Xorg - how to disable some video modes?

[Alejandro Pulver]

On Tue, 10 Jan 2006 12:56:01 +0100
User Gandalf <gandalf at messias.qhigh.com> wrote:

> Here is the config. I made a mistake. You were right. I forgot to use 
> DefaultDepth. But I do not understand why I need it, since 24 is the 
> only depth specified in my screen section,
> 

Maybe it was trying to use another depth (like 16), and because it
wasn't present in a "Display" subsection it used all the available
modes by default.

> Without "DefaultDepth 24" it starts with 1900x1440. With
> "DefaultDepth 24" is starts in 1024x768 but it does not allow me to
> switch to 1280x1024 with Ctrl-Alt-Plus.
> 
> Thanks,
> 
>    Les
> 

You can only use the modes that are listed in "Modes", that's why you
can't switch to 1280x1024. You have to add "1280x1024" to the "Modes"
line (when not using DefaultDepth 24 it seems all modes are listed
there).

Then X will start in the higher resolution it can find in "Modes", to
solve this you can put in .xinitrc the following command (which will
change the resolution after X starts):

xrandr -s 1024x768

You can also see the list of available resolutions with that command
(without parameters).

If you have something like "exec /usr/X11R6/bin/xfce" in .xinitrc be
sure to put the "xrandr -s 1024x768" command before it (the "exec"
replaces the shell by xfce, so everything after the exec will never
be executed).

For example (xorg.conf section with 1280x1024 added to Modes):

Section "Screen"
       Identifier "Screen0"
       DefaultDepth 24
       Device     "Card0"
       Monitor    "Monitor0"
       SubSection "Display"
               Viewport   0 0
               Depth     24
               Modes   "1280x1024" "1024x768"
       EndSubSection
EndSection

Best Regards,
Ale