Installed the image Armbian_20.08.1_Rockpi-4b_buster_current_5.8.6.img.xz . Then, in armbian-config -> Software, I had installed linux headers + source.
I got two new directories:
If I execute:
uname - r
root@pi:~# uname -r
The kernel version and installed source/headers are not the same, so they are useless. How to get the correct source/headers?
When first boot, the OS asked for locale/timezone settings, I did hit ENTER as default and it set the locale language to Slovene. When doing apt-get update, there was an error saying about missing files on the server.
Since I am not very familiar with this language I changed to en.US-UTF-8. Then I redo apt-get update, it updated without problems.
I had removed headers and source via armbian-config. Done update & upgrade, this time no problems. The version is now 5.6.12-rockhip64
Reinstalled back headers, correctly. Installed source, this time I had to choose which one, so I choose 5.6.12-rockhip64
It seems solved, now. The local language could be an issue.