Hi,
You should try to install one of the Yaboot images to make sure there is no problem with your machine.That could be a check to perform... where is the last working yaboot image to be found?See: https://cdimage.debian.org/cdimage/ports/10.0/
If I install one of those images, yaboot gets installed and gets loaded at reboot, although boot finally fails with "unknown or corrupt filesystem" when loading the kernel. I used standard partitioning.
Maybe I am bitten by the fact that the installer partitioned ext4
root, but yaboot doesn't know about it. I will retry with a
separate /boot
I did a very minimal install, only system utilities, since there
are no "sid" repositories and the installer will try to find sid
even if a port mirror is given as URL.
Still, I think it is "proof enough", yaboot gets loaded - the same thing should happen to GRUB.
Also, this allowed me another important test: if "alt" is hit at boot, one hard disk is shown with a Penguin - this means that OpenFirmware sees the partition as bootable.
Does your iBook G4 run GRUB and does the same? I cannot access mine right now due to lockdown restrictions.
Riccardo