Hal_core is a lightweight hal environment. The installed size is approx 6.8Mib

A hal environment can be used as platform to run realtime applications like:

motion controllers 
robots
cnc-machines 
parport, ethercat applications
research and development 
scientific projects

Packages needed for the installation (at the bottom):

https://github.com/grotius-cnc/hal_core/tree/main/src#readme

To install:

Install hal-core:
$ git clone https://github.com/grotius-cnc/hal_core.git /opt/hal-core
$ /opt/hal-core/./make

To run:

$ /opt/hal-core/./runtest

https://user-images.githubusercontent.com/44880102/129791198-ab705999-23ca-4004-a5f5-f0bd3357b47e.mp4