A Linux PC in required to cross compile the Kernel image.
This procedure has been tested on:
Follow this article to install the Toolchain requested to compile the sources:
Moving from the Kernel 4.19 to 5.4 it is requested to compile the at91bootstrap bootloader following this guide:
The previous version of at91bootstrap 3.9.1 will not work correctly
Open a terminal on your Linux PC and download the Linux Kernel sources from the main stream repository:
extract the Kernel sources from the compressed file by typing:
tar xvfJ linux-5.4.163.tar.xz
move inside the folder created:
copy the basic kernel defconfig file suggested from us
wget https://www.acmesystems.it/www/acqua_compile_kernel_5_4/acme-acqua_defconfig -O arch/arm/configs/acme-acqua_defconfig
Set the defconfig:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- acme-acqua_defconfig
If you need to customize the Kernel configuration or you just want to take a look around the Kernel setup type:
make ARCH=arm menuconfig
and navigate inside the Kernel configuration using the arrow keys and following the help provided by the menuconfig interface.
If you are using a TFT with your Acme board change the file
using these commands:
rm drivers/gpu/drm/panel/panel-simple.c wget https://www.acmesystems.it/www/acqua_compile_kernel_5_4/panel-simple.c -O drivers/gpu/drm/panel/panel-simple.c
Download the Acqua device tree file:
wget https://www.acmesystems.it/www/acqua_compile_kernel_5_4/at91-sama5d3_acqua.dts -O arch/arm/boot/dts/at91-sama5d3_acqua.dts
Now compile the device tree file:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- at91-sama5d3_acqua.dtb
Compile the Linux Kernel sources and generate the binary compressed image file to save in the first partition of microSD card.
make -j8 ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- zImage ... Image arch/arm/boot/zImage is ready
The image generated contains the Linux Kernel and all the built-in device drivers (option [*] in menuconfig) compiled with it.
Al the drivers compiled as external modules (option [M] in menuconfig)
need to be compiled and saved in the rootfs
/lib directory on the second
partition of the microSD. We didn't use any [M] flag in our defconfig so this procedure
is not requested but. in case you add something. these are the commands to use
to compile them:
make modules -j8 ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make modules_install INSTALL_MOD_PATH=./modules ARCH=arm
Write the Linux Kernel image and the device tree blob in the first microSD partition:
sudo cp arch/arm/boot/zImage /media/$USER/boot sudo cp arch/arm/boot/dts/at91-sama5d3_acqua.dtb /media/$USER/boot/at91-sama5d3_acqua.dtb
Write the Linux Kernel modules inside the second microSD partition:
sudo rsync -avc modules/lib/. /media/$USER/rootfs/lib/.
At the first access to the board command line update the module dependencies by typing this command:
make ARCH=arm savedefconfig
defconfig contains your configuration. You could rename and copy it in
cp defconfig arch/arm/configs/my_defconfig