Kubuntu 18.04 gives black screen when SDDM starts (no login)

Graphics / Linux Linux
12

I was thinking that maybe I had an automatic copy of my xorg.conf when upgraded (the one that worked well before), and it was there, so I did a test with that one and worked!. So I will write down here the change and configuration that made work again my Nvidia in a laptop with Optimus.

Added lines 9 and 10 to usr/share/sddm/scripts/Xsetup:

#!/bin/sh
# Xsetup - run as root before the login dialog appears

if [ -e /sbin/prime-offload ]; then
    echo running NVIDIA Prime setup /sbin/prime-offload
    /sbin/prime-offload
fi

xrandr --setprovideroutputsource modesetting NVIDIA-0
xrandr --auto

My working xorg.conf:

Section "ServerLayout"
    Identifier "layout"
    Screen 0 "nvidia"
    Inactive "intel"
EndSection

Section "Device"
    Identifier "intel"
    Driver "modesetting"
    BusID "PCI:0@0:2:0"
    Option "AccelMethod" "None"
EndSection

Section "Screen"
    Identifier "intel"
    Device "intel"
EndSection

Section "Device"
    Identifier "nvidia"
    Driver "nvidia"
    BusID "PCI:1@0:0:0"
    Option "ConstrainCursor" "off"
EndSection

Section "Screen"
    Identifier "nvidia"
    Device "nvidia"
    Option "AllowEmptyInitialConfiguration" "on"
    Option "IgnoreDisplayDevices" "CRT"
EndSection

Thank you very much generix, now I could properly work again in Blender and my CAD software.