My chipset is VIA P4X266A .
Yesterday, I had the idea to "insmod agpgart option try_unsupported=1" ... or something like that and after that I started the X server ... and surprise ... the AGP works. (I saw it /var/log/XF86Config.0.log "AGP: Successfully initialased" and again in /proc/driver/nvidia/agp/status "AGP:4x .... ")
So , I don't know what's the conclusion ... my chipset is not supported or is t new and there is no driver for it yet ...
Thank you for helping me !