Re: [Qemu-devel] [RFC 1/9] hostdev: introduce the infrastructure for host device model

[Paolo Bonzini <pbonzini@redhat.com>]

Il 27/03/2012 23:21, Zhi Yong Wu ha scritto:
>> Yes, that's correct.  Everything that uses PROP_PTR needs to become a
> But i didn't see that that stuff which uses PROP_PTR become a link in
> current QEMU code.

Yes, that's why I wrote "needs to become".  In order to use links, you
need two things:

* the target needs to have a canonical path (more on this below);

* the target needs to be QOMified.

Most PTR properties are pointers to devices, but devices so far don't
always have a canonical path so the conversion could not happen.  Others
are to CPUs, which are not yet QOMified.

>> link.  We cannot do that yet because devices do not yet have a canonical
>> path.
> Cannonical path means that it is one absolute path or partial path?

Canonical path means it consists exclusively of child<> properties.
Unlike the links, which form a graph, children form a tree so it's easy
to define a canonical naming of all objects.

>>>>> Moreover, -device has exposed network card info.
>>>>
>>>> ... this is extremely confused.  Each NIC device has a NIC-type
>>>> NetClientState.  If NetClientState is converted to QOM, all of its
>>> The original idea about -netdev QOM is to convert NetClientState to
>>> QOM, but now this idea seems to be changed.
>>
>> I cannot parse this at all.  You have not converted all of
>> NetClientState to QOM, have you?
> No. I am not sure if we need to convert all and we need to know what
> the benefit is.

We do.  You just cannot convert the same object half to QOM and half
not.  It leads to insanity.

>>>>> We hope that -netdev options info can be configurated or changed
>>>>> purely via QOM, not command line.
>>>>
>>>> Yes, but does it buy anything or it is just a nice exercise?
>>>
>>> buy anything? sorry, i don't understand this.
>>
>> What's the advantage?  Converting chardev would give hotplug.  What can
>> we do with a QOMified netdev that we cannot do now?
> It can be configurated or changed purely via QOM, this is one of the
> advantages by itself.

Sure, but what does it do better than netdev_add?

Note that the same holds for devices.  Anthony converted them as the
proof that QOM could deal with them, and that conversions could be done
in small steps.  But strictly speaking it was not necessary to convert
them to QOM; so far, conversion brought no substantial improvement.

> And I think that it should also give hotplug.

Hotplug of -netdev is already supported.

Paolo