>I'd suggest NetBSD/mipsco, a modern NetBSD port for MIPS Computer
>RC3230 system.  It has fairly similar devices inside.  All of device
drivers
>which your machine has are already written by others in MI form or MD
>form.  So little hardship is expected before useful working devices.

Thank you for your comments - this is exactly the type of direction I was
looking for. Starting with as "clean" a port as possible can only help me
move forward. Your comments about the devices is reassuring, but I think I'm
quite "up against it" when it comes to the actual specifics of the I/O gate
array (ie: bus and DMA). I'm expecting to have to work this out by
disassembling parts of the native system...

>I'm personally interested in pmap module for the processor.  I have local
>pmap codes for MIPS and m88k which are too inmature to commit NetBSD.
>During the development efforts, I've learned much about NetBSD pmap
>logics.  Probably I would be able to guide you on the aspect.

That would be very helpful, I'm sure. Although I don't have much information
yet, the two major differences between the MMU setup on this system and the
MIPS architecture are: the CLIPPER has 2 MMU chips, one for data, one for
instructions, each of which has a 128-entry TLB, and memory is not segmented
by the system using high address bits as is the MIPS. I have no idea how
much impact this type of thing has on the pmap module yet - I've not looked
into that aspect of NetBSD at this time. Again, any comments you have are
invaluable.

>I could provide more details of porting, step-by-step and file-by-file
>explanations.   If you're a sort-of kernel guy and you have 
>not get touch with following two books, I recommend them highly.

I've done some work with the Linux kernel in the past, mainly with device
drivers, but I'm by no means an expert, and can use all the help I can get.
What would help initially would perhaps be a guide on where to begin - ie:
what part of the system is the key to getting the rest working?

>Uresh Vahalia, UNIX Internal, The New Frontier
>Curt Schimmel, UNIX Systems for Modern Architectures

I'll check those books out at some point - thank you.

Regards,
Pat Mackinlay