I've actually net booted a netbsd 1.6 kernel under PPC-BUG in prep  
mode on a Motorola MCP750.
This is a couple of years ago and I posted some minor changes to the  
1.6 kernel to this mailing list as there where a few issues to do  
with PCI I/O extents and the like.

Cheers,
Michael



On 11-Mar-06, at 1:45 AM, Tim Rightnour wrote:

>
> On 09-Mar-2006 Jochen Kunz wrote:
>> I did quite some work on ofppc about a year ago. I wrote PCI and ISA
>> attachments, pulled the whole interrupt code from port-prep to  
>> support
>> real interrupts, not just the fake OFW interrupt stuff. I have  
>> platform
>> dependent code for the Motorola PowerStack II (PReP with OFW) and the
>> IBM RS/6000 B50 and 43P-150 (7043-150). This code can be extended to
>> generic PReP and CHRP support.
>
> Ok.. I have some ideas here.. so bear with me.
>
> First.. from speaking with someone about the Powerstack II 3000, I  
> was told
> that it has three different firmware images available for it.   
> Firmworks OF,
> PPC-BUG, and ARC.  The PPC-BUG manual states that it provides  
> residual data.
> This means that if you can get PPC-BUG firmware on that machine,  
> and the manual
> wasn't lying, then you can most likely boot NetBSD/prep.
>
> Second.  The 7043-150 may or may not be a transitional machine like  
> the 7025.
> If it is, I believe it also provides residual, and can boot and run  
> prep.
>
> As for the B50.. I have no clue.. but stay tuned...
>
>> State is: IBM RS/6000 B50 and 43P-150 (with a bit of hacking maybe  
>> any
>> CHRP machine) detect all PCI and ISA devices but they hang when they
>> try to mount root as interrupts don't work. Similar for the  
>> PowerStack
>> II / PReP. Once I got the PowerStack II as far as mounting a MFS root
>> and emit packets on an add on ex(4) PCI card.
>
> Yeah.. this is the *exact* problem I had with the 7024.  What you  
> need to do is
> find the interrupt map.  I've seen OFW node dumps of the 7043-150,  
> and I know
> there is a node somewhere called "interrupt-map" or maybe its a  
> property of a
> node.  This (once decoded) will tell you exactly how to wire the  
> openpic.
>
> Also.. if the machine is prep bootable, then you have a second  
> wonderful
> opportunity.  You can use prep to understand the architecture of  
> the machine,
> and then make it work under ofppc.
>
>> If there is someone with interrest I can port my old patches to - 
>> current
>> and put them on the net. I don't wane commit it in this state as  
>> it will
>> fsck up port-ofppc. (Hmmm. Maybe I chould commit anyway. Maybe enough
>> people get anoyed to help me fix the remaining issues. ;-) )
>
> I'd be more than happy to help you with OpenPIC/MPIC issues.
>
> ---
> Tim Rightnour <root@garbled.net>
> NetBSD: Free multi-architecture OS http://www.netbsd.org/
> Genecys: Open Source 3D MMORPG: http://www.genecys.org/