unity-greeter ignores lightdm display resolution and DPI settings

[Tim Edwards]

I have a laptop with a very high-res screen (Lenovo Yoga 2 Pro with 3200x1600 screen). To make this more usable I set the display to a resolution of 1920x1080 and a higher DPI of 120x120 in the LightDM settings:
xserver-command=X -dpi 120
display-setup-script=xrandr --output eDP1 --mode 1920x1080 --primary

These settings are ignored or overridden by the unity-greeter. Other greeters, e.g. lightdm-kde-greeter, correctly apply these settings.

Steps to reproduce:
1. Change your DPI and resolution settings to be something other than the default for your laptop's display in /etc/lightdm/lightdm.conf, using xserver-command and display-setup-script as above
2. Ensure lightdm is set to use the unity-greeter
2. Restart lightdm or reboot the laptop

Expected results:
The lightdm Unity login screen is shown with the resolution and DPI you set using xserver-command and display-setup-script in lightdm.conf

Actual results:
The settings are ignored/overridden and lightdm shows the login screen using the default resolution and DPI for your device

Workaround:
Use lightdm-kde-greeter:
sudo apt-get install lightdm-kde-greeter
greeter-session=lightdm-kde-greeter

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: unity-greeter 14.04.10-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-36.63-generic 3.13.11.6
Uname: Linux 3.13.0-36-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.4
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Sep 29 12:08:56 2014
InstallationDate: Installed on 2014-09-16 (12 days ago)
InstallationMedia: Ubuntu-Server 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2)
SourcePackage: unity-greeter
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[gobble (gobbledegeek)]

I use a dell xps 13 9343 with a 3200x1800 screen res and adding the command xserver-command=X -dpi 144 to the lightdm.conf results in Ubuntu booting in low res troubleshooting mode - I never get to the unity-greeter screen. From the logs I gather that X shuts down. I had to boot into recovery mode and remove that line to be able to login.