Re: [PATCH] Incorrect segment 0 initialization for PMAC G5

[Phileas Fogg <phileas-fogg%mail.ru@localhost>]

On 03/28/2013 01:22 AM, Christos Zoulas wrote:

> What specifically do you need? Do you have any questions?
>
> christos

Hi,
i'm a bit new to NetBSD hacking but not to the PowerPC architecture.
Recently i have got a PowerMac 11,2 G5 and wanted to run a BSD on it.
After some failed attempts to boot NetBSD on it, i decided to
take a closer look at the problems i'm having. And i have some
questions which could help me to understand what's going on.
So thanks in advance for your support.

My questions:

1. What is the purpose of options PMAP_NEED_FULL_MAPKERNEL and 
PMAP_NEED_FULL_MAPKERNEL in arch/powerpc/oea/pmap.c:pmap_bootstrap ?
I couldn't find any documentation on this and the kernel hangs after
enabling MMU if i don't disable this code.
I see that the first 256MB of RAM are mapped 1:1 in ofwoea_initppc,
so why do full kernel map again.

2. Why use a separate OFW pmap to be able to use OFW client-interface if we
can just use the kernel pmap and enter the OFW mappings into it.
I just did it on my NetBSD kernel and can call OFW client-interface
in kernel virtual-mode with no problems.

3. Currently i'm stuck in 
sys/arch/macppc/macppc/interrupts.c:init_interrupts because G5's U4 MPIC 
is not found.
Why does NetBSD require the interrupt controller to be initialized 
before configure process, why not use autoconf to autodetect interrupt 
controllers too.

4. The function ofwoea_initppc maps the OFW code+data at 0xff800000 to 
0x3fc00000. And that's not correct on my machine. On my G5 it's mapped
to 0x7fc00000.


Thanks for your time.


regards