On Thu, Jan 10, 2013 at 08:14:43AM -0600, Anthony Liguori wrote: > Peter Maydell <peter.mayd...@linaro.org> writes: > > > On 10 January 2013 12:12, Paolo Bonzini <pbonz...@redhat.com> wrote: > >> Il 10/01/2013 12:59, Peter Maydell ha scritto: > >>>>>>> >>> > It's possible. I'll move the SCSI bus away from qdev reset. > >>>>>>> >>> > Anthony/Michael, can you help doing the same with PCIDevice? > >>>>>>> >>> > And > >>>>>>> >>> > perhaps Peter and Andreas with sysbus? > >>>>> >> What does it even mean to reset a sysbus? Do we do it anywhere? > >>>>> >> (it looks like vl.c does, just as a shortcut so memory mapped devices > >>>>> >> get their reset hooks called?) > >>> So how should it work instead? I kind of feel like all qdev devices should > >>> get their reset hook called on machine reset, regardless of bus [since > >>> it's > >>> modelling power cycling the whole system], but would that break > >>> something? > >> > >> It's just an implementation detail. Right now we have a common > >> callback. The idea is to give each bus its own callback. In the case > >> of sysbus it would just call a method; for PCI it would reset some > >> configuration and then call a method; for SCSI there is no need to call > >> a method at all; and so on. > > > > But machine reset shouldn't call bus specific PCI or SCSI reset > > methods -- we've just effectively yanked the power to the VM > > so everything should just reset as if it was freshly constructed. > > > > A bus-specific reset method would be for buses where the bus > > itself has some sort of guest-triggerable reset (by prodding the > > chipset, for instance). > > The challenge is how we go from what we have to what we want. > > Right now we have DeviceState::reset. This is used both as a soft and > hard reset. > > What I would propose is that we: > > s/DeviceState::reset/DeviceState::hard_reset/g > > Then introduce PCIDevice::soft_reset. We can convert the PCI layer to > call soft_reset() instead of hard_reset. > > Over time, it would be great if we could find a way to implement > hard_reset in terms of device destruction/recreation but we're not there > yet. > > I think the reset/hard_reset rename can be done via sed mostly. > > Would this solve the bug that you're trying to fix Michael/Paolo? > > Regards, > > Anthony Liguori
I don't think we need a rename to fix a specific bug. The bugs Paolo found can be fixed in virtio and virtio-scsi. > > >> In addition, navigating the qdev tree should be explicit in the methods. > >> It will not happen anymore via the "magic" qdev_reset_all. > > > > *Something* has to say "call reset for every qdev object in the > > system", surely? > > > > -- PMM
