lib: posix: allow eventfd on ARCH_POSIX platform

[TomzBench]

Is your enhancement proposal related to a problem? Please describe.
I would like to be able to use eventfd on native_posix_64 platform for testing purposes.

Describe the solution you'd like
Currently - eventfd is treated as a general library feature and maintained under lib/posix ... And this feature depends on !ARCH_POSIX. However - other socket API do not have this same limitation. ...In the context of zephyr, I think eventfd is more of a network feature as this API is only useful when using zsock_poll (as opposed to the more universal k_poll).

So my proposal is to name space this feature using the same infrastructure as other socket API methods. zsock_eventfd. The feature could be an addon similar to socketpair.

Describe alternatives you've considered
I could use zsock_socketpair - however, this is a more heavy weight solution for my use case, and adds addition prj.conf with extra requirements that should not be necessary for my use case (aka: HEAP_MEM_POOL_SIZE, SOCKETPAIR_BUFFER_SIZE)

Additional context
For history - here is the PR where it was decided to require !ARCH_POSIX, #22863
I hope this can be re-evaluated.

[aescolar]

With the new native_sim (successor of native_posix) eventfd can be used.
Therefore closing as done.

[TomzBench]

great !

[TomzBench]

@aescolar

does native_sim/native/64 support eventfd with zsock_poll? This feature works on my hardware archtecture but fails for me in native_sim. the file descriptor is a ZSOCK_POLLNVAL (bad file descriptor) when polling an eventfd file descriptor. The eventfd_read|write calls work but I cannot get polling to work so far

[aescolar]

does native_sim/native/64 support eventfd with zsock_poll?

@TomzBench It should , but maybe the default C library is not defaulting to PICO if you only enable it, so you have host glibc headers in the way breaking things. Can you create a separate bug report?

[TomzBench]

@aescolar

Yes it's my mistake. It pulled in the host eventfd some how. Everything working as intended now.

Thanks!