Re: [Qemu-devel] [PATCH 00/15] qdev: make reset semantics more clear and consistent, reset qbuses under virtio devices

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jan 09, 2013 at 10:33:37AM +0100, Paolo Bonzini wrote:
> Il 07/01/2013 20:10, Anthony Liguori ha scritto:
> > Paolo Bonzini <pbonzini@redhat.com> writes:
> > 
> >> After discussion with mst on the topic of resetting virtio devices,
> >> here is a series that hopefully clarifies the semantics of bus and
> >> device resets.
> >>
> >> After this series, there are two kinds of resets:
> >>
> >> 1) device-level reset is the kind of reset that you get with a register
> >> write on the device.  It will clear interrupts and DMAs among other things,
> >> but not any bus-level state, for example it will not clear PCI BARs and
> >> other configuration space data.  It is done with qdev_reset_all.
> >>
> >> 2) bus-level reset is the kind of reset that you get with a register
> >> write on the device that exports the bus (including triggering a device-level
> >> reset on the device that exports the bus).  It will do a device-level
> >> reset on the child, but also clear bus-level state such as PCI BARs and
> >> other configuration space data.  It can be triggered for all devices
> >> on a bus with qbus_reset_all.  There is still no API for a bus-level
> >> reset of a single device (like PCI FLR), this can be added later.
> > 
> > I don't really understand this dual abstraction.  I suspect it's
> > overgeneralizing something that's the result of poor modeling.
> 
> 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?
> 
> Paolo

I'm not sure what would you like to change with PCIDevice.

-- 
MST