Does GDM and GNOME have different resolution settings?

kushalkoolwal · 05-02-2008, 04:49 PM

Hi,

Recently I noticed a strange thing on my Debian 4.0 system (2.6.24 kernel) running GNOME/GDM on my Intel 855 GME graphics card (i80 driver). My "Screen" section of xorg.conf file originally looked like this:

Code:

Section "Screen"
        Identifier      "Default Screen"
        Device          "Generic Video Card"
        Monitor         "Generic Monitor"
        SubSection "Display"
                Depth           8
                Modes           "1280x768" "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth           16
                Modes           "1280x768" "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1280x768" "1024x768" "800x600" "640x480"
        EndSubSection

With this setting as soon as my GDM login screen use to load, my monitor went blank (Out of range) although I knew that GDM was being loaded properly (through PC speaker). So I just entered my login/password blindly and I was able to login into my GNOME and I could see everything back on my monitor.

SO I removed the resoltuion "1280x768" from my xorg.conf file and now it looked like this:

Code:

Section "Screen"
        Identifier      "Default Screen"
        Device          "Generic Video Card"
        Monitor         "Generic Monitor"
        SubSection "Display"
                Depth           8
                Modes           "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth           16
                Modes           "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1024x768" "800x600" "640x480"
        EndSubSection

With this setting my monitor now did not go blank on GDM login screen. I was surprise to see this behaviour. I was under the impression that GDM and GNOME does share the same resolution i.e. if one works on a particular resolution, the other would also work.

Can somebody tell me what's going on? Is there any separate conf file for GDM in which we need to specify resolutions for GDM?

Thanks

makuyl · 05-02-2008, 05:11 PM

The [gkx]dm login screen takes the leftmost modeline resolution from xorg.conf. If you want a specific resolution for gdm, put it in the beginning of the line, so you might have for instance:
"1024x768" "1280x768" "800x600" "640x480"
That makes gdm use 1024x768 but would let you choose 1280x768 with a suitable sync rate for the desktop.

kushalkoolwal · 05-02-2008, 05:15 PM

Quote:

Originally Posted by makuyl

The [gkx]dm login screen takes the leftmost modeline resolution from xorg.conf. If you want a specific resolution for gdm, put it in the beginning of the line, so you might have for instance:
"1024x768" "1280x768" "800x600" "640x480"
That makes gdm use 1024x768 but would let you choose 1280x768 with a suitable sync rate for the desktop.

Thanks for your reply, but unfortunately it just won't work with 1280x768 even at 60MHz refresh rate. This again brings me back to my original question: Does GNOME and GDM treats resolution differently?

makuyl · 05-02-2008, 05:21 PM

Have you a different resolution under gnome? Check with "xrandr" from a terminal while in gnome.
Also you can lower the default depth by changing this:

Code:

Section "Screen"
        Identifier      "Default Screen"
        Device          "Generic Video Card"
        Monitor         "Generic Monitor"
        SubSection "Display"

To this:

Code:

Section "Screen"
        Identifier      "Default Screen"
        Device          "Generic Video Card"
        Monitor         "Generic Monitor"
        DefaultDepth    16
        SubSection "Display"

Here's something interesting about gdm resolution: https://help.ubuntu.com/community/Fi...7f4fbc891328c9