In order to add some features I had to build a new kernel for Kubuntu 6.06 on Apple iBook G4:
This new kernel hangs at bootup:

> calling quiesce
> returning from prom_init

The info I got so far refers to the grahics drivers settings:
Mine is ATI Mobility Radeon 9550, Chipset ATY, M12, Bus AGP

First of all, when selecting the current driver for Radeon it won't compile, selecting the old driver compiles alright.
Most of the other drivers also compile but it won't make sense of course and anyway hang at the same place at bootup.
BTW kernel 2.6.17.7-ubuntu; I tried 2.6.22.12 as well, some problem.

Anyone been facing similar problems? Any suggestions that might point me in the right direction?

Thanks in Advance!

I'm not familiar with the boot loader that you would use on a Mac computer. But if you have a configuration file similar to lilo.conf or menu.lst that lists a kernel line, compare the kernel options between your old boot entry and the new one. You may simply need to copy the old options to your new entry. When you create a new kernel, a new initrd file is created and there is a new boot entry to boot the new kernel. I wouldn't be surprised if a missing kernel option in the new entry is the problem.

Thanks jschiwal, I'm using yaboot. Not many options to set in yaboot.conf.
Nevertheless, comparing with something that works (the original configs) is always a good idea. So now I am compiling with exactly those configs (and waiting for the moment of thruth).