Re: [Qemu-devel] support for Freescale MPC8xx (850/860) processors/platforms

[Brendan Simon (eTRIX)]

On 9/08/11 12:12 AM, Benjamin Herrenschmidt wrote:
> On Mon, 2011-08-08 at 15:57 +0200, Alexander Graf wrote:
>>> Anyone working on Freescale MPC8xx (embedded PowerPC) processors ??
>>>
>>> I'm trying to ascertain if the MPC8xx (MPC850) processors are
>>> supported, and if not, how much effort would be required to get it
>>> working.
>> I'm not aware of anyone working on MPC8xx CPU support. In fact, I
>> don't really know what they look like - I guess they're 601 derived? 
>>
>> Ben, any idea how much different 8xx is? 
> Gothic horrors :-)
>
> They have an MMU of their own. SW loaded TLB but different from anything
> else. They have a lot of other "quirks" too.

I know, I know, the processor is over 10 years old and I'd thought I'd
left it behind over 5 years ago, but I'm now working with it again ....
sigh.

What I am trying to do is run (emulate) an existing binary image on QEMU
so that I can do some accelerated system testing.  The images are S19
files programmed into flash that have an embedded RTOS (ThreadX) and a
networking stack (Interniche).

Anyhow, it sounds like I would have to add support for this processor,
so I'm trying to gauge how much work would be involved.

Is it a lot of work, or is it a matter of filling out some existing
stubbed out functions ??

Do I need to emulate all the hardware right down to the register level. 
The MPC850 has a lot of registers for configuring itself, the CPM
(Communications Processor Module -- a separate RISC co-processor for
comms), etc.

There seems to be better support (complete ??) for the MPC82xx (8250,
8260, etc) processors which have a G2 core an enhanced CPM.
Are there MPC82xx platforms supported in QEMU that I could use as a
basis to add support for MPC8xx platforms ?? 
Is there support for the SCCs and SMCs (part of CPM) for MPC82xx that I
can reuse for the MPC8xx ??

Where should I start (assuming the task is not horrific) ??

Thanks for any insight or suggestions.
Brendan.