I'm having similar issue. I'm on 3.19.0-15-generic kernel but boot with systemd fails. I tried 4.0 mainline kernel (linux- image-4.0.0-040000-generic_4.0.0-040000), with which system booted but I cound not see lightdm prompt, only [ok] messages are shown. Though I can switch to other terminal (ALT+CTRL+F2) and check logs on 4.0 kernel.
** Attachment added: "kern.log" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1443630/+attachment/4387214/+files/kern.log -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1443630 Title: kernel BUG at /build/buildd/linux-3.19.0/drivers/gpu/drm/drm_crtc.c:537! To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1443630/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs