Re: Changing ibm4xx device tree.

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

In article <445B48F8.10609%netbsd.org@localhost>
shige%netbsd.org@localhost wrote:

> There are two points on my plan.
> Point 1. What is a better root device?
> Point 2. PLB is a Processor *Local* bus inside CPU.
>          Plb should be attached after attaching cpu.
>          This is a feature of *embedded* cpu

The device tree should refrect logical structure
of devices, not physical one, I think.
I.e. even if the device bus is located in the same
core in the chip, it doesn't matter.
(consider how HT CPU is configured)

> I have neither multi-core 4xx nor 4xx multiprocessor system.
> If there are a 4xx multiprocessor system, what is root device?
> Root device is plb0(Processor *Local* Bus) for cpu0?
> Or is plb1 for cpu1?

Such multicore microcontroller will have two or more
processor cores but only one peripheral bus, so
attaching peripheral bus under cpu (which is logical one)
is not appropreate. I think that's the point simonb said.

If we have to attach cpu under some rootbus, maybe
it's better to have some pseudo bus like mainbus,
but I wonder if cpu have to be attached during
autoconf.
---
Izumi Tsutsui