the debug shell multiple times, add a hook before switch_root

defaults/initrd.scripts

@@ -1055,6 +1055,7 @@ rundebugshell() {
 	if [ -n "$DEBUG" ]
 	then
 		good_msg 'Starting debug shell as requested by "debug" option.'
+		good_msg "Stopping by: ${1}"
 		do_rundebugshell
 	fi
 }

defaults/linuxrc

@@ -424,7 +424,7 @@ mkdir -p "${NEW_ROOT}"
 CHROOT="${NEW_ROOT}"
 
 # Run debug shell if requested
-rundebugshell
+rundebugshell "before setting up the root filesystem"
 
 if [ "${CDROOT}" = '1' ]
 then
@@ -937,6 +937,9 @@ then
 	bad_msg "ERROR: your real /dev is missing tty1, required for splash"
 fi
 
+# Run debug shell if requested
+rundebugshell "before entering switch_root"
+
 exec /sbin/switch_root -c "/dev/console" "${CHROOT}" "${REAL_INIT:-/sbin/init}" "${INIT_OPTS}"
 
 # If we get here, something bad has happened