For all of you that like to do things the hard way:
Getting 3D for your ATI Radeon card in LFS 
- Kernel 2.6.15 (with agp and DRM configured)
- Fresh LFS install
- Xorg 6.8.2 (By BLFS)
- Driver (either proprietary fglrx or r300_dri)
Probably not needed (and might even interfere!) Please verify and edit if possible.
- Mesa-6.4.1 (leftovers after failed attempt at installing r300_dri)
After browsing ATI's homepage for drivers I decided to use the installer-package (version 8.20.8), as I didn't have any easy way to convert rpms into tarballs.
If you decide to use the installer provided by ATI, make sure you don't have any libGL.so.* lying around in /usr/X11R6/lib before running the installer binary. It appears to rename installed files rather than overwriting old. Move any existing just to be safe:
mv /usr/X11R6/lib/libGL.so* /root/old_libGL
Run the installer, it does some checks and then opens a graphical point-and-clickety install window. Follow instructions and install the correct driver. Maybe it works now already? Never has for me, so I'll continue..
After the installer exits you should have a directory /lib/modules/fglrx/build_mod with a script "make.sh" to re-build the fglrx driver. Now for kernel 2.6.15 with fglrx 8.20.8 you'll need to apply a patch for avoiding errors of:
Bad page state at free_hot_cold_page
If the script complains about not being run from a real console, you could try to hack it a bit to go on anyway.
if [ $? -ne 0 ]; then echo "You arent running in a 'login shell'." echo "Please login directly from a console" echo "or use 'su -l' to get the same result." exit 1 fi
and delete the line with 'exit 1' to get past that annoyance. Run it to build the modules. Then change to the parent directory and run "make_install.sh", hack as needed. This installs the kernel module and it's conterpart in /lib/X11R6/modules/
Finally, when all of this is done, you might need an old version of libstdc++ check it by typing:
linux-gate.so.1 => (0xffffe000) libm.so.6 => /lib/libm.so.6 (0x408a5000) libstdc++.so.5 => /usr//lib/libstdc++.so.5 (0x408c7000)
Since I had only version 6 on my system I also installed version 5 to make fglrx happy.
Alternatively, setting LIBGL_DEBUG might also reveal old libstdc++ dependencies.
run fglrxconfig, answer a lot of questions, start X and pray.
Good luck! /Jeol
(...think I forgot somthing, hm.)
Read the log, look for errors (EE)
cat /var/log/Xorg.0.log | grep EE