Re: [PATCH 1/3] perf tools: Separate lbfd check out of NO_DEMANGLE condition

[Jiri Olsa <jolsa@redhat.com>]

On Wed, Oct 02, 2013 at 10:18:32AM +0900, Namhyung Kim wrote:
> Hi Jiri,
> 
> On Sun, 29 Sep 2013 15:52:06 +0900, Namhyung Kim wrote:
> > Hi Jiri,
> >
> > 2013-09-27 (금), 16:32 +0200, Jiri Olsa:
> >> We fail build with NO_DEMANGLE with missing -lbfd externals error.
> >> The reason is that we now use bfd code in srcline object:
> >>   perf tools: Implement addr2line directly using libbfd
> >> 
> >> So we need to check/add -lbfd always now.
> >> 
> >> Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> >> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
> >> Cc: Ingo Molnar <mingo@elte.hu>
> >> Cc: Namhyung Kim <namhyung@kernel.org>
> >> Cc: Paul Mackerras <paulus@samba.org>
> >> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> >> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> >> Cc: David Ahern <dsahern@gmail.com>
> >> ---
> >>  tools/perf/config/Makefile | 17 ++++++++---------
> >>  1 file changed, 8 insertions(+), 9 deletions(-)
> >> 
> >> diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
> >> index 8b49a00..40a41c6 100644
> >> --- a/tools/perf/config/Makefile
> >> +++ b/tools/perf/config/Makefile
> >> @@ -360,6 +360,13 @@ else
> >>    endif
> >>  endif
> >>  
> >> +FLAGS_BFD=$(CFLAGS) $(LDFLAGS) $(EXTLIBS) -DPACKAGE='perf' -lbfd
> >> +has_bfd := $(call try-cc,$(SOURCE_BFD),$(FLAGS_BFD),libbfd)
> >> +ifeq ($(has_bfd),y)
> >> +  EXTLIBS += -lbfd
> >> +  CFLAGS += -DLIBBFD_SUPPORT
> >> +endif
> >> +
> >>  ifdef NO_DEMANGLE
> >>    CFLAGS += -DNO_DEMANGLE
> >>  else
> >> @@ -367,11 +374,7 @@ else
> >>      EXTLIBS += -liberty
> >>      CFLAGS += -DHAVE_CPLUS_DEMANGLE
> >>    else
> >> -    FLAGS_BFD=$(CFLAGS) $(LDFLAGS) $(EXTLIBS) -DPACKAGE='perf' -lbfd
> >> -    has_bfd := $(call try-cc,$(SOURCE_BFD),$(FLAGS_BFD),libbfd)
> >> -    ifeq ($(has_bfd),y)
> >> -      EXTLIBS += -lbfd
> >> -    else
> >> +    ifneq ($(has_bfd),y)
> >>        FLAGS_BFD_IBERTY=$(FLAGS_BFD) -liberty
> >>        has_bfd_iberty := $(call try-cc,$(SOURCE_BFD),$(FLAGS_BFD_IBERTY),liberty)
> >>        ifeq ($(has_bfd_iberty),y)
> >> @@ -397,10 +400,6 @@ else
> >>    endif
> >>  endif
> >>  
> >> -ifndef ($(filter -lbfd,$(EXTLIBS)),)
> >> -  CFLAGS += -DLIBBFD_SUPPORT
> >> -endif
> >> -
> >>  ifndef NO_STRLCPY
> >>    ifeq ($(call try-cc,$(SOURCE_STRLCPY),,-DHAVE_STRLCPY),y)
> >>      CFLAGS += -DHAVE_STRLCPY
> >
> > Is it enough to check on -lbfd only?  I guess libbfd can have additional
> > dependencies to libiberty and libz.  If so, this patch can fail to set
> > -DLIBBFD_SUPPORT, right?
> 
> I tested this on my system.  At first I guessed (without testing) it
> cannot build SOURCE_BFD with -lbfd only due to additional -liberty and
> -lz dependency, but it's not.  Actually the libfd.so is a plain text
> file which contains linker script like this:
> 
>   $ file /lib64/libbfd.so
>   /lib64/libbfd.so: ASCII text
> 
>   $ cat /lib64/libbfd.so
>   /* GNU ld script */
>   
>   /* Ensure this .so library will not be used by a link for a different format
>      on a multi-architecture system.  */
>   OUTPUT_FORMAT(elf64-x86-64)
>   
>   /* The libz dependency is unexpected by legacy build scripts.  */
>   INPUT ( /usr/lib64/libbfd.a -liberty -lz )
> 
> 
> So it should handle external dependencies.  But it doesn't.
> 
>   $ cat bfd.c
>   #include <bfd.h>
>   
>   int main(void)
>   {
>   	bfd_demangle(0, 0, 0);
>   	return 0;
>   }
> 
>   namhyung@sejong:tmp$ gcc bfd.c -lbfd
>   /usr/lib64/libbfd.a(plugin.o): In function `try_load_plugin':
>   (.text+0x1ab): undefined reference to `dlopen'
>   /usr/lib64/libbfd.a(plugin.o): In function `try_load_plugin':
>   (.text+0x1ca): undefined reference to `dlsym'
>   /usr/lib64/libbfd.a(plugin.o): In function `try_load_plugin':
>   (.text+0x263): undefined reference to `dlerror'
>   collect2: error: ld returned 1 exit status
> 
> 
> It seems that it needs libdl for loading plugins.  Adding -ldl makes
> above build successfully.  So we need to add -ldl for EXTLIBS IMHO.
> Without it, make NO_GTK2=1 NO_LIBPERL=1 NO_LIBPYTHON=1 will fail to
> check libbfd correctly (FYI, libperl and libpython add -ldl to the
> dependency list).

hum, so on my system -liberty check wins without -lbfd,
so 'NO_GTK2=1 NO_LIBPERL=1 NO_LIBPYTHON=1' passes

I need to check Ingo's latest changes on this, not sure how
if this problem is relevant any longer ;-)

jirka