Re: [PATCH] perf build: Add missing cflags when building with custom libtraceevent

[Leo Yan <leo.yan@arm.com>]

On Wed, Oct 30, 2024 at 10:45:47AM +0800, Yicong Yang wrote:

[...]

> >> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> >> index 4ddb27a48eed..53fc5f787a77 100644
> >> --- a/tools/perf/Makefile.config
> >> +++ b/tools/perf/Makefile.config
> >> @@ -1194,7 +1194,7 @@ endif
> >>  ifneq ($(NO_LIBTRACEEVENT),1)
> >>    $(call feature_check,libtraceevent)
> >>    ifeq ($(feature-libtraceevent), 1)
> >> -    CFLAGS += -DHAVE_LIBTRACEEVENT
> >> +    CFLAGS += -DHAVE_LIBTRACEEVENT $(shell $(PKG_CONFIG) --cflags libtraceevent)
> >
> > Does this solve the problem?  On my machine, it returns this:
> >
> >   $ pkg-config --cflags libtraceevent
> >   -I/usr/include/traceevent
> >
> >   $ ls /usr/include/traceevent/
> >   event-parse.h  event-utils.h  kbuffer.h  trace-seq.h
> >
> > So the include path should be "/usr/include" or we should include
> > <event-parse.h> directly.  We may update the every include statements
> > but just curious how it solved your problem.
> >
> 
> I think you're right, we should use the path according to the pkg-config outputs.
> But it's a different problem, for me it's due to the missing of the include path
> (my libtraceevent is not under the system path). With the fix you proposed and drop
> the change in my patch:
> 
> $ PKG_CONFIG_PATH=/home/yangyicong/Community/libtraceevent/install/usr/local/lib/aarch64-linux-gnu/pkgconfig/ pkg-config --cflags-only-I libtraceevent
> -I/home/yangyicong/Community/libtraceevent/install/usr/local/include/traceevent
> $ PKG_CONFIG_PATH=/home/yangyicong/Community/libtraceevent/install/usr/local/lib/aarch64-linux-gnu/pkgconfig/ make -C tools/perf NO_LIBPYTHON=1
> In file included from bench/../util/session.h:5,
>                  from bench/synthesize.c:12:
> bench/../util/trace-event.h:153:10: fatal error: event-parse.h: No such file or directory
>   153 | #include <event-parse.h>
>       |
> [...]
> 
> Checked how we handle with libtracefs currently:
>  ifeq ($(feature-libtracefs), 1)
>     CFLAGS +=  $(shell $(PKG_CONFIG) --cflags libtracefs) # we've added the cflags from pkg-config
>     LDFLAGS += $(shell $(PKG_CONFIG) --libs-only-L libtracefs)

The libtracefs.pc file claims requesting libtraceevent, as a result, it
returns the header paths for both libtraceevent and libtracefs:

  $ pkg-config --cflags libtracefs
  -I/usr/local/include/tracefs -I/usr/local/include/traceevent

I checked the packages libtraceevent-dev and libtracefs-dev and either
can be installed independently. Therefore, it seems to me that this
patch is correct for finding the traceevent header path, with no
dependency on tracefs.

Thanks,
Leo