What is behind the build process?¶
Build process summary:
- creates development environment on top of AMD64 Ubuntu 16.04 LTS,
- downloads proven sources, applies patches and uses tested configurations,
- cross-compiles universal boot loader (u-boot), kernel and other tools and drivers,
- packs kernel, uboot, dtb and root customizations into debs,
- debootstraps minimalistic Debian Wheezy, Jessie and Ubuntu Trusty into SD card image,
- installs additional packets, applies customizations and shrinks image to its actual size.
Check this image compiling example with partial cache.
Creating compile environment¶
At first run we are downloading all necessary dependencies.
Using board configuration¶
We need to get some predefined variables about selected board. Which kernel & uboot source to use, modules to load, which is the build number, do we need to have a single partition or dual with boot on fat, which extra drivers to compile out of the kernel tree, …
When we know where are the sources and where they need to be the download / update process starts. This might take from several minutes to several hours.
In patching process we are appling patches to sources. The process is defined in:
lib/patch/kernel/sun7i-default lib/patch/kernel/sunxi-dev ... lib/patch/u-boot/u-boot-default lib/patch/u-boot/u-boot-neo-default ...
Patch rules for subdirectories are: KERNEL_FAMILY-BRANCH for kernel and U-BOOT-SOURCE-BRANCH for U-boot.
Debootstrap creates fresh Debian / Ubuntu root filesystem templates or use cached under:
To recreate those files you need to remove them manually.
When root filesystem is ready we need to install kernel image with modules, board definitions, firmwares. Along with this we set the CPU frequency min/max, hostname, modules, network interfaces templates. Here is also the place to install headers and fix + native compile them on the way.
Each distributin has it’s own way of doing things:
- serial console
- different packets
- configuration locations
Each board has their own tricks: different device names, firmware loaders, configuration (de)compilers, hardware configurators
You can build a desktop withing the image. Consider this feature as experimental. Hardware acceleration on Allwinner boards is working within kernel 3.4.x only.
This place is reserved for custom applications. There is one example of application - USB redirector.
There is an option to add some extra commands just before closing an image which is also automaticaly shrink to it’s actual size with some small reserve.
It will be something like this:
compile.sh compile execution script lib/bin/ blobs, firmwares, static compiled, bootsplash lib/config/ kernel, board, u-boot, hostapd, package list lib/documentation/ user and developers manual lib/patch/ collection of kernel and u-boot patches lib/scripts/ firstrun, arm hardware info, firmware loaders lib/LICENSE licence description lib/README.md quick manual lib/common.sh creates environment, compiles, shrink image lib/configuration.sh boards presets - kernel source, config, modules, ... lib/distributions.sh system specific installation and fixes lib/main.sh user input and script calls lib/makeboarddeb.sh creates board support package .deb lib/repo-update.sh creates and updates your local repository lib/repo-show-sh show packets in your local repository lib/upgrade.sh script to upgrade older images sources/ source code for kernel, uboot and other utilities output/repository repository output/cache cache for root filesystem and headers compilation output/debs deb packeges output/images zip packed RAW image userpatches/kernel put your kernel patches here userpatches/u-boot put your u-boot patches here userpatches/ put your kernel config here