VK3SMB

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=====Update the kernel=====
Download the kernel update code from mdrfr and run the script:
<code>wget http://builder.mdrjr.net/tools/kernel-update.sh
chmod +x kernel-update.sh
sudo ./kernel-update.sh</code>

Reboot the Odroid:
<code>reboot</code>

=====Kernel Source=====
get the kernel source from the github.  You need to run the command straight after updating the kernel so the kernel and the source match:
<code>wget https://github.com/hardkernel/linux/archive/odroid-3.8.y.zip</code>

=====Configuring, Compiling and Installing the Kernel=====
{{ :odroid-kernel-1.png?direct&400 |}}
{{ :odroid-kernel2.png?direct&400 |}}

Update the software repositories:
<code>yum update</code>

Install the following software
<code>yum install -y gcc gcc-c++ make openssl-devel newt-devel ncurses-devel 
libtermcap-devel libxml2-devel perl curl curl-devel lzop
zlib-devel unixODBC-devel libtool </code>

Unzip the Kernel Source then configure it:
<code>unzip odroid-3.8.y.zip
cd linux-odroid-3.8.y
cp arch/arm/configs/odroidu_defconfig ~/linux-odroid-3.8.y/.config</code>
To enable OSS sound card support and the correct /dev drivers, we need to re-compile the kernel with certain options.

<code>make menuconfig</code>

Scroll down the list and go to Device Drivers, then Sound card support.  

You will be presented with the first screen on the right, set the ALSA option to a module (press <M>).

Press [ENTER].  Then enable all the OSS modules you see to make your screen look like the second image.  

When you exit to the first screen, you will see a an option for Preclaim OSS device numbers.  Make sure this is selected with a [*].

Take notice of the Kernel version at the top of the screen

Exit out then save the configuration.

Then build the kernel:
<code>make
make modules
make modules_install
make zImage</code>

Now install the kernel:
<code>mv /boot/uboot/zImage /boot/uboot/zImage.prev
mv arch/arm/boot/zImage /boot/uboot/zImage
</code>

Now reboot
<code>reboot</code>

If all is good, it will reboot back into a login prompt.

====Creating Kernel Scripts====
Create the scripts needed to compile software.
<code>make scripts</code>

====Installing a watchdog====
As all my embedded thingy's are supposed to run unattended without any user interaction, possibly for months, it is probabily a good idea to install a watchdog in the kernel.

The watchdog will reboot the droid (and pi) if the watchdog file is not written to for a period of time.

===Install the watchdog===
go back into the kernel compile folder and make the menu:
<code>make menuconfig</code>

  * Scroll down the list to ''Device Drivers'', press [Enter], 
  * then down to ''Watchdog Timer Support''.  
  * Press the space bar to enable it with a ''*''. 
  * Then press [Enter] to go into the sub menu.
  * Press the space bar on  ''Disable watchdog shutdown on close'', and
  * Software watchdog

Exit back out of the menu.

Make the Kernel as described above and install the new zImage.

Reboot

===Keep the watchdog alive===
In order to stop the watchdog from rebooting the Odroid, we need to write a simple program to 'ping' the watchdog device so it knows the device is still alive.  That program then needs to be run at boot:
<code>nano ~/watchdog.c</code>

Enter the following into nano:
<codee>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>

int main(void)
{
	int fd = open("/dev/watchdog", O_WRONLY);
	int ret = 0;
	if (fd == -1) {
		perror("watchdog");
		exit(EXIT_FAILURE);
	}
	while (1) {
		ret = write(fd, "\0", 1);
		if (ret != 1) {
			ret = -1;
			break;
		}
		sleep(10);
	}
	close(fd);
	return ret;
}
</code>

Save the file, then we have to compile it:
<code>gcc watchdog.c -o watchdog</code>

Now that the program has been compiled, we need to install it into the crontab so it will run at power up.

<code>crontab -e</code>
Enter the following into a new crontab line:
<code>
@reboot /root/watchdog >/dev/null &</code>

By doing all this, the watchdog is hard coded to the kernel and cannot be uninstalled by accident.  The only way to remove the watchdog is to re-compile the kernel without it.

This should mean the odroid is unstoppable on a hill-top or similar place.

You can now go onto building the [[odroid_repeater_controller|Odroid Repeater Controller]]
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