> 
> 
> To sum up : this is an IBM A30p, with an "external" Radeon Mobility LY 
> (32 MB), and an 830MP instead of an 830M. The 830MP is common for both 
> IBM A30 and A30p models.
> 
> 

OK ! so you _do_ have an external graphic card (that's what looked unclear to me), 

for which AGP should work in the same way it does for other Intel chipsets...

So why not trying the little patch I attach below, which should make 
your stuff work, without breaking too much the i830 support for on-board 
adapters... The patch is for 2.4.16, but is likely to be applied easily 
on another recent kernel. Keep me informed...

Best regards
-- 
Nicolas Aspert      Signal Processing Laboratory (LTS)
Swiss Federal Institute of Technology (EPFL)