Re: [Qemu-devel] [PATCH 09/16] Enable message delivery via IRQs

[Jan Kiszka <jan.kiszka@web.de>]

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Paul Brook wrote:
>> This patch allows to optionally attach a message to an IRQ event. The
>> message can contain a payload reference and a callback that the IRQ
>> handler may invoke to report the delivery result. The former can be used
>> to model message signaling interrupts, the latter to cleanly implement
>> IRQ de-coalescing logics.
> 
> I don't like this. qemu_irq is a level triggered interface. Redundant calls to 
> qemu_set_irq should (in principle) be a no-op.  If you want message passing 
> then IMO you should be using something else.

I think we all now agree that we need some extension to the qemu_irq
interface to realize clean irq de-coalescing.

Returning a delivery code was proposed several times but always
rejected. Blueswirl brought up that message passing can model this as
well and that it has additional use for sparc. So I followed this
suggestion, specifically due to the added value and the absence of
concerns by other parties. Now, after spending yet another "few" hours
on this series, you raise a new concern. Wouldn't it be possible to do
this during the design discussion?

OK, what is your proposal now for an IRQ de-coalescing framework?

Jan


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