We've stored our code in Gerrit, and like the Android developers before us, we use repo to manage the projects in our Gerrit repositories.
To get started, first, you're going to need to pull down a copy of the repo tool from our public facing sites and add it to your path:
mkdir -p bin export PATH=$PATH:$HOME/bin curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo chmod a+x ~/bin/repo
Make sure you've initialized git with your name and email address, and have configured it properly for fetching the sources:
git config --global user.name "Your Name" git config --global user.email "you@example.com"
Once you‘ve done this, you’re actually ready to check out the sources. Make a new directory where you'd like it to live, and do the following:
repo init -u sso://spacepark/manifest -m debian.xml repo sync -j$(nproc)
After a short wait, you'll be ready to go for making changes to the repository and building images.
To build the tree, first you need to prepare your environment:
source build/setup.sh
At this point you‘ll have a couple of extra functions available to navigate around the tree and build things in part or in whole. For now, let’s just build the whole shebang. First you need to make a debootstrap tarball, and then finally build the tree:
mm debootstrap make-bootstrap-tarball m -j$(nproc)
In about an hour, if the tip of the tree is good, you should have images ready to flash available in the out/ directory. To get to the tree quickly, use the j command to “jump” into the product directory, and then use the flash.sh script to flash everything to an attached board (note: the board will need to be in fastboot mode, and everything previously stored on the emmc will be erased).
j product flash.sh
To build the world for an sdcard, build the sdcard target:
m sdcard
The build system is relatively straightforward. It's a selection of split out multi-target makefiles defined in the build/ directory. Each makefile is designed to be as standalone as possible so that each can be built individually using the mm command, or collectively using m.
Adding modules is also relatively straightforward, assuming a decent understanding of GNU Make rules. An example of how to get started is available in the build/template.mk script. Simply copy this file to a new filename, and then add the following line to the list of includes in the toplevel build/Makefile file:
include $(ROOTDIR)/build/your-module.mk
Note that targets and clean are special partial targets. The rules must be defined with a double colon (::) and not added to your module's .PHONY target. Additionally, the output of the targets command is a list of strings of the form:
targetname - some short description of your target
This is actually parsed by the mm function to help with tab completion. It's relatively robust in the face of spaces, but you must separate your targetname with a dash (-) from the description, or the completion routine will likely break.
If you follow the conventions in the template, mm will autocomplete your module and it's targets listed in the targets make target.
The m function can be called from any directory in the filesystem to build the entire tree from the ground up. Effectively the command does a pushd to the root of the tree and issues a make command. You can specify any options or targets you'd like to build, including the targets command to have a look around in the build system.
The mm function can, like the m function, be called from any directory in the filesystem to build an individual module. It has autocompletion functions, so simply typing mm and then hitting TAB will autocomplete the list of modules available. Additionally, if you press TAB again, after you've autocompleted a module name, it will autocomplete the list of targets available in that module, as returned by the targets target.
This is a kind of switchboard of sorts that lets you jump around the tree quickly. Many of the paths are arcane because of historical reasons, so this tool was written to make things a bit easier.
If you issue the j command with no arguments, it will automatically change your current working directory to the root of the tree. If, however, you issue j help, it will list a list of target names you can “jump” to. You can open up build/setup.sh to see which ones are currently defined, or just jump around and explore.
Contains build scripts, the setup.sh script and rootfs overlay, as well as some additional tooling.
Contains the debootstrap tarball you must build before starting any other build lives here. This directory is ephemeral and doesn‘t exist on a first clone, but will also not be removed when the clean target is run. Bear in mind: if you update the package list in build/debootstrap.mk, you’ll need to re-reun mm deboostrap make-debootstrap-tarball to regenerate this.
Contains i.MX8M Enterprise-specific configuration files, kernel configurations, and other device-specific information. Cloned from the AndroidThings repository and will likely migrate as time goes on.
Contains this documentation, as well as other documentation about the build system and working in the tree.
Contains the kernel and u-boot bootloader source code. These are forks of the original AndroidThings source code.
Contains the atheros and qualcomm Wifi firmware blobs. Cloned from the AndroidThings repository and will likely migrate out as time goes on and bom selections change.
Contains the Vivante upstream binary drivers for the GPU. These are required to get the displays working. Also clonsed from the AndroidThings repository.
The ephemeral directory that contains both local host binaries and tools, as well as build artifacts and the final images produced. It has a specific structure documented elsewhere.
Debian package sources used to build the packages installed to make the distribution more functional for the Enterprise board.
Contains the prebuilt toolchains to build for an aarch64 target.
Contains AndroidThings tools like bpt, as well as fastboot and other low-level tooling for the host and device-side userlands. Currently the only parts we're using in the tree are fastboot and bpt. Cloned from the AndroidThings repository.
Contains many NXP specific binaries for various peripherals used in the final build to get peripherals working.