Re: [KVM PATCH v2 2/2] kvm: add support for irqfd via eventfd-notification interface

Avi Kivity
2009-04-28T11:06:19Z

Gregory Haskins wrote:
>>>> But eventfd_signal basically marries us to eventfd.
>>>>
>>>>
>>> Well, only if we expect the fd to have eventfd semantics. There are
>>> advantages to doing so, as we have discussed, because things like AIO
>>> can polymorhpically signal an interrupt without even knowing whats
>>> behind the eventfd. But this isn't a strict requirement to support
>>> AIO. Really all we need is a way for both kernel and userspace to
>>> signal. Perhaps I should export an "irqfd_signal()" function from kvm,
>>> which today will map to eventfd_signal(), and tomorrow to ??. I don't
>>> think using f_ops->write() is an option for in-kernel signaling, so we
>>> need some kind of interface here.
>>>
>>> Does that sound reasonable?
>>>
>>>
>> irqfd_signal() ties the user of irqfd to kvm. I want this user to be
>> independent of kvm; it should work with eventfd, kvm's eventfd
>> lookalike (if we move away from eventfd) or pipes.
>>
>
> So what is your proposal for such interface?
>
>

->write().

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.