[FE training-materials-updates] Tell to use the radio user to test the binary, otherwise, it will just work

[Maxime Ripard]

Repository : git://git.free-electrons.com/training-materials.git

On branch  : master
Link       : http://git.free-electrons.com/training-materials/commit/?id=63197c674696746f1ddeb65ba173930ad5a5cf94

>---------------------------------------------------------------

commit 63197c674696746f1ddeb65ba173930ad5a5cf94
Author: Maxime Ripard <maxime.ripard at free-electrons.com>
Date:   Fri Mar 22 13:58:41 2013 +0100

    Tell to use the radio user to test the binary, otherwise, it will just
    work
    
    Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>


>---------------------------------------------------------------

63197c674696746f1ddeb65ba173930ad5a5cf94
 labs/android-native-app/android-native-app.tex |   19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/labs/android-native-app/android-native-app.tex b/labs/android-native-app/android-native-app.tex
index 0c98128..5a0e5ed 100644
--- a/labs/android-native-app/android-native-app.tex
+++ b/labs/android-native-app/android-native-app.tex
@@ -23,11 +23,20 @@ application. You should see the launcher move.
 
 \section{Fix the Problems}
 
-However, when you start your tests, you will find that \code{libusb} cannot open
-the usb devices because of restricted permissions. This can be fixed
-through \code{ueventd.rc} files. Add a device-specific \code{ueventd}
-configuration file to your build to make the files under
-\code{/dev/bus/usb/} world readable.
+The permission model of Android is heavily based on user
+permissions. By default, your USB device won't be accessible to
+applications. We didn't see this behaviour because we ran the mlbin
+program as root. To test if the program runs properly, test it as a
+random user on the system.
+
+To do so, you can use the command \code{su}, and you can test with the
+user \code{radio} for example.
+
+When you start your tests, you will find that \code{libusb} cannot
+open the usb devices because of restricted permissions. This can be
+fixed through \code{ueventd.rc} files. Add a device-specific
+\code{ueventd} configuration file to your build to make the files
+under \code{/dev/bus/usb/} world readable.
 
 \paragraph{Warning} The ueventd parser is buggy in Gingerbread and
 doesn't read the \code{androidboot.hardware} parameter. You will have