GSoC ’23: Documenting the OpenWrt compilation process to set up a PPA

GSoC ’23: Documenting the OpenWrt compilation process to set up a PPA

Getting the OpenWrt PPA set up will require understanding and documenting the current approaches for portable compilation of OpenWrt packages. This is my first impression of this task.

When I verified the “hello world” program provided and verified by Zoobab correctly compiled, I have looked to see how exactly this process works. The Docker build script depends on the toolchain compilation script. They both require an internet connection, and I will have to keep this in mind when porting this to make an OpenBuildService (OBS) package: “Mentioning repositories directly is not allowed (using obsrepositories:/ is ok)“.

Interesting technical details I found while researching how to transfer the current Docker approach to OBS:
– At first I did not know what the flag V was in `make V=s`. It turns out it turns on verbose compilation output on console on the OpenWrt build system. (I was surprised when I saw this was undocumented in the new version of the guide.)
– The package manager for OpenWrt uses ipk files. The helloworld package (that has been compiled under the OpenWrt SDK) has been successfully installed inside an openwrt rootfs and runs great!
– The current system uses cascading Docker images (multi-stage builds). This is done by producing the OpenWrt SDK container image first and then a new Docker image compiles the actual system. This is useful because it means the actual package being compiled is kept separate from the source itself.
– It turns out that obs-build from OpenBuildService assumes a working chroot so one must be created manually. The actual container must be merged in separately into the upstream project, outside of obs-build.

A message from our working hello world package:

root@localhost:/# helloworld
Hello world!
MyClass::MyClass()
MyClass::printMessage()
This is my message to print

I can’t wait to learn more and get up to speed on how to approach this project. I’ll see you later!