View Full Version : [all variants] Restrict LiveCD resolution

July 24th, 2008, 08:58 PM

How can I make my XUbuntu (or Ubuntu) live CD to start by default in 1024x768 mode.

The reason is I'll be using live CDs to run as a kiosks and I need them all to start in 1024x768 no matter what.


July 24th, 2008, 09:13 PM
Here (http://en.wikipedia.org/wiki/VESA_BIOS_Extensions#Linux_video_mode_numbers) is a table of video modes I think you want 773
So if you press F4 from the livecd boot menu you would enter vga=773
Hope that helps.

July 24th, 2008, 09:33 PM

That's only during a boot. Then X is taking over and uses something called DDC to query monitor for supported modes. In my case it defaults to 12801024 even if I ask it otherwise in my xorg.conf.

I modified /usr/bin/dexconf script on the Live CD to put my configuration in the xorg.conf that LiveCD's X will use.

When I start LiveCD my xorg.conf like in attached file.

But it's still starting in 12801024 instead of desired 1024x768.

I could add: Option "NoDDC" in Screen section but then I run into issues with vertical refresh. LiveCD boots to 1024x768 but the screen is shifted left 1/3 of the way.

I would appreciate any help.

July 25th, 2008, 04:53 AM
I guess you probably know about this:

Note: As of Ubuntu 8.04 and Xorg 7.3, the setup and configuration of /etc/X11/xorg.conf has changed. Please see the Xorg in Ubuntu 8.04 (https://help.ubuntu.com/community/XORGHardy) for more information.

For additional troubleshooting resources, please also see the Ubuntu X Team wiki (https://wiki.ubuntu.com/X)
Which is from the Community Docs on video configuration here (https://help.ubuntu.com/community/Video).

Just including that in case you aren't aware of all the changes.