Re: [Qemu-devel] MPC5200 + BestComm support in QEMU

[Alexander Graf]

On 23.08.2011, at 09:52, address@hidden wrote:

> 
> Hi, 
> 
> I'm Steve, an embedded software developper for Bombardier Transportation 
> Canada. We use the MPC5200 for most of our onboard computers inside train 
> control systems. To enhance our SW engineering process, we would like the 
> emulate the MPC5200 processor using QEMU, an open source software CPU 
> emulator. This software supports the MPC5200 CPU emulation. 

Well, Qemu can emulate a 603e reasonably well. The MPC5200 is 603e + soc 
devices. And I'm fairly sure we don't implement those :)

> However, the network interface is handled with the BestComm DMA engine and it 
> seems very difficult to simulate this co-processor with our current knowledge 
> level. In that sense, I would like to know if someone was able to emulate 
> correctly the MPC5200 with the BestComm DMA using QEMU software? 

The PPC device emulation is fairly limited when it comes to any peripheral 
devices that are not the actual core. And even the core emulation is lacking at 
times :).

So I'm fairly sure there is no emulation support for the BestComm DMA engine. 
Speaking of which - what exactly is this engine supposed to do? What devices 
talk to it? You also need to have the devices using the DMA engine be 
implemented, right? So you need the DMA engine plus the network interface?

What you could do is try to get decent specs of all of the devices that you 
need implemented and get someone to just write emulation code for them. 
Fortunately, you don't need to start off doing CPU emulation, as that's covered 
by the awesome open source nature of Qemu - someone else did it before you. But 
as far as this specific device goes, I think you really need to implement it 
yourselves.

That said, I'd gladly look at patches implementing those parts (provided I can 
also check-compare them with the specs) and if the device emulation is useful 
to anyone outside of your company, I'll also gladly pull them into the tree.


Alex