View source for XELK-AN-006: Modify u-boot environment from userspace

== u-boot environment access example ==
* display the <code>ipaddr</code> and <code>bootfile</code> environment variables:
<pre class="board-terminal">
root@imx6qxelk:~# fw_printenv ipaddr bootfile
ipaddr=192.168.0.90
bootfile=axel/linux/xelk-3.0.7_uImage
root@imx6qxelk:~#
</pre>

=== Wrong configuration file ===
If some parameters are not correctly configured on the ''fw_env.config'' file, the utilities displays an error message:

<pre>
Warning: Bad CRC, using default environment
</pre>

It is possible to detect this situation using the return code of <code>fw_printenv</code>:

* ''fw_env.config'' correct file
<pre class="board-terminal">
root@imx6qxelk:~# fw_printenv ipaddr
ipaddr=192.168.0.90
root@imx6qxelk:~# echo $?
0
root@imx6qxelk:~#
</pre>
* '''wrong''' ''fw_env.config'' file
<pre class="board-terminal">
root@imx6qxelk:~# fw_printenv ipaddr
Warning: Bad CRC, using default environment
## Error: "ipaddr" not defined
root@imx6qxelk:~# echo $?
1
root@imx6qxelk:~#
</pre>