> > >
> > > I can't say I know why it's needed, but the change seems consistent with
> > > other Eventdev trace points.
> >
> > The trace point framework in DPDK relies on a per trace point global
> > variable (whose name is __<trace point name>):
> >
> > #define __RTE_TRACE_POINT(_mode, _tp, _args, ...) \
> > extern rte_trace_point_t __##_tp; \
> > static __rte_always_inline void \
> > _tp _args \
> > { \
> > __rte_trace_point_emit_header_##_mode(&__##_tp); \
> > __VA_ARGS__ \
> > }
> >
> > When tracepoints are called from within a shared library code, and
> > because all symbols of a group of objects are visible, the tracepoint
> > symbols are resolved by the linker.
> > But when this tracepoint is called via an inline helper from some code
> > out of the shared library, this symbol must be exported in the shared
> > library map or it won't be visible to "external" users.
>
> Could we describe / mention this in the trace point library doc?
> Or maybe I read too quickly and there is already something but it was
> not obvious to me.
Following text is available in
https://doc.dpdk.org/guides/prog_guide/trace_lib.html as NOTE.
We may need to update to very specific on FP trace points.
The RTE_TRACE_POINT_REGISTER defines the placeholder for the
rte_trace_point_t tracepoint object. For generic tracepoint or for
tracepoint used in public header files, the user must export a
__<trace_function_name> symbol in the library .map file for this
tracepoint to be used out of the library, in shared builds. For
example, __app_trace_string will be the exported symbol in the above
example.
>
>
> --
> David Marchand
>
