Ubuntu8.10，9．04でXineramaを有効にするとXが起動しない

Quadro NVS 285とQuadro NVS 55/280 PCIの2つのビデオカードでクアッドディスプレイをしようとして，Xineramaを有効にすると，Xが起動できなくなって次のエラーが吐かれる

The display server has been shut down 6 times 
in the last 90 seconds. It is likely that 
something bad is going on. Waiting for 2 
minutes before trying again on display :0

原因は，まず，XineramaとXのglxモジュールが共存できないのと，8.10からデフォルトでglxモジュールが有効になるようになったからっぽい．だから，xorg.confで明示的にglxモジュールを無効にするようにすればいい

Section "Module"
    Disable           "glx"
EndSection

ビデオカードをまたいでも，カーソルが残ったままになって，常時二つのカーソルがみえるのは愛嬌
以下，xorg.conf全文．Moduleセクション以外は自動生成

# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings:  version 1.0  (buildd@palmer)  Sun Feb  1 20:21:04 UTC 2009

# xorg.conf (X.Org X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# Note that some configuration settings that could be done previously
# in this file, now are automatically configured by the server and settings
# here are ignored.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
#   sudo dpkg-reconfigure -phigh xserver-xorg

Section "ServerLayout"
    Identifier     "Default Layout"
    Screen      0  "Screen0" 0 0
    Screen      1  "Screen1" RightOf "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Module"
    Disable           "glx"
EndSection

Section "ServerFlags"
    Option         "Xinerama" "1"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "Monitor"
    Identifier     "Configured Monitor"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "EIZO L557"
    HorizSync       31.0 - 64.0
    VertRefresh     59.0 - 61.0
EndSection

Section "Monitor"
    Identifier     "Monitor1"
    VendorName     "Unknown"
    ModelName      "EIZO L557"
    HorizSync       31.0 - 64.0
    VertRefresh     59.0 - 61.0
EndSection

Section "Device"
    Identifier     "Configured Video Device"
    Driver         "nvidia"
    Option         "NoLogo" "True"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro NVS 285"
    BusID          "PCI:1:0:0"
EndSection

Section "Device"
    Identifier     "Device1"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro NVS 55/280 PCI"
    BusID          "PCI:5:4:0"
EndSection

Section "Screen"
    Identifier     "Default Screen"
    Device         "Configured Video Device"
    Monitor        "Configured Monitor"
    DefaultDepth    24
    Option         "AddARGBGLXVisuals" "True"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "TwinView" "1"
    Option         "metamodes" "DFP-0: nvidia-auto-select +0+0, DFP-1: nvidia-auto-select +1280+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Section "Screen"
    Identifier     "Screen1"
    Device         "Device1"
    Monitor        "Monitor1"
    DefaultDepth    24
    Option         "TwinView" "1"
    Option         "metamodes" "DFP-0: nvidia-auto-select +0+0, DFP-1: nvidia-auto-select +1280+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection