Today I got my new workstation at work, a nice P4 3Ghz in a Shuttle X-PC barebone with 1G of ram, 160GB SATA disk and a Asus A9250/TD (ATI Radeon 9250/9200PRO) to drive the 2 17" IIyama ProLite E435S TFT Screens. One screen is connected with DVI and the other screen with normal HD15 VGA cabling.

However I only got cloning the two screens to work on Linux. Running Windows XP with two independent screens worked flawlessly. So I ofcourse went out investigating how to get this working:

I got it working with a single screen using the stock radeon driver that's with XFree86 4.3 and with the ATI Catalyst Drivers for Linux. However dualhead cloning is something I only got working with the radeon drivers. But no xinerame or independent dualhead :(

There are some thing we should point out about the 9250. It's actually 2 cards in one as there are two VGA controllers to be found when one lists the PCI bus. One with ChipID 0x5960 and one with 0x5961, they sit on the same PCI bus.

Here is a post on a mailinglist about one guy using it as a single head solution with the free driver (which I also got working).

The following site has some hints on getting the card working and doing 3D acceleration, however I'm not interested in that.

The ATIRadeon Wiki entry points to MergedFB for doing dualhead support with all kinds of acceleration, but this option is not available in the XFree86 version I'm running currently so I want to avoid this solution until I have no other choice.

The following thread on debian-user-german explains the same problem as I have, let's dive in:
 - Replies on this thread point to debian packages at  http://people.debian.org/~daenzer/dri-trunk-sid/ that should do the trick, but as my workstation is currently turned off I can't try them out. Also this setup does Digital Flatpanel in laptop and CRT. I need DVI and CRT. However the enlisted config looks working to me, so I should try that setup tomorrow.

This thread looks promising. But still let's continue collecting more articles.

The linuxquestions Wiki also has an article about Dualhead on Linux. But the stuff here didn't seem to help me this afternoon.

And we got a winning configuration, it seems my problem lay in the following statement

        Option          "CloneMode" "OFF"

It seems the default for this is On, which ofcourse is not the wanted behaviour. Here is the complete configuration I am using now, remember that this config does NOT SUPPORT DRI, because of xinerama is enabled, the MergedFB option is not yet available in my version of XFree86.

Section "Module"
        Load    "GLcore"
        Load    "bitmap"
        Load    "dbe"
        Load    "ddc"
        Load    "extmod"
        Load    "freetype"
        Load    "glx"
        Load    "int10"
        Load    "record"
        Load    "speedo"
        Load    "type1"
        Load    "vbe"
EndSection

Section "InputDevice"
        Identifier      "Generic Keyboard"
        Driver          "keyboard"
        Option          "CoreKeyboard"
        Option          "XkbRules"      "xfree86"
        Option          "XkbModel"      "pc104"
EndSection
Section "InputDevice"
        Identifier      "Configured Mouse"
        Driver          "mouse"
        Option          "CorePointer"
        Option          "Device"                "/dev/psaux"
        Option          "Protocol"              "ImPS/2"
        Option          "Emulate3Buttons"       "true"
        Option          "ZAxisMapping"          "4 5"
EndSection

Section "Device"
        Identifier      "Radeon0"
        Driver          "radeon"
        VendorName      "ATI Technologies Inc"
        BoardName       "Radeon Mobility M7 LW [Radeon Mobility 7500]"
        BusID           "PCI:1:0:0"
        Screen          0
        Option          "AGPMode" "4"
        Option          "MonitorLayout" "TMDS , CRT"
        Option          "CloneMode" "OFF"
        #Option          "CloneHSync" "75"
        #Option          "CloneVRefresh" "75"
EndSection
Section "Device"
        Identifier      "Radeon1"
        Driver          "radeon"
        VendorName      "ATI Technologies Inc"
        BoardName       "Radeon Mobility M7 LW [Radeon Mobility 7500]"
        BusID           "PCI:1:0:0"
        Screen          1
        Option          "MonitorLayout" "TMDS, CRT"
        Option          "CloneMode" "OFF"
EndSection

Section "Monitor"
        Identifier      "Interner Monitor"
        #HorizSync      60
        #VertRefresh    75
EndSection

Section "Monitor"
        Identifier      "Externer Monitor"
        #HorizSync       60
        #VertRefresh     75
EndSection

Section "Screen"
        Identifier      "Default Screen"
        Device          "Radeon0"
        Monitor         "Interner Monitor"
        DefaultDepth    24
        SubSection "Display"
                Depth   24
                Modes   "1280x1024"
        EndSubSection
EndSection

Section "Screen"
        Identifier      "External Screen"
        Device          "Radeon1"
        Monitor         "Externer Monitor"
        DefaultDepth    24
        SubSection "Display"
                Depth   24
                Modes   "1280x1024"
        EndSubSection
EndSection

Section "ServerLayout"
        Identifier      "Default Layout"
        Screen          0 "Default Screen" 0 0
        Screen          1 "External Screen" LeftOf "Default Screen"
        InputDevice     "Generic Keyboard"
        InputDevice     "Configured Mouse"
        Option          "Xinerama" "true"
EndSection