ppc 9500 boot problem

[musireco]

AT FIRST, YOU CAN REFER IN THE BEGINER INDEX WHERE I EXPLAIN THE PROBLEM.
RESUME:
Installing YDL 3.0.1 no problem...ok, I'm really happy.
Booting: bootx 1.2.2: at start up chose linux.
Yellow dog : problem with video driver aty match 64.

I want to try linux on this PPC!!!
I found an information about the apple open firmware...
With system disk, I can change parameters. It is the good way to resolve this aty problem or not?
If someone have an idea about that, i'll be very happy.
I don't realy now what to do with the boot parameters and perhaps I don't have to do that?
I don't now.
THE QUESTION ARE :

DID I NEED TO FIND SOLUTION WITH BOOTX OR WITH YELLOW DOG PARAMETERS?

DID NEED TO FIND SOLUTION WITH MAC OS BOOT(SYSTEM DISK AND OPEN FIRMWARE)?

Thanks if somebody can help me and the others who want's to put yellow dog on the same machine...

I'm new user, I don't now anything about comand line and programming..I only use softs with mac os since long time.