I just bought a brand new Ultra-wide 21:9 LG 25UM58 monitor for my son.
Even on a Cauldron update, the monitor isnât recognized by drakx11 (and not found manually in the loooong list of LG monitors), nor is auto-detected in its plain definition as a plugân play generic 2560Ã1080 monitor, and it falls back to full-HD. Drakx11 doesnât even seem to support such 21:9 ratios (but only 4:3, 16:10 and 16:9).

It seems that 21:9 ratio definitions are not very well supported by X.org, at least by default in Mageia, even with NVIDIA proprietary graphic drivers.

It could be a limitation of the hardware (GeForce 9300 GE thru an HDMI port), but I donât think so.

I tried to generate a specific Modeline with this recipe Iâve found on the Net:
http://askubuntu.com/questions/138408/how-to-add-display-resolution-fo-an-lcd-in-ubuntu-12-04-xrandr-problem
Generating this:

Section "Monitor"
  Identifier "Monitor0"
  #Modeline "2560x1080_75.00"  294.00  2560 2744 3016 3472  1080 1083 1093 1130 -hsync +vsync
  Modeline "2560x1080_60.00"  230.00  2560 2720 2992 3424  1080 1083 1093 1120 -hsync +vsync
EndSection
Section "Screen"
  Identifier "Screen0"
  Device "DVI-I-0"
  Monitor "Monitor0"
  DefaultDepth 24
  SubSection "Display"
    Depth 24
    #Modes "2560x1080_75.00" "2560x1080_60.00"
    Modes "2560x1080_60.00"
  EndSubSection
EndSection

But still no success for nowâ¦