ATI Mobility Radeon X300
Use Driver "radeon" in the xorg.conf file - it works at least for xorg 6.8.2, maybe older versions too. Currently (as of xorg 6.8.2) this will only give you 2D-acceleration, though. To enbable 3D acceleration as well you need to use the binary ATI driver fglrx.
Display on the internal LCD works as long as you set the monitor settings correct.
External VGA port
There are known problems. The driver from ATI turns off the switching between internal and external port.
To make switching with, use the "vesa" driver built into X.org instead of the ATI or "radeon" drivers. This loses acceleration and some capabilities.
Alternatively, start X without an external monitor, and then connect the external monitor. Both displays will be active, and cannot be switched off until you exit X. Note that if the external monitor is connected when X starts, the LCD will be deactivated and you will need to restart X. To have a reasonable refresh rate on the external monitor (the default is the LCD's 50Hz), use the following in /etc/X11/xorg.conf:
Section "Device" Identifier "Videocard0" VendorName "Videocard vendor" BoardName "ATI Radeon Mobility X300" Driver "radeon" Option "DynamicClocks" "on" Option "MergedFB" "on" Option "CRT2Hsync" "50-75" Option "CRT2VRefresh" "30-82" EndSection
(Tested wth Fedora Core 4 on ThinkPad T43).
See also the related discussion about Additional options for the radeon driver.
S-Video port (TV-out)
Linux support status is unknown.
Proprietary ATI driver
The fglrx driver adds 3D acceleration.
Linux kernel Framebuffer driver
radeonfb might cause problems with hardware acceleration under X on some systems, vesafb and vesafb-tng on the other hand has been reported to work just fine.
Clock rates, voltage and power
|Mode||core freq||memory freq||voltage||idle||3DMarks (Windows, 1600x1200, LCD only)|
|Performance||300||230 MHz||1.15V||2.98 W||8.28 W|
|Balanced||183||210 MHz||1.00V||1.71 W||3.88 W|
|Battery||120||105 MHz||1.00V||1.61 W||2.74 W|
|Mode||core freq||memory freq|
Experimentally, the difference between the Performance and Battery settings under Linux with DynamicClocks enabled is roughly 0.3W and 3-4 degrees in GPU temperature on a ThinkPad T43. Further frequency reduction leads to display flickering or corruption.
ThinkPads this chip may be found in