Karin Chan

Ubuntu: LightDM Black Screen When Using SSD Workaround

<div style="text-align: justify;"><b>Some Ubuntu <a href="http://askubuntu.com/questions/227385/xubuntu-lightdm-shows-blank-screen-half-the-time">users</a> <a href="https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1066410">are</a> reporting LightDM errors when using a <a href="http://www.amazon.com/gp/product/B007R67FNA/ref=as_li_tf_tl?ie=UTF8&tag=weup07-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=B007R67FNA">SSD</a>: about half the time when starting the computer, LightDM</b> (the default Ubuntu display manager) <b>doesn't load correctly</b> and only a black screen and a blinking command line cursor shows up. The issue isn't limited to those who are using a SSD, but it's a lot more frequent when booting Ubuntu from a solid-state drive.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">I too am experiencing this issue with Ubuntu 12.10 (not tested on older Ubuntu versions because I didn't have a SSD when I was using 12.04) and I've found <b>two possible workarounds which have worked for me so I thought I'd share them with you, in case you're experiencing the same issue</b>.</div><br /><a name='more'></a><br /><div style="text-align: justify;">It seems that the black screen with only a blinking cursor (though sometimes I've also seen the "System is running in low-graphics mode" error) issue occurs due to a race condition with LightDM and without any tweaks, the only way to load the desktop was to either switch to a tty (CTRL + ALT + F1), login and then restart Lightdm using the "sudo service lightdm restart" command or restart the computer. So here are two possible workarounds:</div><br /><br /><br /><b>1. Start LightDM with a delay</b><br /><br /><div style="text-align: center;"><a href="http://img.netupd8.com/lightdm-ubuntu12.10.png"><img alt="LightDM" src="http://img.netupd8.com/lightdm-ubuntu12.10_thumb.png" /></a></div><br /><div style="text-align: justify;">One way around this is to start LightDM with a delay. My system, with Ubuntu 12.10 64bit installed on a SSD boots in ~14 seconds so adding a 2 second delay isn't much, however, for some, a larger delay might be needed (it depends on the system / SSD). This isn't ideal but it's definitely better than having to manually start LightDM or restart the computer. </div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">I must also mention that from what I've read, this workaround doesn't always work, meaning that if before using it, LightDM wouldn't start 50% of the time, using this workaround doesn't necessary mean it will work 100% of the time. Since I've applied this tweak, LightDM has worked every time for me so this probably depends on the hardware / SSD and how fast the system boots.</div><br /><div style="text-align: justify;"><b>To start LightDM with a delay, edit the <i>/etc/init/lightdm.conf</i> file as root with a text editor (I'll be using Gedit below):</b></div><pre class="linux-code"><code>gksu gedit /etc/init/lightdm.conf</code></pre><br /><div style="text-align: justify;">And near the end of the file (line 47 for me under Ubuntu 12.10 with LightDM 1.4.0-0ubuntu2), <b>above "exec lightdm", add the following line and then save the file:</b></div><pre class="source-code"><code>    sleep 2</code></pre><br /><div style="text-align: justify;">"2" is the number of seconds used to delay starting LightDM. Like I was saying above, "2" was enough for me, but depending on your system, you might need to add a higher value.</div><br />This is how the end of the <i>/etc/init/lightdm.conf</i> file should look like after editing it:<br /><br /><div style="text-align: center;"><a href="http://img.netupd8.com/lightdm.conf.png"><img alt="lightdm.conf delay" src="http://img.netupd8.com/lightdm.conf_thumb.png" /></a></div><br /><br /><br /><b>2. Use GDM instead of LightDM</b><br /><br /><div style="text-align: center;"><a href="http://img.netupd8.com/gdm-ubuntu12.10.png"><img alt="GDM" src="http://img.netupd8.com/gdm-ubuntu12.10_thumb.png" /></a></div><br /><div style="text-align: justify;">The issue did not occur for me while using GDM and booting Ubuntu from a SSD, so if you don't want to add a delay to LightDM, you can install and use GDM instead.</div><br /><b>To install GDM in Ubuntu, use the following command:</b><br /><pre class="linux-code"><code>sudo apt-get install gdm</code></pre><br />Or install it via Synaptic, Software Center, etc.<br /><br /><div style="text-align: justify;"><b>When installing GDM, you'll be prompted to select the display manager: here, select GDM instead of LightDM.</b></div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">If GDM was already installed but you were using LightDM, you can switch to GDM by using the following command:</div><pre class="linux-code"><code>sudo dpkg-reconfigure gdm</code></pre><br />And then select GDM when prompted.<br /><br />More about switching between LightDM, GDM, etc. in Ubuntu, <a href="http://www.webupd8.org/2011/07/how-to-switch-between-gdm-lightdm-or.html" title="How To Switch Between GDM, LightDM Or KDM In Ubuntu">HERE</a>.

