Dual displays

I was at the last Atlanta Python meeting this month, and noticed some presenters are still having issues getting dual displays to work. It is something I haven’t had to do in Linux. But I decided to try it out.

I found this video which explained how to do everything using nvidia-settings.

I didn’t follow the directions completely. First I ran sudo nvidia-settings, and enabled my second LCD. Once I made my changes, I saved the new xorg.conf file and rebooted (enabling dual screens requires X restart, I did the reboot to keep things safe). Everything worked.

I should note, I did back up my xorg.conf file, in case things went terribly wrong.

Then I began to wonder what the difference between Xinerama and RandR. This time I restored my xorg.conf file back to the original and rebooted. I found this blog post, which seemed to answer my questions best.

I found this tid-bit of information: RandR gets disabled in the core X server when Xinerama is enabled.

Well after trying different options, I decided to run my second monitor as it’s own desktop.  The two LCD’s are different sizes and resolutions.  When I combined the two (extended), things just didn’t line up properly and the back ground was stretched.  Later when I played a DVD the aspect ratio was off, due of the increased height (I am running the LCD’s one on top of the other).

A few tricks.  If everything goes badly, restore your xorg.conf file and delete your {home}/.nvidia-settings-rc file.  Then restart X (no need to reboot).

While RandR is suppose to be a nicer way to dynamically adjust X screens, it appears NVidia has still not fully supported RandR.  That suits me just fine for now, as nvidia-settings works well.  I will test plugging my laptop into a random VGA display (projector) next to see how it adapts.  With the setting on AUTO, it should recognize things just fine.  Yeah right…what am I thinking.


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