If you want a "clean" starting point to build under Ubuntu 20.04, refer to the WSL2 page that I wrote on the Wiki. It was written only last year, and it should contain the complete instructions for setting up a new 20.04 environment - just skip the WSL2-specific portion at the start.
Personally I use 20.04 for my development, under VMWare Player.
Thanks for your answer.
Mostly just got some problems with which enviroment for the right compiler.
Im trying to create a script which mostly automaticly do everything.
For example right now, if the container is downloaded and your exec into it, there are several scripts to execute.
Im not so famillar with your compilers right now, thats why i need some time. :x
Right now, it pulls both repos, create a backup with rsync. and linking the basic enviroments. and a simple stupid script for pulling or resetting the complete pulled repo.
Options which i want to include are with make commands; are like "make rt86u" is automaticly linking to the correct dir and creates the firmware and move it to the mounted directory, which is where you start the container.
If you get little bit familar with docker, its mostly a great solution. im writing a readme right now also. with the readme could everyone create a firmware, also who isnt familar with docker.
if i feel like its production ready, i will post it here.