You can use the Linux source tree to build standalone/external images for your Digi Embedded Yocto platform.
Prepare the sources and build environment
To follow a standalone/external build workflow, you need to:
-
Clone the Linux kernel repository (https://github.com/digi-embedded/linux.git) to your development machine if you haven’t already done so. Specify the appropriate branch to check out. For ConnectCore 6UL on Digi Embedded Yocto 3.0, the branch is: v5.4/dey-3.0/maint.:
git clone https://github.com/digi-embedded/linux.git -b v5.4/dey-3.0/maint
You can also create new branches for your own development needs, but you must periodically merge them with the official branches to get source code updates. -
Set up the build environment so your current shell session has the variables needed for the build, such as toolchain path, cross-compile prefixes, and target architecture.
-
If you don’t already have it, download the Digi Embedded Yocto toolchain for your platform from the Digi supportĀ page and install it. See Download and install the toolchain.
-
Source the environment setup script:
source /path/to/toolchain/environment-setup-cortexa7t2hf-neon-dey-linux-gnueabi
-
Unset the LDFLAGS variable (or the kernel won’t compile):
unset LDFLAGS
-
Configure the kernel
Now that the environment is ready, you can configure the kernel for your platform:
make ccimx6ul_defconfig
You can also look at the kernel recipes included in Digi Embedded Yocto: each recipe (.bb file) specifies a Linux branch (SRCBRANCH variable) and a set of machines that can use it (COMPATIBLE_MACHINE variable).
After running this command, you can modify your chosen configuration via an ncurses interface with:
make menuconfig
Change the kernel configuration as needed, then save and close the configuration tool.
If you wish to save your custom configuration for future builds, save it as a defconfig, copy the generated file to arch/arm/configs, and name it as you like:
make savedefconfig
cp defconfig arch/arm/configs/my_custom_defconfig
Compile the kernel
Once you have configured the kernel, you can compile it. To build a kernel image and the device tree blobs, run:
make -j8
The -j8 flag specifies the number of parallel jobs to run during the build. Set it to twice the number of cores on your development machine to speed up compilation. |
You can find the final kernel zImage in arch/arm/boot and the device tree blobs in arch/arm/boot/dts.
You can choose to compile only theĀ device tree blobs with:
make dtbs
For information on additional make commands, run:
make help