A file /etc/X11/XF86Config-4 produced by 'Xconfigurator --preferxf4' has entries for Displays with a depth of 32 even if such depth is not used by XFree86 4.0. Michal michal
It would default to 24 bpp, and some drivers under XFree 3.3.x use both or just one(which varies...). I've disabled it for XFree4 FTTB in CVS, which will show up in Rawhide at some point (no RPM has yet been built, though)
Er... drivers from 3.3.x will have a hard time trying to use XF86Config-4. It is a minor quibble but I have seen people deeply confused by smaller things that. It is true that with 3.3.x some driver/cards combos _require_ 32 bit depth, and 24 bit will not work at all, but the beef was not about THAT configuration file.