Re: [PATCH 1/1 next] tools build: Remove the libunwind feature tests from the ones detected when test-all.o builds

[Jiri Olsa <olsajiri@gmail.com>]

On Tue, Mar 18, 2025 at 04:51:53PM -0700, Namhyung Kim wrote:
> Hello,
> 
> On Mon, Mar 17, 2025 at 09:19:22PM +0000, Quentin Monnet wrote:
> > 2025-03-17 10:16 UTC-0700 ~ Ian Rogers <irogers@google.com>
> > > On Mon, Mar 17, 2025 at 10:06 AM Namhyung Kim <namhyung@kernel.org> wrote:
> > >>
> > >> Hello,
> > >>
> > >> On Mon, Mar 17, 2025 at 09:10:29AM -0700, Ian Rogers wrote:
> > >>> On Wed, Dec 11, 2024 at 7:45 AM Arnaldo Carvalho de Melo
> > >>> <acme@kernel.org> wrote:
> > >>>>
> > >>>> We have a tools/build/feature/test-all.c that has the most common set of
> > >>>> features that perf uses and are expected to have its development files
> > >>>> available when building perf.
> > >>>>
> > >>>> When we made libwunwind opt-in we forgot to remove them from the list of
> > >>>> features that are assumed to be available when test-all.c builds, remove
> > >>>> them.
> > >>>>
> > >>>> Before this patch:
> > >>>>
> > >>>>   $ rm -rf /tmp/b ; mkdir /tmp/b ; make -C tools/perf O=/tmp/b feature-dump ; grep feature-libunwind-aarch64= /tmp/b/FEATURE-DUMP
> > >>>>   feature-libunwind-aarch64=1
> > >>>>   $
> > >>>>
> > >>>> Even tho this not being test built and those header files being
> > >>>> available:
> > >>>>
> > >>>>   $ head -5 tools/build/feature/test-libunwind-aarch64.c
> > >>>>   // SPDX-License-Identifier: GPL-2.0
> > >>>>   #include <libunwind-aarch64.h>
> > >>>>   #include <stdlib.h>
> > >>>>
> > >>>>   extern int UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
> > >>>>   $
> > >>>>
> > >>>> After this patch:
> > >>>>
> > >>>>   $ grep feature-libunwind- /tmp/b/FEATURE-DUMP
> > >>>>   $
> > >>>>
> > >>>> Now an audit on what is being enabled when test-all.c builds will be
> > >>>> performed.
> > >>>>
> > >>>> Fixes: 176c9d1e6a06f2fa ("tools features: Don't check for libunwind devel files by default")
> > >>>> Cc: Adrian Hunter <adrian.hunter@intel.com>
> > >>>> Cc: Ian Rogers <irogers@google.com>
> > >>>> Cc: James Clark <james.clark@linaro.org>
> > >>>> Cc: Jiri Olsa <jolsa@kernel.org>
> > >>>> Cc: Kan Liang <kan.liang@linux.intel.com>
> > >>>> Cc: Namhyung Kim <namhyung@kernel.org>
> > >>>> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > >>>
> > >>> Sorry for the delay on this.
> > >>>
> > >>> Reviewed-by: Ian Rogers <irogers@google.com>
> > >>
> > >> Thanks for the review, but I think this part is used by other tools like
> > >> BPF and tracing.  It'd be nice to get reviews from them.
> > > 
> > > Sgtm. The patch hasn't had attention for 3 months. A quick grep for
> > > "unwind" and "UNW_" shows only use in perf and the feature tests.
> > > 
> > > Thanks,
> > > Ian
> > 
> > 
> > Indeed, bpftool does not rely on libunwind, and I don't remember other
> > BPF components doing so, either.
> 
> Right, but my concern was about the feature test itself and the related
> changes in the build files.
> 
> Can I get your Acked-by then?

hi,
I might be missing something, but I see following commit in git already:
  b40fbeb0b1cd tools build: Remove the libunwind feature tests from the ones detected when test-all.o builds

jirka