Debufs on fstab, go back to tty login to have job control, prepare target makefile for multiple progs

rootfs_overlay/debugfs.sh

@@ -1,6 +1,8 @@
 #!/bin/sh
 set -ex
 mkdir -p /debugfs
+# We also added a fstab entry that mounts this under /sys/kernel/debug autmoatically.
+# That is the most common place to mount it.
 mount -t debugfs none /debugfs
 insmod /debugfs.ko
 cd /debugfs/kernel_module_cheat