[PATCH v3 7/8] perf python: Switch module to linking libraries from building source

[Ian Rogers]

On Tue, Jun 25, 2024 at 10:48 AM Namhyung Kim <namhyung at kernel.org> wrote:
>
> Hello,
>
> On Tue, Jun 25, 2024 at 5:24 AM James Clark <james.clark at arm.com> wrote:
> >
> >
> >
> > On 24/06/2024 23:26, Namhyung Kim wrote:
> > > On Thu, Jun 13, 2024 at 04:31:21PM -0700, Ian Rogers wrote:
> > >> setup.py was building most perf sources causing setup.py to mimic the
> > >> Makefile logic as well as flex/bison code to be stubbed out, due to
> > >> complexity building. By using libraries fewer functions are stubbed
> > >> out, the build is faster and the Makefile logic is reused which should
> > >> simplify updating. The libraries are passed through LDFLAGS to avoid
> > >> complexity in python.
> > >>
> > >> Force the -fPIC flag for libbpf.a to ensure it is suitable for linking
> > >> into the perf python module.
> > >>
> > >> Signed-off-by: Ian Rogers <irogers at google.com>
> > >> Reviewed-by: James Clark <james.clark at arm.com>
> > >> ---
> > >>  tools/perf/Makefile.config |   5 +
> > >>  tools/perf/Makefile.perf   |   6 +-
> > >>  tools/perf/util/python.c   | 271 ++++++++++++++-----------------------
> > >>  tools/perf/util/setup.py   |  33 +----
> > >>  4 files changed, 110 insertions(+), 205 deletions(-)
> > >>
> > >> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > >> index 7f1e016a9253..639be696f597 100644
> > >> --- a/tools/perf/Makefile.config
> > >> +++ b/tools/perf/Makefile.config
> > >> @@ -910,6 +910,11 @@ else
> > >>           endif
> > >>           CFLAGS += -DHAVE_LIBPYTHON_SUPPORT
> > >>           $(call detected,CONFIG_LIBPYTHON)
> > >> +     ifeq ($(filter -fPIC,$(CFLAGS)),)
> > >
> > > Nitpick: mixed TAB and SPACEs.

Will fix it in v2.

> > >
> > >
> > >> +           # Building a shared library requires position independent code.
> > >> +           CFLAGS += -fPIC
> > >> +           CXXFLAGS += -fPIC
> > >> +         endif
> > >
> > >
> > > I'm curious if it's ok for static libraries too..
> > >
> > > Thanks,
> > > Namhyung
> > >
> >
> > I think I tested the whole set with a static build so it should be ok.
>
> Ok, thanks for checking that!

Even with a static build it is often the case that the executable is
position independent (-fPIE, and related compiler options) and so
would need this too.

Thanks,
Ian

> Namhyung