Izumi Tsutsui wrote:
>> device tree [after changes]:
>>   mainbus(root)  evbppc/evbppc/mainbus.c
>>    +-- cpu       cpu-depend-setup
>>         +-- plb  config_attach with cpu_attach_args
> 
> I think "cpu" in the device tree means CPU processor core,
> not microcontroller with peripherals, so plb should be
> attached (at least) at mainbus rather than cpu.

An embedded-cpu such as IBM PPC4xx has a processor core
and some other devices inside Processor(CPU).

> On the other hand, pseudo mainbus may be required
> to attach cpu and plb, IMHO.

If `cpu' device means a processor core, your opinion is right.

1-Processor machine:

  Processor(CPU): This is a root device.
   |
   +-- cpu (processor core)
   +-- plb
        |
        +-- opb
        :    |
        :    +-- com
        :    :

Is the above device-tree-image(thinking) ok?

-- 
Kind Regards,
--- shige
Shigeyuki Fukushima <shige@{FreeBSD,jp.FreeBSD,NetBSD}.org>