Hi,

Over the past few weeks I changed from Slackware 10 to 10.1 (upgraded rather than reinstalled). I've only just noticed something that has gone wrong... My screen resolution is - as I usually want - 1600x1200. The virtual desktop size is exactly the same - a standard desktop.

If I try to change my resolution (actually I want to change the virtual desktop setting - but keep it 1:1 with the screen resolution) to anything else (800x600 for example) then the screen resolution stays the same at 1600x1200, but the virtual desktop is shrunk to 800x600 and fills only 1/4 of my screen.

I'm embarrased - I haven't found the reason for this, so please help put me out of my misery.

Oh, and the line in the Monitor section : 'Option "SyncOnGreen"' does what exactly ? I've added it only recently, but found that it changes nothing I can tell.

Thanks in advance,

Iain Scurrah.



/etc/X11/xorg.conf :

Section "Module"
Load "dbe" # Double buffer extension
SubSection "extmod"
Option "omit xfree86-dga" # don't initialise the DGA extension
EndSubSection
Load "type1"
Load "freetype"
Load "glx"
Load "dri"
EndSection

Section "Files"
RgbPath "/usr/X11R6/lib/X11/rgb"
FontPath "/usr/X11R6/lib/X11/fonts/local/"
FontPath "/usr/X11R6/lib/X11/fonts/misc/"
FontPath "/usr/X11R6/lib/X11/fonts/75dpi/:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/100dpi/:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/Type1/"
FontPath "/usr/X11R6/lib/X11/fonts/TTF/"
FontPath "/usr/X11R6/lib/X11/fonts/cyrillic/"
FontPath "/usr/X11R6/lib/X11/fonts/75dpi/"
FontPath "/usr/X11R6/lib/X11/fonts/100dpi/"
EndSection

Section "ServerFlags"
EndSection

Section "InputDevice"
Identifier "Keyboard1"
Driver "kbd"
Option "AutoRepeat" "500 30"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "hu"
EndSection

Section "InputDevice"
Identifier "Mouse1"
Driver "mouse"
Option "Protocol" "IMPS/2"
Option "Device" "/dev/mouse"
Option "ZAxisMapping" "4 5"
Option "Emulate3Buttons" "no"
EndSection

Section "Monitor"
Identifier "C993"
HorizSync 30-95
VertRefresh 50-160
Option "DPMS"
Option "SyncOnGreen"
EndSection

Section "Device"
Identifier "Standard VGA"
VendorName "Unknown"
BoardName "Unknown"
Driver "vga"
EndSection

Section "Device"
Identifier "Radeon"
Driver "radeon"
Option "AGPMode" "4"
Option "AGPFastWrite" "on"
Option "EnablePageFlip" "on"
EndSection

Section "Screen"
Identifier "Screen 1"
Device "Radeon"
Monitor "C993"
DefaultDepth 24
Subsection "Display"
Depth 8
Modes "1600x1200" "1280x1024" "1024x768" "800x600" "640x480"
ViewPort 0 0
EndSubsection
Subsection "Display"
Depth 16
Modes "1600x1200" "1280x1024" "1024x768" "800x600" "640x480"
ViewPort 0 0
EndSubsection
Subsection "Display"
Depth 24
Modes "1600x1200" "1280x1024" "1024x768" "800x600" "640x480"
ViewPort 0 0
EndSubsection
EndSection

Section "ServerLayout"
Identifier "Simple Layout"
Screen "Screen 1"
InputDevice "Mouse1" "CorePointer"
InputDevice "Keyboard1" "CoreKeyboard"
EndSection

Section "DRI"
Mode 0666
EndSection

you could try to add the virtual line:

Depth 24
Modes "1600x1200" "1280x1024" "1024x768" "800x600" "640x480"
ViewPort 0 0
Virtual 800 600 (or whatever the new res is)
EndSubsection

Cheers, but that would give me a fixed desktop resolution.

Normally - at least in my experience - if change the resolution within Xorg, without restarting the server, it will give the same desktop resolution as screen resolution. I.e. going from 1600x1200 to 800x600 should give physcally (cm) bigger icons and text. That's not happening for me. If I use <ctrl>+<alt>+<numeric +> then the desktop changes size, but the screen resolution remains at 1600x1200. The text and icons remain the same size, but a smaller portion of my screen real estate is used. At 800x600, only one quater of my screen is being used, the other three quarters is just black.

It is a bit like the first LCD screens, they could display at one resolution only, if you requested a smaller resolution, then the desktop would appear with a unused border around it ...

I'm not quite sure what you are asking but I think you mean the DPI. When you change resolution things get to big or to small?

Anyway, you could set the DPI for you monitor to avoid this.

Just put the DisplaySize in the monitor section.

DisplaySize w_in_mm h_in_mm


You can either measure your screen or look it up at your monitors homepage, samsung or whatever. This will keep things the same size when you switch resolutions. Lots of people just pass dpi 96 to X, which is wrong becuase it assumes you monitor is a fixed dpi at any resolution.

Hmmm, my explanations seem to be as clear as mud! Doctored screen shots would be great - but I'm not allowed to post attachments.

I have a 19" monitor that is capable of 1600x1200. This is the normal resolution that I work at. At 1600x1200, the entire screen (19") is filled.

Sometimes, I want to change to a lower resolution (800x600) - either via the ctrl+alt+'num+', or via the 'Screen Resize and Rotate' program. When I do this, I want the new resolution to be shown using the whole monitor, ie 19" diagonal. Sadly, it doesn't happen, the new display only fills a quarter of the 19" - ie it is just over 5" diagonally, and it is located at the top right of the monitor screen.

Remember when you could have a virtual desktop (e.g. 2048x2048) that was bigger than the resolution of your monitor (eg 1024x768) ? You could scroll around the desktop - but showing only only a certain portion of the desktop at one time. I've got the opposite problem - when my desktop resolution (and desired screen resolution) is smaller than my standard screen resolution. At this time, I get a tiny desktop (800x600), but my monitor resolution remains at 1600x1200.

If you still don't understand, please mail me - my linuxquestions username at hotmail dot com. I'll send two tiny examples.

Thanks in advance,

Iain Scurrah.