[FE training-materials-updates] Document U-boot's editenv command and suggest to use it

[Michael Opdenacker]

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

On branch  : master
Link       : http://git.free-electrons.com/training-materials/commit/?id=13424cb83f9bb49338389d37609129d3fe209a8f

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

commit 13424cb83f9bb49338389d37609129d3fe209a8f
Author: Michael Opdenacker <michael.opdenacker at free-electrons.com>
Date:   Mon Feb 3 06:02:00 2014 +0100

    Document U-boot's editenv command and suggest to use it
    
    Signed-off-by: Michael Opdenacker <michael.opdenacker at free-electrons.com>


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

13424cb83f9bb49338389d37609129d3fe209a8f
 labs/android-new-board/android-new-board.tex       |    7 +++++
 labs/sysdev-tinysystem/sysdev-tinysystem.tex       |    3 ++
 .../sysdev-bootloaders-u-boot.tex                  |   33 +++++++++++++-------
 3 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/labs/android-new-board/android-new-board.tex b/labs/android-new-board/android-new-board.tex
index 24efd5a..042a792 100644
--- a/labs/android-new-board/android-new-board.tex
+++ b/labs/android-new-board/android-new-board.tex
@@ -321,6 +321,13 @@ setenv bootargs console=ttyO0,115200 root=/dev/nfs ip=192.168.0.100
 Of course, you need to adapt the IP addresses to your exact network
 setup. Save the environment variables (with \code{saveenv}).
 
+If you later want to make changes to this setting, you can type the
+below command in U-boot:
+
+\begin{verbatim}
+editenv bootargs
+\end{verbatim}
+
 Now, boot your system. The kernel should be able to mount the root
 filesystem over NFS:
 
diff --git a/labs/sysdev-tinysystem/sysdev-tinysystem.tex b/labs/sysdev-tinysystem/sysdev-tinysystem.tex
index 53d031c..20df0b4 100644
--- a/labs/sysdev-tinysystem/sysdev-tinysystem.tex
+++ b/labs/sysdev-tinysystem/sysdev-tinysystem.tex
@@ -93,6 +93,9 @@ setenv bootargs console=ttyO2,115200 root=/dev/nfs ip=192.168.0.100
 Of course, you need to adapt the IP addresses to your exact network
 setup. Save the environment variables (with \code{saveenv}).
 
+You will later need to make changes to the \code{bootargs} value.
+Don't forget you can do this with the \code{editenv} command.
+
 Now, boot your system. The kernel should be able to mount the root
 filesystem over NFS:
 
diff --git a/slides/sysdev-bootloaders-u-boot/sysdev-bootloaders-u-boot.tex b/slides/sysdev-bootloaders-u-boot/sysdev-bootloaders-u-boot.tex
index 2fb98d4..5540434 100644
--- a/slides/sysdev-bootloaders-u-boot/sysdev-bootloaders-u-boot.tex
+++ b/slides/sysdev-bootloaders-u-boot/sysdev-bootloaders-u-boot.tex
@@ -231,27 +231,36 @@ U-Boot 2013.04 (May 29 2013 - 10:30:21)
 \end{frame}
 
 \begin{frame}
-  \frametitle{Environment variables commands}
+  \frametitle{Environment variables commands (1)}
   \begin{itemize}
   \item U-Boot can be configured through environment variables, which
     affect the behavior of the different commands.
   \item Environment variables are loaded from flash to RAM at U-Boot
     startup, can be modified and saved back to flash for persistence
-  \item There is a dedicated location in flash to store U-Boot
-    environment, defined in the board configuration file
-  \item Commands to manipulate environment variables:
-    \begin{itemize}
-    \item \code{printenv}, shows all variables
-    \item \code{printenv <variable-name>}, shows the value of one variable
-    \item \code{setenv <variable-name> <variable-value>}, changes the
-      value of a variable, only in RAM
-    \item \code{saveenv}, saves the current state of the environment to flash
-    \end{itemize}
+  \item There is a dedicated location in flash (or in MMC storage)
+    to store the U-Boot environment, defined in the board configuration file
+  \end{itemize}
+\end{frame}
+
+\begin{frame}
+  \frametitle{Environment variables commands (2)}
+  Commands to manipulate environment variables:
+  \begin{itemize}
+    \item \code{printenv}\\
+      Shows all variables
+    \item \code{printenv <variable-name>}\\
+      Shows the value of a variable
+    \item \code{setenv <variable-name> <variable-value>}\\
+      Changes the value of a variable, only in RAM
+    \item \code{editenv <variable-name>}\\
+      Edits the value of a variable, only in RAM
+    \item \code{saveenv}\\
+      Saves the current state of the environment to flash
   \end{itemize}
 \end{frame}
 
 \begin{frame}[fragile]
-\frametitle{Environment variables commands (2)}
+\frametitle{Environment variables commands - Example}
 \begin{verbatim}
 u-boot # printenv
 baudrate=19200