Re: [PATCH 05/24] compatfd is included before, and it is compiled unconditionally

[Juan Quintela <quintela@redhat.com>]

Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Sep 22, 2009 at 03:25:13PM +0200, Juan Quintela wrote:
>> Christoph Hellwig <hch@infradead.org> wrote:
>> > Btw, what's the state of getting compatfd upstream?  It's a pretty
>> > annoying difference between qemu upstream and qemu-kvm.
>> 
>> I haven't tried.  I can try to send a patch.  Do you have any use case
>> that will help the cause?
>
> Well, the eventfd compat is used in the thread pool AIO code.  I don't
> know what difference it makes, but I really hate this code beeing
> different in both trees.  I want to see compatfd used either in both or
> none.

Discused with Anthony about it.  signalfd is complicated for qemu
upstream (too difficult to use properly), and eventfd ...  The current
eventfd emulation is worse than the pipe code that it substitutes.

His suggestion here was to create a new abstraction with an API like:

push_notify()

pop_notify()

and then you can implement it with eventfd() pipes/whatever.

What was missing for you of compatfd: qemu_eventfd/qemu_signalfd?
Do a push_notify()/pop_notify() work for you?

Later, Juan.