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Date: Tue, 29 Sep 2009 11:08:02 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 16/24] qdev hotplug: infrastructure and
	monitor commands.
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To: Markus Armbruster <armbru@redhat.com>
Cc: qemu-devel@nongnu.org

>>   /* This is a nasty hack to allow passing a NULL bus to qdev_create.  */
>> +static int qdev_hotplug = 0;
>> +
>
> I see the "nasty hack" part, but I don't see how qdev_create() accepts a
> null bus now:
>
>>   static BusState *main_system_bus;

The (existing) "nasty hack" comment belongs to the main_system_bus 
variable and should stay there of course to avoid confusion ...

>>       /* create device, set properties */
>>       qdev = qdev_create(bus, driver);
> [...]
>
> As far as I can see, all qdev_hotplug does is telling qdev_device_add()
> and qdev_create() that this is a hotplug.

Yes.

> What about something like:
>
> DeviceState *qdev_device_add(QemuOpts *opts, int hotplug)
> {
> [...]
>      if (hotplug&&  !bus->allow_hotplug) {
>          qemu_error("Bus %s does not support hotplugging\n",
>                     bus->name);
>          return NULL;
>      }
>
>      /* create device, set properties */
>      qdev = qdev_create(bus, driver);
>      if (hotplug) {
>          dev->hotplugged = 1;

I started that way.  Doesn't fly.  Not every device creation goes 
through qdev_device_add().  Thus you'll have to do this in 
qdev_create(), which in turn means that you would have to add a hotplug 
parameter to tons of functions just to pass it down to qdev_create ...

cheers,
   Gerd