Re: [Qemu-devel] PPC emulation on Qemu

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> > What is OpenPPC standard ? So far, the most "standard" PPCs are
> > PowerMacs ;) 
> 
> Well, G4 Macs are close to OpenPPC standard, which is an open platform
> which has been described by IBM. I like it has a reference because it's
> nearly Macs and because AIX, MacOS (X I suppose) and Linux should be
> able to run on it.

You mean CHRP ? Hrm... AIX ? hehe, I wouldn't bet on that :) OS X
neither. But at least for OS X, you can write your own drivers,
like MOL does.

> Yes I know it can run Linux, but what I wanted to point is that (if I'm
> not wrong) it's not able to run any OS (ie AIX or pegasos or, why not
> (?), BeOS or AmigaOS) like a real machine would.

It could. All depends on which HW you emulate.

> I agree that MOL exactly intend to do this, and does it well, but I
> think qemu should really emulate the whole execution environment...
> 
> Does the OSI calls mechanism needs patched OS and/or firmware ?

It's an addition. MOL can run without it, it's just an optimisation
so you can load special drivers into the host OS to makes things
much faster / more useable.

On MacOS, it makes a lot of sense since the drivers can be provided
by the bootloader at boot or even in the ROM of some PCI cards, so
MOL can transparently get those loaded into the host operating
system when it's MacOS 9 or X.

Also, for OS X, MOL actually loads a special kext that patches the
kernel to remove it's use of MMU split mode, which isn't necessary
under emulation and actually very slow to emulate.

Ben.