Re: [dpdk-dev] [PATCH v9 03/12] telemetry: initial telemetry infrastructure

[Thomas Monjalon <thomas@monjalon.net>]

27/10/2018 04:19, Van Haaren, Harry:
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > 27/10/2018 01:59, Harry van Haaren:
> > > --- a/mk/rte.vars.mk
> > > +++ b/mk/rte.vars.mk
> > > +JANSSON := $(shell pkg-config --exists jansson; echo $$?)
> > > +ifneq ($(JANSSON),0)
> > > +$(warning Jansson not found, disabling RTE_LIBRTE_TELEMETRY)
> > > +CONFIG_RTE_LIBRTE_TELEMETRY = n
> > > +endif
> > 
> > It fails for cross-compilation.
> > Example:
> > When compiling i686 on x86_64 host, no error with
> > 	pkg-config --exists jansson
> > but fails when linking:
> > 	/usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-pc-linux-
> > gnu/8.2.1/../../../libjansson.so when searching for -ljansson
> > 	/usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-pc-linux-
> > gnu/8.2.1/../../../libjansson.a when searching for -ljansson
> > 	/usr/bin/ld: skipping incompatible /usr/lib/libjansson.so when searching
> > for -ljansson
> > 	/usr/bin/ld: skipping incompatible /usr/lib/libjansson.a when searching
> > for -ljansson
> > 	/usr/bin/ld: cannot find -ljansson
> > 
> > Note: there is the same issue with examples/vm_power_manager/Makefile
> > 
> > I start thinking it is not reasonnable to enable an optional dependency
> > in our Makefiles. Perhaps the only solution is to use meson...
> 
> Ouch, yes if x86_64 pkg-config finds the available library, and it is not available in its i686 form, or other combinations thereof, things become another-level of complex.

On ArchLinux, I have pkg-config-32 for i686 libs.
And for true cross-compilation with sysroot, some environment variables
are required. See this doc:
	https://autotools.io/pkgconfig/cross-compiling.html

> Indeed Meson is (good | getting better) at detecting these things, Bruce knows more IIRC :)
> 
> @Thomas, for this release I propose to rework to use CONFIG=N as default for Make, and allow packagers to enable if they wish. Is that a good next-step?

Yes it looks reasonnable disabling telemetry by default in make case.