1) I used virtualbox 6.0.0 on disco (my desktop machine) # I guess it doesn't really matter but I prefer giving more details than less ;)
2) Deploy a VM with Ubuntu 18.04.1 (which come w/ 4.15)
3) Make sure in the VM setting that the display uses 'VMSVGA' which will force the OS to pick 'vmwgfx' video kernel driver. (you can confirm with 'lspci -nnvv' command.
4) apt-get dist-upgrade
Then reboot and the login screen won't be shown again using v4.15 kernel.
Switch to 4.18 will work.
My reproducer:
1) I used virtualbox 6.0.0 on disco (my desktop machine) # I guess it doesn't really matter but I prefer giving more details than less ;)
2) Deploy a VM with Ubuntu 18.04.1 (which come w/ 4.15)
3) Make sure in the VM setting that the display uses 'VMSVGA' which will force the OS to pick 'vmwgfx' video kernel driver. (you can confirm with 'lspci -nnvv' command.
4) apt-get dist-upgrade
Then reboot and the login screen won't be shown again using v4.15 kernel.
Switch to 4.18 will work.
Regards,
Eric