hw/ppc: Deprecate 405 CPUs

The ref405ep machine is scheduled for removal in QEMU 10.0. Keep the
405 CPU implementation for a while because it is theoretically
possible to model the power management (OCC) co-processor found on the
IBM POWER [8-11] processors.

Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Message-ID: <20250204080649.836155-4-clg@redhat.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

docs/about/deprecated.rst

@@ -266,6 +266,15 @@ in the QEMU object model anymore. ``Sun-UltraSparc-IIIi+`` and
 but for consistency these will get removed in a future release, too.
 Use ``Sun-UltraSparc-IIIi-plus`` and ``Sun-UltraSparc-IV-plus`` instead.
 
+PPC 405 CPUs (since 10.0)
+'''''''''''''''''''''''''
+
+The PPC 405 CPU has no known users and the ``ref405ep`` machine was
+removed in QEMU 10.0. Since the IBM POWER [8-11] processors uses an
+embedded 405 for power management (OCC) and other internal tasks, it
+is theoretically possible to use QEMU to model them. Let's keep the
+CPU implementation for a while before removing all support.
+
 System emulator machines
 ------------------------