Re: [PATCH v2 1/2] tools lib traceevent: Export dynamic symbols used by traceevent plugins

[He Kuang]

Hi, jirka

On 2015/5/13 22:50, Jiri Olsa wrote:
> On Tue, May 12, 2015 at 11:25:45PM +0800, hekuang wrote:
> > Hi, jirka
> >
> > On 05/12/2015 08:37 PM, Jiri Olsa wrote:
> > > On Tue, May 12, 2015 at 06:41:56AM +0000, He Kuang wrote:
> > >
> > > SNIP
> > >
> > > >   	$(Q)$(MAKE) $(build)=perf
> > > > -$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN)
> > > > -	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(PERF_IN) $(LIBS) -o $@
> > > > +LD_LIBTRACEEVENT_FLAGS += -Xlinker --dynamic-list=$(LIBTRACEEVENT_DYNAMIC_LIST)
> > > > +$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN) $(LIBTRACEEVENT_DYNAMIC_LIST)
> > > > +	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(LD_LIBTRACEEVENT_FLAGS) $(PERF_IN) $(LIBS) -o $@
> > > >   $(GTK_IN): FORCE
> > > >   	$(Q)$(MAKE) $(build)=gtk
> > > > @@ -373,7 +375,13 @@ $(LIB_FILE): $(LIBPERF_IN)
> > > >   LIBTRACEEVENT_FLAGS += plugin_dir=$(plugindir_SQ)
> > > >   $(LIBTRACEEVENT): FORCE
> > > > -	$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) $(OUTPUT)libtraceevent.a plugins
> > > > +	$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) $(OUTPUT)libtraceevent.a
> > > > +
> > > > +libtraceevent_plugins: FORCE
> > > > +	$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) plugins
> > > > +
> > > > +$(LIBTRACEEVENT_DYNAMIC_LIST): libtraceevent_plugins
> > > > +	$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) $(OUTPUT)libtraceevent-dynamic-list
> > > I thought the idea of v2 was not to introduce new target,
> > > something like in attached patch (not completely tested)
> > >
> > > jirka
> >
> > There is a problem, the target perf executable is dependent on
> > the dynamic-list-file, so we should add plugins or the
> > dynamic-list-file to perf's dependencies.
> >
> > As your patch below, the dynamic-list-file is built implictly
> > when building plugins, so we should not add it directly to the
> > dependency list of perf.
> >
> > It seems new targets are needed. In the v2 patch,
>
> hum, I dont get it.. why ?
>
> dynamic-list-file gets rebuilt any time plugins are rebuilt..
> why not keep just the 'plugins' dependency?

You can test your patch as following steps:

$ touch ../lib/traceevent/plugin_function.c
$ make
  CC       plugin_function.o
  LD       plugin_function-in.o
  LINK     plugin_function.so
  GEN      libtraceevent-dynamic-list

perf is not rebuilt. There should be a 'GEN perf', right?

> jirka

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