On Thu, Feb 10, 2011 at 10:38:53AM +0000, Peter Maydell wrote: > This is the system diagram for the Versatile Express: > http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0447d/I1007683.html > I don't know what you'd want to claim is a "northbridge" there. > Basically there's an FPGA with a pile of devices in it, > and there's a test chip with the core and some other devices in > it. But from a modelling perspective this is all completely > irrelevant because regardless of where the hardware designer > put the devices, they're just devices at a particular point in the > memory map and with a particular set of interrupt wiring and so > on. I don't see the point in modelling a concept that has no > user-visible effects and doesn't actually make the model any > clearer or simpler. > Exactly. This is really the same with x86. The fact that some company put several devices on the same chip and gave it commercial name shouldn't govern our design. > > > A machine today is basically the northbridge, southbridge, plus a bunch of > > default components to make the virtual hardware useful. > > This doesn't really correspond to ARM boards I've looked at, > by and large (for instance there's no mention of the word "northbridge" > in the whole 3700 page OMAP3 TRM). PCs may be best modelled > that way, sure, but I don't think you can cram everything into that mould. > Even on x86 this model is falling apart. Memory controller moves to cpu. PCI controller will follow. > >> If you mean that you want machines to be implemented under the > >> hood as a single huge "device" you can only have one of that spans > >> the entire memory map, well I guess that's an implementation > >> detail. But conceptually machines really do exist, and we definitely > >> still want users to be able to say "I want a beagle machine; I want > >> a versatile; I want an n900". > > > An n900 is a very specific hardware configuration that is best represented > > by some sort of configuration file vs. something hard coded in QEMU. > > Yes, that's the whole point -- "machine" == "specific hardware > configuration". > > That's not getting rid of "machine", it's just saying "we should have > some custom scripting language to define them rather than doing > them in C". You still want, fundamentally, to be able to say > qemu-system-arm -M machinename > +1 -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
