Re: [Qemu-devel] [PATCH v2] sysbus: add irq_routing_notifier

[Paolo Bonzini <pbonzini@redhat.com>]

On 27/04/2015 14:20, Eric Auger wrote:
> On 04/27/2015 12:39 PM, Paolo Bonzini wrote:
>>
>>
>> On 27/04/2015 10:26, Eric Auger wrote:
>>>>> One of my long term goals is to try and get rid of sysbus IRQ
>>>>> abstraction completely in favor of just qdev gpios. This means
>>>>> features that apply to GPIOs automatically apply to IRQs and vice
>>>>> versa. Can your notifier hook be pushed up to the qdev GPIO level to
>>>>> make it more globally usable and avoid a new feature to sysbus IRQs?
>>> Yes sure, I am going to put the notifier in DeviceClass then.
>>
>> I've thought too about this, and I'm not sure about it.
>>
>> It would mean you have to pass the gpio name (e.g.
>> SYSBUS_DEVICE_GPIO_IRQ) to the hook, and in the case of sysbus IRQs this
>> would leak the SYSBUS_DEVICE_GPIO_IRQ abstraction to the implementors of
>> the hook.
> Hi Paolo,
> 
> Currently my notifier has the following proto:
>     void (*connect_gpio_out_notifier)(DeviceState *dev, qemu_irq irq);
> 
> It is sufficient for my need.
> 
> is it really mandated to pass other qdev_connect_gpio_out_named args,
> ie. name & n?

It's an ugly situation.  If you look at qdev_connect_gpio_out_named, it
is really a thin wrapper around object_property_set_link.  Just like
Peter wasn't too happy with changing sysbus_connect_irq, the same
objection would apply here.  Callers of object_property_set_link should
call the notifiers, not just those that use qdev_connect_gpio_out_named.

This is why I originally asked you to look into using the check callback
instead.

This is why I think it's better to keep the sysbus patch.

Paolo