Ubuntu – Laptop monitor stays black with an external display connected to the Asus UX32VD

asusmultiple-monitorsunity

Whether I run Ubuntu as a live-USB or install it, I always have two trash bins on the Unity Launcher. Both work, and both open the same location.
This seems a bit redundant; what could be done about it?

Update: Turning auto-hide on made it obvious that I have multiple Launchers showing. With auto-hide off, they simply overlap, making it look like there's a double trash icon, but with auto-hide enabled, I can display one Launcher (and therefore one trash icon) at a time. Still, two are running simultaneously.

Second update: This problem appears to be caused by the way Ubuntu handles multiple displays on my Asus UX32VD Ultrabook. Somehow, the laptop display cannot be used while my external display is connected. It is shown in the Displays list, but remains black no matter how I configure it.
The external display runs at 1920×1200, the laptop monitor should run at 1920×1080. It therefore becomes obvious that the Launcher that's supposed to run on the laptop display, is actually displayed on the external monitor.
Using nomodeset as a kernel parameter as indicated here makes the laptop display inaccessible altogether, detecting the external monitor as the laptop display and making resolutions other than 1920×1200 inaccessible. That is not an option.
Without nomodeset, the external monitor works as it should, but the laptop monitor stays black. When I disable the laptop monitor, the external display goes black, too.

Screenshot

Best Answer

First check that the Ubuntu ISO is correct by checking the md5sum or sha1sum.

To check, run the following command on the terminal:

    md5sum /path/to/ubuntu/image.iso

And make sure they match to the ones give on the release page.

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If they don't match, download the image again.
However, if they do match, this would be a bug. Please report it on launchpad.net.

Update: As answered here, it can be a gpu problem. If you've nvidia card, make sure all the drivers are installed.

Then, run the following command from the terminal:

sudo nvidia-settings

You can now configure multiple displays and gpu settings.

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Ubuntu – Laptop screen blank after login when external monitor is not connected

To issue X commands from vt1, you need to specify the display. E.g.:

DISPLAY=:0 xrandr --auto

The monitors.xml config file is what GNOME uses to set up your multihead layout, however it's unlikely to be the source of your trouble. Theoretically deleting it and rebooting would force GNOME to go back to its defaults, if it was a bug in the GNOME config tool.

/etc/X11/xorg.conf is what X uses to configure itself. With your Intel HD graphics system you shouldn't need an xorg.conf at all; if there is one present, you can try deleting it and rebooting. But I don't think that's the source of your trouble either.

I don't think your .dmrc is relevant. You could test going into a guest session and see if you can reproduce it there; if you can then it's not going to be any of your user config files.

Beyond that, there's a variety of things that can cause this, but without seeing some logs or more test results it's hard to guess what it could be.

With Intel video cards, only two of your outputs can be live at one time. Especially with these newer systems they have a lot more than two possible outputs (HDMI, DVI, VGA, LVDS, ...) and there are various ways the linux kernel can get confused and hook up to the wrong thing. Sometimes it's a bit of a race condition what outputs get enabled. Some of the outputs that the video card is capable of aren't even hooked up to a physical port on your computer.

If the system were in front of me, the things I'd start looking at would be xrandr to see what possible outputs were present and what ones X thinks are connected. Next I'd enable graphics debugging (sudo xdiagnose, first option), and then reboot and study dmesg from with and without the problem to see how the kernel was picking which outputs to turn on.

Hopefully that gets you on a productive path. Blank screen bugs can be caused by a lot of different things and it's hard to diagnose it merely based on symptoms, but the above steps should get you far enough into the problem that it'll become diagnosable.

Ubuntu – Huge elements on secondary monitor with lower resolution

As far as I know the only relatively easy way to get independent scaling between monitor and built-in display is to use the Wayland windows system (instead of the current Xorg).

This is available in Ubuntu 18.04, although Xorg window system is the default, you can switch at the login screen

Then in your 'Display Settings' you can set 200% for the built-in display and 100% for the monitor.

But there are still major issues. I have created a separate question with the issues I found when using Wayland. Currently only the terminal windows and file explorer windows handle the separate scaling properly. All other applications still use the scaling of the built-in display when on the monitor. This makes for a really ugly monitor as you have some windows scaled to 100% and others to 200%.

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Ubuntu – Laptop screen blank after login when external monitor is not connected

Ubuntu – Huge elements on secondary monitor with lower resolution

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