Jamie's Random Musings
Various thoughts and adventures, including but not limited to Linux, Windows XP and Widows Vista, and assorted bits of hardware new and old.
Monday 13 October 2008, 3:14 PM
Linux and Laptop Screen Resolutions
First, the new release of Mandriva (2009.0), gets the screen resolutions exactly the way I want them, by default. What this means is that the laptop screen is 1280x800, always, and when the external screen is connected it is 1280x1024 and the two screens are set to "mirror", meaning they display the same content as far as possible, and the additional resolution of the external display is simply clipped off the bottom of the laptop display.
However, the Beta release of Ubuntu 8.10 (Intrepid Ibex) has added an interesting new twist. When the two displays are set to "mirror", as they are by default, it doesn't get the resolution right - it sets them both for 1024x768, which I think is the highest resolution they have in common - and which looks awful on both of them. But if I un-check "mirrored", it sets each of them up separately, I can choose the optimum resolution of each one, and I can position them adjacent to each other any way that I like. The desktop then becomes the sum of the two individual displays, and I move between them my simply moving the mouse around. Users of multiple displays will be familiar with this situation; I haven't used it in many years, but it turns out to be even nicer than I remember.
I then tried to un-mirror the displays in Mandriva, but it doesn't quite get it right. One or the other always falls back to 640x480 resolution and then tiles that to fill the display, and that is certainly not a useable situation. Too bad.
The result of all this is that Mandriva can do what I originally wanted and Ubuntu can't, but now Ubuntu is able to do something else which I like even more! What a pleasing development.
jw 13/10/2008
PreviousComments on this post
"I then tried to un-mirror the displays in Mandriva, but it doesn't quite get it right. One or the other always falls back to 640x480 resolution and then tiles that to fill the display, and that is certainly not a useable situation. Too bad."
Probably the framebuffer issue (I'm curious whether Ubuntu's using a large framebuffer by default, which makes this work out of the box, but needlessly wastes a ton of system memory if you're not actually using a multi-monitor setup).
If you work off the instructions here as a base:
http://wiki.mandriva.com/en/2008.1_Eee_External_Monitor
(Yes, it's for the Eee, but it really applies generically to any Intel multi-monitor situation), can you get it going?
The Intel driver guys keep promising me that automatic dynamic framebuffer re-allocation will be showing up Real Soon Now, but Real Soon Now doesn't appear to have come yet. :)
Hi Adam, and thanks for reading and commenting, as always.
Your comments are as usual exactly right. I followed the instructions in the article you referenced, and I now have the same side-by-side display setup on Mandriva. FYI, since I use Gnome rather than KDE, after changing the settings and restarting the X server, I go to System / Preferences / Screen Resolution (which actually runs gnome-display-properties), and I can turn mirroring on/off and change the relative screen positions there. It all works just great.
What Ubuntu does is sort of semi-automatic. When you go into Screen Resolution and un-check mirroring, it tells you that it has to reset the buffer size to accommodate your setup, so after you finish you have to log out/in or reboot to load the new values. Internally what it does is add a "Virtual" line to the "Display" properties, exactly as your instructions described doing manually.
Thanks again for the help. I will say again, Mandriva 2009 is a very impressive release.
jw 14/10/2008
