@Sachin: You mentioned another command in the issue you linked to. Thus, I
tried "sudo /etc/init.d/virtualbox start". But this only resulted in "No
suitable module for running kernel found".
@GNUser: Thank you very much for your elaborations. However, I think I didn't
manage yet to use the package from jxself.
I followed the instructions from here [1] but now I don't know the correct
procedure to get rid of my old linux-libre package and using the new one from
jxself.
[1]: http://jxself.org/linux-libre/