Re: Problem with perf report --gtk

[Guilherme Amadio <amadio@gentoo.org>]

On Tue, Sep 09, 2025 at 06:04:42AM -0700, Ian Rogers wrote:
> On Tue, Sep 9, 2025 at 3:33 AM Guilherme Amadio <amadio@gentoo.org> wrote:
> >
> > Hi Arnaldo, Namhyung,
> >
> > Since sometime we have a bug in Gentoo's bugzilla about perf report --gtk not
> > working¹: https://bugs.gentoo.org/937869
> >
> > I know this feature is not used very much, but I thought I'd report in
> > any case. The problem is easily reproducible as shown below:
> >
> >
> > $ perf record -a -g -- sleep 1
> > [ perf record: Woken up 1 times to write data ]
> > [ perf record: Captured and wrote 1.818 MB perf.data (6648 samples) ]
> > $ LD_DEBUG=symbols perf report --gtk 2>&1 | grep '(fatal)'
> >     288067:     /usr/libexec/perf-core/libperf-gtk.so: error: symbol lookup error: undefined symbol: hashmap_find (fatal)
> > $ perf report --gtk
> > GTK browser requested but could not find libperf-gtk.so
> >
> > I tried this with perf 6.16, but this bug seems to have been there since
> > at least 6.12.
> >
> > Please let me know if it's better to file problems at https://bugzilla.kernel.org/.
> 
> Thanks for letting us know Guilherme! I suspect I broke things when
> trying to fix python things. The code linking libperf-gtk.so is:
> https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/Makefile.perf?h=perf-tools-next#n809
> The hashmap symbols are part of the perf-util library:
> https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/Build?h=perf-tools-next#n197
> So maybe there needs to be a libbpf -lbpf for your case? Alternatively
> we may need to reorder the libraries here:
> https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/Makefile.perf?h=perf-tools-next#n464
> like:
> PERFLIBS += $(LIBPERF_BENCH) $(LIBPERF_TEST) $(LIBPERF_UI) $(LIBPERF_UTIL)
> becomes:
> PERFLIBS += $(LIBPERF_BENCH) $(LIBPERF_TEST) $(LIBPERF_UTIL) $(LIBPERF_UI)

Thank you for the suggestion, but just changing the order of linking or
linking libbpf doesn't seem to fix the issue. I still see:

$ nm -D libperf-gtk.so | grep hashmap
                 U hashmap_find

at the end of the build. The function is in util/hashmap.c, so the
problem might be more involved than just the linking order.

Best regards,
-Guilherme