A Linux PC in required to cross compile the Kernel image.
This procedure has been tested on:
Using an Intel PC is required to install these packages
It is advisable to have a Debug Port Interface like DPI or USB-3V-SER to check the error messages during the kernel bootstrap
Here we will illustrate how to compile the source available on the Microchip website site and repository:
Open a terminal on your Linux PC and download the Linux Kernel sources from the main stream repository:
wget https://github.com/linux4sam/linux-at91/archive/linux-5.4-at91.zip
Extract the Kernel sources from the compressed file by typing:
unzip linux-5.4-at91.zip
Move inside the new folder:
cd linux-at91-linux-5.4-at91
Create with git a new branch of Linux Kernel sources called acme to keep a trace of any changes from the Kernel mainline.
Install git on your PC:
sudo apt update
sudo apt install git
Create a local git repository and the new branch acme:
git init; git add .; git commit -m "linux-5.4-at91"; git branch acme; git checkout acme
Download the Acme Systems patch for this Kernel version. It add just the Acme boards defconfig, device trees and small fewbug fixes (don't change the version number in this case):
wget https://raw.githubusercontent.com/AcmeSystems/acmepatches/master/linux-4.19.x.patch
and apply it by typing:
patch -p1 < linux-4.19.x.patch
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.
make ARCH=arm savedefconfig
The file defconfig contains your configuration. You could rename and copy it in arch/arm/configs/
cp defconfig arch/arm/configs/my_defconfig
Now compile the device tree file requested by your board by selecting one of the following commands:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- acme-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
Insert a formatted microSD with the boot loader (at91bootstrap) and the rootfs contents already created in your Linux PC and copy on it these files:
Write the Linux Kernel image and the device tree blob in the first microSD partition:
sudo cp arch/arm/boot/zImage /media/$USER/boot
sudo cp arch/arm/boot/dts/acme-acqua.dtb /media/$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:
depmod -a
If you want to create a patch with the changes you have made on the vanilla Linux kernel use these commands:
git checkout acme
git diff master > acme.patch
To revert a patch applied type:
patch -p1 -R < ../acme.patch
Acme Systems srl provided this documentation "as is" without warranty or guarantees of any kind. We not provide any direct support for the Open Source software which can running on our board but, through these pages and forum posts, we provide all of the information required to obtain the sources, install, use and update the Open Source software available on Internet.
Please note that all of the software we talking about is Open Source so you have to check any license provided by the software authors before using it in any commercial or non-commercial product, by yourself.
Please contact us note that WE ARE MAINLY HARDWARE DESIGNERS and NOT LINUX GURUS and therefore could be better to post your questions to the Acme Systems forum and ensure that all of the site contributors and large software community can read and reply to your questions.
Una iniziativa no-profit di Acme Systems srl per supportare l'Arte: https://art.acmesystems.it