Expose the internal storage partition as an USB mass storage block

build_rootfs.sh

@@ -75,8 +75,11 @@ config_rootfs() {
   mkdir ./rootfs/mnt/onboard
   mkdir ./rootfs/mnt/external
   cp files/fstab rootfs/etc/
-  chown root:root rootfs/etc/fstab
+  cp files/rc.local rootfs/etc/
+
+  chown root:root rootfs/etc/fstab rootfs/etc/rc.local
   chmod 644 rootfs/etc/fstab
+  chmod 755 rootfs/etc/rc.local
   
   echo "Configuration done."
 }

files/rc.local

@@ -0,0 +1,6 @@
+#!/bin/sh -e
+
+depmod -a
+modprobe g_file_storage file=/dev/mmcblk0p3
+
+exit 0