I am probably making some kind of stupid mistake but cannot figure out the problem. Therefore, I would really appreciate if someone could give me a hint on how to proceed. I upgraded the PC that I use to run the ACRN hypervisor from 8 GB of RAM to 40 GB of RAM by adding two 16 GB bars (previously I had two 4 GB bars). When I use the generic Ubuntu kernel, everything works without problems and the memory is recognized and usable. However, when I use the ACRN kernel (version 2.6), and run the "free" command, only 16 GB of the memory are shown. When running "sudo lshw | grep -A 9 bank", all four bars are shown correctly as you can see below.
So far I only created a new board configuration file and recompiled kernel and hypervisor. Apart from that, I did not make any change to the system and installation except for adding the two RAM bars.