Boot failure with ppc64 port on iMacs G5

[tuxayo]

Hi again :)

I tried snapshots/2024-01-31/debian-12.0.0-ppc64-NETINST-1.iso

And was able to start booting from usb with:
boot usb0/disk@1:,\boot\grub\powerpc.elf
(typed in Open Firmware shell)
(usb0 is the top port)

Grub worked, and then I tried default install (the 1st option) and it
started loading during like 2 minutes.
And then it got stuck with some superposition of the messages
smp_core99_probe
and
the stuff before
DO-QUIESCE finisedBooting Linux via __start() @ 0x0000000002090000 ...

Full message of the two iMacs G5 ↓↓↓
https://transfert.facil.services/r/Ksfq_2VM9_#tDATBcLXzB0zkAEaiqm9gfLfsaXliVJ13rQxKUHgUmA=
https://transfert.facil.services/r/Zs1h1jEtb2#jufjxv6+1DfHnO3TSfhmYD+teOvY46sGClHyz7SiXd4=

Same when starting expert install.

Models: M9249 and M9845, see:
https://en.wikipedia.org/wiki/IMac_G5

Any hint of what might be the issue?

Cheers,

--
tuxayo