Re: [Qemu-ppc] [PATCH 1/7] pci: add MPC105 PCI host bridge emulation

[Hervé Poussineau]

Alexander Graf a écrit :
> On 05/03/2013 07:57 AM, Hervé Poussineau wrote:
> > Alexander Graf a écrit :
> > > Am 02.05.2013 um 22:08 schrieb Hervé Poussineau <address@hidden>:
> > >
> > > > Non-contiguous I/O is not implemented.
> > > >
> > > > There is also somewhere a bug in the memory controller, which means
> > > > that some real firmwares may not detect the correct amount of memory.
> > > > This can be bypassed by adding '-m 1G' on the command line.
> > > >
> > > > Add x-auto-conf property, to automatically configure the memory
> > > > controller at startup. This will be required by OpenBIOS, which
> > > > doesn't know how to do it.
> > >
> > > Why not teach it? I'd prefer to see that logic in firmware.
> >
> > Me too, but I'm not confident enough in my capabilities to do it.
>
> Huh? Why not? Most of the device initialization code in OpenBIOS happens 
> in C, so you don't even have to touch Forth code :).
>
> > Autoconfiguration is only in one place of the code, so I think it can 
> > be removed easily once OpenBIOS has this logic.
>
> I'd prefer if we could come up with a clean model from the start. It 
> really shouldn't be hard at all.

I thought that for all other usages of OpenBIOS in QEMU, RAM was 
supposed to be available as soon as machine was powered on.

However, I checked OpenBIOS code:
One of the first things done in arch/ppc/qemu/start.S is to copy the 
exception vectors. So, I should add code before it to detect memory 
controller, detect ram size and configure memory controller?
It seems quite a bit of code.
Do you have an example of how to do it for another memory controller, so 
I can adapt the code?

Regards,

Hervé