在 2013-03-19二的 09:05 +0000，Peter Maydell写道： > On 19 March 2013 00:55, li guang <lig.f...@cn.fujitsu.com> wrote: > > 在 2013-03-18一的 11:07 +0000，Peter Maydell写道： > >> I'm really dubious that this can or should be implemented by > >> adding methods at the device base class level. I don't think > >> real hardware works this way. > > > > and what it should be? > > > >> You could probably do power on/off > >> like this. Reset definitely shouldn't be done this way, and > >> suspend probably not either. > > > > AFAIK, reset is mostly power off then power on, > > The DeviceState method 'reset' simulates a power cycle. > On real hardware power-controller controlled reset is > more complicated and generally devices implement one > or more reset pins which can be asserted by the power > controller.
By now, it seems 'reset' callback only implemented as device status initialization, and I want to keep this, because, it's mostly the result power off/on. > > > suspend, of course is not supported by all devices, > > but, if system want to suspend, it have to let all devices > > aware this, and if the device support power suspend, it > > can do something specific(or just some with others, simple) > > I suspect this should involve more modelling of actual > control signals between the power controller and > the devices, not methods on the base class. > do we have to realize something like signals which are actually only some copper wires? I think we just emulate the real work, that is when some signals asserted, we just call corresponding method to do something by these embedded method, I want to let devices take care of power event(on/off/suspend/wakeup) themselves. > > I'm eager to get more comments and discussion. > > This idea simply based on system board design convention, > > I'm not saying a power chip has signals directly connected > > to all devices, I mean system board and its devices should > > have protocol to deal with power state changes. > > Hardware does it with signals, so should we. can these signals be viewed as the calling of corresponding methods?
