Re: [dpdk-dev] [PATCH v2 2/3] meson: use threads dependency as provided by meson

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

2021-03-23 13:35 (UTC+0000), Nick Connolly:
[...]
>  2. Adding -lpthread to libdpdk.pc is more problematic. The application
>     is almost
>     certain to be using a threads library. If this is a 3rd party
>     library, then the link
>     command will potentially include two libraries defining the same
>     exports.
>     Which one takes precedence will depend upon the ordering in the
>     application's
>     build system which seems somewhat arbitrary given that the DPDK
>     introduced
>     dependency is not required.

Agreed. In my tests it's "-pthread", not "-lpthread", but still.

See also comments here:
https://github.com/mesonbuild/meson/issues/553
Summary: dependency('threads') meaning is vague on Windows.

As a exotic case, I'm using NixOS which provides MinGW-w64 built with
mcfgthread (https://github.com/lhmouse/mcfgthread) and it doesn't even
recognize -pthread compiler flag, so this patch breaks cross-build for me.

> I'd still advocate for:
> 
> if not is_windows
>      threads_dep = dependency('threads')
> endif

It's more like, in lib/librte_telemetry/meson.build:

	if not is_windows
		ext_deps += threads_dep
	endif

Gabriel, by the way, why is it needed for librte_metrics?
Isn't librte_telemetry enough since it's a dependency to EAL?