drm module question.

[chy1013m1]

I've noticed something that makes me wonder..
I've got ATI binary driver setup and working great, gaming gives good framerate, etc.
However, I tried to update my drm kernel module, (I used liveCD2006.0 GRP install) After I emerged x11-drm, theres one new folder in /lib/modules/kernelversion/x11-drm with drm.ko and stuff in it.

what makes me wonder is, before I emerge x11-drm, without drm.ko direct rendering still works( no x11-drm folder), how come?
I thought every 3d driver needs a kernel module? does ATI binary provide its own?

[chy1013m1]

sorry for noobie question.. but the guides do not list specific dependencies for each module..
I am also confused as to which module loads which. can somebody outline the detail of the dependencies?
for modules like:

libdri.a
libdrm.a

also, compiling from DRI CVS gives libdri.*.so ? howcome a different extension?
thanks!