The goal of this project to to house the various repositories layers needed to build a Yocto image for Raspberry Pi.
The repository will use git submodules to reference the meta-* layers and include Bitbake configuration files to ensure
that all layers are added correctly to the project. In the future I hope to add some convince scripts that will be able
to configure the build area bases on user select criteria.
Yocto allows the building of an embedded Linux distro that is tailor made for a specific needs and platform while also being versatile to support other SoC/architectures if needed in the future (and given the prices and availability of pis, it is a very real possibility). While it is certainly possible to use a stripped down distro like Raspberry Pi OS Lite, the image is still 300MB+ and still has to be configured inorder to run you application software. With Yotco all the configuration is handled during the Bitbake process and the output is a configured and ready to deploy image with all the software you need and nothing more.
Currently I use Fedora for my personal laptop (which is not a supported build environment). Regardless if you use a supported
build environment natively, it is generally a good idea to use a container to ensure that all dependencies are meet. I use
the crops/poky container for my builds. Below is the command to launch a container
with work area mounted, just replace $REPO_ROOT with location of this cloned repository.
docker run --rm -it --net=host -v $REPO_ROOT:/workdir crops/poky --workdir=/workdir
To get started, simply source the init-build script in the Docker container with the desired target directory, like so:
source init-build raspberrypi0-wifi
Once that script is run, you bash shell should now have everything it needs to start Bitbaking.
To build an image simply run the bitbake command. Currently there are two images in the meta-application layer:
transit-board-dev-image: Image that contains application and debug tools like gdb, objdump, and allows paswordless ssh root access to the device.transit-board-prod-image: Image that contains application and necessary dependencies.
Openembedded provides support for the qemu emulator. It can be quite helpful when debugging build issues quickly without having
the need to deploy to an actual target device. Since I do my builds in a Docker container, I also have to run the emulator in the
container as well. To build for qemu, change the MACHINE variable to qemuarm64 in the local.conf file. Then Bitbake the desired
image. Once complete you can run emulator using the command below:
runqemu nographic slirp
We use nographic since we want a headless instance and slirp since we are running in a container and tun/tap interface is not needed
for networking.
Stefan Bossbaly