I’m using the Arietta G25 for a project of mine. Earlier I described how to build a bootloader for the 256MB version of the board.

Today I’m going to describe how to build the kernel for the Arietta G25. I needed ADC support as well as modules for some USB to ethernet adaptors that weren’t included in the kernel image ACME Systems provides.

First off you will need to install the toolchain to build armel binaries. ACME Systems has a page describing how to install the ARM9 toolchain. Here’s the short summary:

$ sudo apt-get install emdebian-archive-keyring libc6-armel-cross libc6-dev-armel-cross binutils-arm-linux-gnueabi gcc-arm-linux-gnueabi g++-arm-linux-gnueabi u-boot-tools libncurses5-dev

Once you have the environment setup it’s time to checkout the kernel and build. This is the Jenkins script I use to build the Arietta G25 kernel:

if [ ! -d "linux-3.14.7" ]; then
wget https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.14.7.tar.xz -O linux-3.14.7.tar.xz
tar xvfJ linux-3.14.7.tar.xz
cd linux-3.14.7
wget http://www.acmesystems.it/www/compile_linux_3_14/acme.patch -O acme.patch
patch -p1 < acme.patch

wget https://watchmysys.com/blog/wp-content/uploads/2014/08/linux-at91.config -O .config
wget https://watchmysys.com/blog/wp-content/uploads/2014/08/arietta_256m_ikconfig.patch -O arietta_256m_ikconfig.patch
patch -p1 < arietta_256m_ikconfig.patch
else
cd linux-3.14.7
fi
make ARCH=arm clean
CPUS=$(cat /proc/cpuinfo | grep -c "processor")

wget https://watchmysys.com/blog/wp-content/uploads/2014/08/acme-arietta-adc.dtb -O arch/arm/boot/dts/acme-arietta.dtb
make -j$CPUS ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- zImage
make modules -j$CPUS ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-
make modules_install INSTALL_MOD_PATH=./modules ARCH=arm
mkdir -p modules/boot
cp arch/arm/boot/zImage modules/boot/
rm linux-3.14.7-arietta.tar.bz2
tar -C modules -cjvf linux-3.14.7-arietta.tar.bz2 lib/ boot/

The above commands are available in a bash/Jenkins script at the bottom of this post.

Installation is fairly simple, you need to mount the sdcard /boot and / partitions on your computer and then run:

tar -C /path/to/sdcard -jxvf linux-3.14.7-arietta.tar.bz2

My kernel configuration includes the Atmel ADC driver as a module (at91_adc) so you can unload/reload it (possibly to save power). It also includes the dm9601 and sr9700 modules for the Davicom DM96xx USB 2.0 10/100M Ethernet Adaptor, which is an inexpensive USB to ethernet adaptor available online (such as this one).

If you want to generate your own dtb (for instance enable PWM instead of the ADC) you can do that at this ACME Systems page.

Build script: linux-at91.sh
Kernel and modules: linux-3.14.7-arietta.tar.bz2
Kernel Config: linux-at91-3.14.7.config