I've added gdm3 as affected. The fact that sddm launches a working Wayland gnome-shell is a good sign that this is a GDM bug.
** Also affects: gdm3 (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1711936 Title: Severe graphical corruption in gnome-shell with nouveau [Nvidia GeForce 8400M GS] To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gdm3/+bug/1711936/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs