On 7 January 2013 20:20, Anthony Liguori <aligu...@us.ibm.com> wrote: > Peter Maydell <peter.mayd...@linaro.org> writes: >> On 7 January 2013 19:10, Anthony Liguori <aligu...@us.ibm.com> wrote: >>> I think reset really ought to just be a bus level concept with >>> individual implementations for each bus. >> >> I'm not sure I really agree here, especially since QOM/qdev are >> moving away from the idea that there is a single bus tree and every >> device is on a single bus. > > I don't mean a BusState level concept, I mean a PCIBus concept. > > There is clearly such a thing as a PCI bus reset. In fact, there are > multiple types of PCI bus resets. There should be a PCIBus method that > calls out to PCIDevices on the bus. > > But that isn't something that should be fitted into generalized to a > BusState::reset method.
Ah, I see what you mean now -- yes, definitely. >> If we want to model reset properly we should model actual reset >> lines (and/or power-cycling). If we don't care we can continue with >> whatever fudge we like :-) > > Yes, and that's basically what qemu_system_reset() is. Of course, we > model it like everything is directly connected to a single power source > which is true 99% of the time. That's why we've gotten away with it for > so long. I think the bit that's most creaky here is what you do about devices that want to assert outgoing irq/whatever lines immediately on powerup. -- PMM
