Restaurar las X y aceleración gráfica.

Como casi siempre, cada vez que actualizamos el kernel de nuestra distribución, se nos jode la animación 3D en el escritorio. Bien, mi caso es con una tarjeta gráfica ATI Radeon X550 y Ubuntu 10.04, y después de mucho leer y sin conseguir arreglarlo, di con la tecla. Os lo resumo aquí. Primeramente debeis instalar los drivers.

Es conveniente que vayais al modo texto (alt + ctrl + F1).
1. sudo /etc/init.d/gdm stop
2. sudo Xorg -configure
3. sudo cp xorg.conf.new /etc/X11/xorg.conf
4. sudo dpkg-reconfigure xserver-xorg
5. sudo reboot

Después de reiniciar, entramos en el modo gráfico.
instalamos mesa-utils: sudo apt-get install mesa-utils
y ejecutamos: glxinfo ó glxgears.

A mí como no me funcionaba, cada vez que ponia glxinfo me salia
X Error of failed request: BadLength (poly request too large or internal Xlib length error) Major opcode of failed request:...
Total, que no me funcionaba la aceleración 3D, y no encontraba nada por internet. Al final de casualidad instalé.
sudo apt-get install libgl1-mesa-swx11-dev


Y ya funciona la aceleración 3D perfectamente, igual que antes de actualizar el kernel.
Finalmente, para comprobar si os funciona la aceleración 3D:
$ glxinfo | grep direct
$ glxgears

Aquí os dejo el archivo xorg.conf por sí hay alguna duda.

Section "ServerLayout"
Identifier "X.org Configured"
Screen 0 "Screen0" 0 0
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection

Section "Files"
ModulePath "/usr/lib/xorg/modules"
FontPath "/usr/share/fonts/X11/misc"
FontPath "/usr/share/fonts/X11/cyrillic"
FontPath "/usr/share/fonts/X11/100dpi/:unscaled"
FontPath "/usr/share/fonts/X11/75dpi/:unscaled"
FontPath "/usr/share/fonts/X11/Type1"
FontPath "/usr/share/fonts/X11/100dpi"
FontPath "/usr/share/fonts/X11/75dpi"
FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
FontPath "built-ins"
EndSection

Section "Module"
Load "extmod"
Load "record"
Load "dbe"
Load "dri2"
Load "dri"
Load "glx"
EndSection

Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
EndSection

Section "InputDevice"
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "ZAxisMapping" "4 5 6 7"
EndSection

Section "Monitor"
#DisplaySize 300 230 # mm
Identifier "Monitor0"
VendorName "SAM"
ModelName "SyncMaster"
HorizSync 30.0 - 61.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection

Section "Device"
### Available Driver options are:-
### Values: : integer, : float, : "True"/"False",
### : "String", : " Hz/kHz/MHz"
### [arg]: arg optional
#Option "NoAccel" # []
#Option "SWcursor" # []
#Option "Dac6Bit" # []
#Option "Dac8Bit" # []
#Option "BusType" # []
#Option "CPPIOMode" # []
#Option "CPusecTimeout" #
#Option "AGPMode" #
#Option "AGPFastWrite" # []
#Option "AGPSize" #
#Option "GARTSize" #
#Option "RingSize" #
#Option "BufferSize" #
#Option "EnableDepthMoves" # []
#Option "EnablePageFlip" # []
#Option "NoBackBuffer" # []
#Option "DMAForXv" # []
#Option "FBTexPercent" #
#Option "DepthBits" #
#Option "PCIAPERSize" #
#Option "AccelDFS" # []
#Option "IgnoreEDID" # []
#Option "CustomEDID" # []
#Option "DisplayPriority" # []
#Option "PanelSize" # []
#Option "ForceMinDotClock" #
#Option "ColorTiling" # []
#Option "VideoKey" #
#Option "RageTheatreCrystal" #
#Option "RageTheatreTunerPort" #
#Option "RageTheatreCompositePort" #
#Option "RageTheatreSVideoPort" #
#Option "TunerType" #
#Option "RageTheatreMicrocPath" #
#Option "RageTheatreMicrocType" #
#Option "ScalerWidth" #
#Option "RenderAccel" # []
#Option "SubPixelOrder" # []
#Option "ShowCache" # []
#Option "ClockGating" # []
#Option "VGAAccess" # []
#Option "ReverseDDC" # []
#Option "LVDSProbePLL" # []
#Option "AccelMethod" #
#Option "DRI" # []
#Option "ConnectorTable" #
#Option "DefaultConnectorTable" # []
#Option "DefaultTMDSPLL" # []
#Option "TVDACLoadDetect" # []
#Option "ForceTVOut" # []
#Option "TVStandard" #
#Option "IgnoreLidStatus" # []
#Option "DefaultTVDACAdj" # []
#Option "Int10" # []
#Option "EXAVSync" # []
#Option "ATOMTVOut" # []
#Option "R4xxATOM" # []
#Option "ForceLowPowerMode" # []
#Option "DynamicPM" # []
#Option "NewPLL" # []
#Option "ZaphodHeads" #
Option "DRI" "true"
Option "XAANoOffscreenPixmaps" "true"
Identifier "Card0"
Driver "radeon"
VendorName "ATI Technologies Inc"
BoardName "RV370 [Sapphire X550 Silent]"
BusID "PCI:2:0:0"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
SubSection "Display"
Viewport 0 0
Depth 1
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 4
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 15
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection

Section "Extensions"
Option "Composite" "Disable"
EndSection

Section "DRI"
Mode 0666
EndSection