missing xorgcfg

[Phil Meyer]

Tim wrote:
> Frode Petersen:
>   
>>>> Btw, have anyone else got a xorg.conf with no entries in sections 
>>>> 'files' and 'modules'? 
>>>>         
>
> Tim:
>   
>>> I don't even have those sections.  Defaults are presumed without them.
>>>       
>
> Frode Petersen:
>   
>> This makes me a bit confused. Are all the entries that used to go here 
>> assumed to be default settings, or are they dropped for different 
>> technologies?
>>     
>
> It seems that more defaults are presumed, and a fair bit of
> auto-configuring each boot.  That latter's caused me problems, when I've
> turned on a system with the monitor un-powered.  When turned on, I had a
> generic 800x600 display, instead of the prior 1280x1084.  And I kept on
> getting the same issue with a monitor that it didn't have in its
> database, until I preset it with more details.
>
> After playing around over the last few days, this appears to be a
> minimal configuration set up by Fedora:
>
> # Xorg configuration created by system-config-display
>
> Section "ServerLayout"
>         Identifier     "single head configuration"
>         Screen      0  "Screen0" 0 0
>         InputDevice    "Keyboard0" "CoreKeyboard"
> EndSection
>
> Section "InputDevice"
>         Identifier  "Keyboard0"
>         Driver      "kbd"
>         Option      "XkbModel" "pc105"
>         Option      "XkbLayout" "us"
> EndSection
>
> Section "Device"
>         Identifier  "Videocard0"
>         Driver      "nv"
> EndSection
>
> Section "Screen"
>         Identifier "Screen0"
>         Device     "Videocard0"
>         DefaultDepth     24
>         SubSection "Display"
>                 Viewport   0 0
>                 Depth     24
>         EndSubSection
> EndSection
>
> About the only specific thing in it was the "nv" driver.  It beats me
> why a keyboard ought to be part of the X configuration, though I do see
> reason behind configuring a mouse in there.  It's struck me for quite
> some time that the mouse port ought to be part of the graphic card, more
> than anything else.  Let *it* work out where the pointer is, in
> hardware.
>
>   
Most xorg and commercial drivers try to determine the best values to 
set  by querying the monitor itself when the driver starts.

This method ignores any setting you have specified for resolution.

So you don't need a detailed xorg.conf any more for most monitors, but 
on the other hand, the default behavior of querying the monitor is not 
optimal in every instance.

The protocol and dataset are called 'EDID'.  If your monitor responds to 
an EDID request then most current drivers will do what the EDID data 
suggests.

Look in your /var/log/Xorg.0.log for the string 'EDID'.
A few lines below that you will see something like:

Virtual size is NNNNxNNNN

NNNNxNNNN is the resolution that the monitor recommended.  That is what 
will be used unless you turn that feature off.

When such a driver is started in 'headless' mode, it will always assume 
VGA (800x600) because that is the minimum allowed resolution for 
standard VGA (all PC type monitors are supposed to be VGA compatible).

If you specify:

HorizSync 15.0 - 150.0
VertRefresh 48.0 - 190.0
ModeLine "1920x1080i" 82.620 1920 2089 2153 2448 1080 1100 1105 1125 
+Hsync +Vsync interlace

in your xorg.conf, the EDID will not be used.

Figuring out what those values need to be is a topic in itself.