Ubuntu: LightDM Black Screen When Using SSD Workaround

Some Ubuntu users are reporting LightDM errors when using a SSD : about half the time when starting the computer, LightDM (the default Ub...

<div style="text-align: justify;"><b><a href="https://github.com/Nano77/gdm3setup">GDM3Setup</a>, a tool to tweak the GDM3 login screen / lock screen, has been updated recently to support the latest stable GDM 3.6.</b></div><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://4.bp.blogspot.com/-hhOAwWSRAKk/UJfg495YfwI/AAAAAAAALlQ/zbbuM52Zt_Q/s1600/gdm3setup.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="221" src="http://4.bp.blogspot.com/-hhOAwWSRAKk/UJfg495YfwI/AAAAAAAALlQ/zbbuM52Zt_Q/s320/gdm3setup.png" width="320" /></a></div><br /><a name='more'></a><br /><b>GDM3Setup features:</b><br /><ul><li>Change the GDM3 GNOME Shell / GTK theme</li><li>Change icon theme, wallpaper, cursor theme</li><li>Enable/disable automatic login</li><li>GNOME Shell: change logo, show date in clock, show seconds in clock</li><li>GTK: change font, disable user list, disable restart buttons</li></ul><br /><div style="text-align: justify;"><b>In my test, some GNOME Shell themes didn't work properly with GDM and caused it not to start,</b> so I suggest you don't change the GDM GNOME Shell theme! Also, an user has reported that the <b>automatic login feature causes issues too</b>. Only use these features if you know how to restore everything to default without a working login screen.<br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://1.bp.blogspot.com/-7k2I5TY3yuI/UJgzr2iar7I/AAAAAAAALmY/sJV0OHBWanI/s1600/gdm3.6-login-screen-background.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="gdm3 3.6 login screen" border="0" height="180" src="http://1.bp.blogspot.com/-7k2I5TY3yuI/UJgzr2iar7I/AAAAAAAALmY/sJV0OHBWanI/s320/gdm3.6-login-screen-background.png" title="gdm3 3.6 login screen" width="320" /></a></div></div><br /><br /><br /><h2>Download GDM3Setup</h2><br /><div style="text-align: justify;">GDM3Setup is available for Ubuntu, Debian, openSUS, Fedora and Arch Linux and can be downloaded from GitHub:</div><br /><div style="text-align: center;"><a href="https://github.com/Nano77/gdm3setup">Download GDM3Setup</a></div><br /><div style="text-align: justify;">Note: even though the GDM3Setup page says the Ubuntu deb package is for Ubuntu Oneiric Ocelot, it works with Ubuntu 12.10 Quantal Quetzal and the latest GDM 3.6.</div><br /><br /><br /><h2>How to change the GDM 3.6 background image</h2><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://2.bp.blogspot.com/-VKHy6Ub-DKA/UJgzzx7HXeI/AAAAAAAALmg/96u6CKnMiPM/s1600/gdm-3.6-lock-screen.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="gdm3 3.6 lock screen" border="0" height="174" src="http://2.bp.blogspot.com/-VKHy6Ub-DKA/UJgzzx7HXeI/AAAAAAAALmg/96u6CKnMiPM/s320/gdm-3.6-lock-screen.png" title="gdm3 3.6 lock screen" width="320" /></a></div><br /><div style="text-align: justify;">GDM3Setup supports changing the GDM 3.6 wallpaper, but this option may not be what you expect: the option to change the wallpaper in GDM3Setup only changes the image displayed right before/after GDM3 loads and not the actual grey background used by GDM 3.6 for the login / lock screen.</div><br />Until GDM3Setup gets an option for this, you can manually change the GDM 3.6 grey background image. The image used by default is located under <b><i>/usr/share/gnome-shell/theme/</i></b> and is called <b>noise-texture.png</b>.<br /><br /><div style="text-align: justify;">Like its name says, the grey image used by GDM 3.6 is a pattern, but you don't have to use a pattern and a regular wallpaper image works too. To change it, open Nautilus as root:</div><pre class="linux-code"><code>gksu "nautilus --no-desktop /usr/share/gnome-shell/theme/"</code></pre><div style="text-align: justify;">then make a backup of the original "noise-texture.png" image and replace it with the image you want to use as a background for the GDM 3.6 login / lock screen.</div>

How To Customize GDM 3.6+ Login / Lock Screen (Change Theme, Wallpaper)

GDM3Setup , a tool to tweak the GDM3 login screen / lock screen, has been updated recently to support the latest stable GDM 3.6. GDM3Setup f...

+ Read more »