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

[Paolo Bonzini <pbonzini@redhat.com>]

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