Matt's Blog - aka DarwinsTheory

I've been running dual screens for years and sure as hell wasn't going back to one...!!

My machine was running a ATI X800 video card which at the time was pretty kick ass... Even now most games run in the 50-90fps mark which is very acceptable. So decided I'd try and get dual screens with acceleration support working... what a pain in the ass..! I did finally get it working but found that I ATI doesn't work with Beryl when you get over 2048 resolution in any direction.. my dual screens are 1650x1050 total 3360x1050 and therefore after all the pain wouldn't work... I finally ditched the card and got a 7600GT and got it all working in about an hour.. dual screen, full 3D support and Beryl... Linux and ATI.. not a good call.

Here's my notes.

ATI video card and dual screens

Two monitors and ATI video card... open source drivers ended up being waaaay easier to get working and using MergeFB to span the monitors seems to work well. No luck with the enhanced desktop as my resolution with combined monitors is 3360x1050 and apparently around 2000 is the limit.. DOH

Basically the binary drivers (the ones direct from ATI) would install but I could never get acceleration working.... if you don't intend to play games or use the enhanced desktop effects it doesn't really matter.

Here is the instructions on how to setup the open-source driver and enable dual desktops.

https://help.ubuntu.com/community/RadeonDriver

Here is the relevant sections of my working xconf.org

Section "Device"

Identifier "Generic Video Card"

Driver "ati"

BusID "PCI:1:0:0"

#Option "UseFBDev" "true"

#Option "XAANoOffscreenPixmaps" "true"

Option "UseFBDev" "false"

Option "BusType" "PCI" #Weird but apparently there is a bug in the current version so this is needed even though my card is AGP

Option "MergedFB" "true"

Option "MonitorLayout" "TMDS,CRT"

Option "CRT2Hsync" "30-65"

Option "CRT2VRefresh" "50-75"

Option "OverlayOnCRTC2" "true"

Option "CRT2Position" "LeftOf"

Option "MetaModes" "1680x1050-1680x1050 1680x1050"

Option "MergedXineramaCRT2IsScreen0" "false"

Option "MergedXinerama" "on"

# Performance Settings

Option "AGPMode" "8"

Option "AccelMethod" "XAA"

Option "ColorTiling" "on"

Option "EnablePageFlip" "true" #only works with accelmethod "XAA"

Option "AccelDFS" "true" #seemed to speed things up using EXA acceleration

Option "DMAForXv" "true" #This can speed up movie playback but can in rare cases case instability

Option "GARTSize" "64" #This is the size of the "GART" that xorg will use.

EndSection

Section "Screen"

Identifier "Default Screen"

Device "Generic Video Card"

Monitor "Generic Monitor"

DefaultDepth 24

SubSection "Display"

Depth 24

Virtual 3360 1050

EndSubSection

SubSection "Display"

Depth 24

Modes "1680x1050"

EndSubSection

EndSection

Section "ServerLayout"

Option "AIGLX" "true"

Identifier "Default Layout"

Screen "Default Screen"

InputDevice "Generic Keyboard"

InputDevice "Configured Mouse"

InputDevice "stylus" "SendCoreEvents"

InputDevice "cursor" "SendCoreEvents"

InputDevice "eraser" "SendCoreEvents"

EndSection

Section "DRI"

Mode 0666

EndSection

Section "Extensions"

Option "Composite" "Enable"

EndSection

NOTE: After many hours I finally worked out you can't get Beryl running with my ATI card so ditched it on the weekend and bought a nvidia 7600GT and had dual screens and Beryl running within an hour...!

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