I followed this guide https://docs.ros.org/en/foxy/Tutorials/Building-Realtime-rt_preempt-kernel-for-ROS-2.html
At building time (make -j nprocdeb-pkg) I get an error, that I think I solved following the second answer of this guide (https://askubuntu.com/questions/1327749/error-in-compiling-installing-realtime-kernel-on-ubuntu-20-04-2-lts)
When I reboot the pc I get an error that I think I solved following the first answer of this guide disabling secure boot (https://askubuntu.com/questions/1081472/vmlinuz-4-18-12-041812-generic-has-invalid-signature)
Now when I turn on the pc, it can boot the linux kernel for preempt rt but after boot it stucks with the cursor that I can not move on a black screen.
How can I solve this problem?