mkdir /dev/usb-ffs/adb 0770 shell shell
mount functionfs adb /dev/usb-ffs/adb uid=2000,gid=2000
write /sys/class/android_usb/android0/f_ffs/aliases adb
+
+ setprop sys.usb.ffs.aio_compat 1
on post-fs-data
chown system system /sys/class/android_usb/android0/f_mass_storage/lun/file