Re: [FYI][PATCH 1/1] tools build: Remove needless libpython-version feature check that breaks test-all fast path

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: James Clark <james.clark@arm.com>
Cc: "Jaroslav Škarvada" <jskarvad@redhat.com>,
	"Adrian Hunter" <adrian.hunter@intel.com>,
	"Ian Rogers" <irogers@google.com>, "Jiri Olsa" <jolsa@kernel.org>,
	"Namhyung Kim" <namhyung@kernel.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	linux-perf-users@vger.kernel.org
Subject: Re: [FYI][PATCH 1/1] tools build: Remove needless libpython-version feature check that breaks test-all fast path
Date: Tue, 30 Nov 2021 11:33:01 -0300	[thread overview]
Message-ID: <YaY2HSVLmY9XZofB@kernel.org> (raw)
In-Reply-To: <4df4b76a-fbb5-89d8-fbef-fa844d8c1d3b@arm.com>

Em Tue, Nov 30, 2021 at 02:18:54PM +0000, James Clark escreveu:
> 
> 
> On 30/11/2021 13:26, Arnaldo Carvalho de Melo wrote:
> > Since 66dfdff03d196e51 ("perf tools: Add Python 3 support") we don't use
> > the tools/build/feature/test-libpython-version.c version in any Makefile
> > feature check:
> > 
> >   $ find tools/ -type f | xargs grep feature-libpython-version
> >   $
> > 
> > The only place where this was used was removed in 66dfdff03d196e51:
> > 
> >   -        ifneq ($(feature-libpython-version), 1)
> >   -          $(warning Python 3 is not yet supported; please set)
> >   -          $(warning PYTHON and/or PYTHON_CONFIG appropriately.)
> >   -          $(warning If you also have Python 2 installed, then)
> >   -          $(warning try something like:)
> >   -          $(warning $(and ,))
> >   -          $(warning $(and ,)  make PYTHON=python2)
> >   -          $(warning $(and ,))
> >   -          $(warning Otherwise, disable Python support entirely:)
> >   -          $(warning $(and ,))
> >   -          $(warning $(and ,)  make NO_LIBPYTHON=1)
> >   -          $(warning $(and ,))
> >   -          $(error   $(and ,))
> >   -        else
> >   -          LDFLAGS += $(PYTHON_EMBED_LDFLAGS)
> >   -          EXTLIBS += $(PYTHON_EMBED_LIBADD)
> >   -          LANG_BINDINGS += $(obj-perf)python/perf.so
> >   -          $(call detected,CONFIG_LIBPYTHON)
> >   -        endif
> > 
> > And nowadays we either build with PYTHON=python3 or just install the
> > python3 devel packages and perf will build against it.
> 
> I just tried this and found a combo that doesn't work and fails with this
> error (unrelated to this change): 
> 
>   Makefile.config:812: No 'python-config' tool was found: disables Python support - please install python-devel/python-dev
> 
> The combo is when the python2 runtime is installed, but the python3 devtools
> are installed. I didn't realise this when I added the python 3 autodetection,
> I only fixed the issue for a system that was solely python3.
> 
> Do you think I should fix this? Currently the workaround is PYTHON=python3,
> maybe it's enough of an edge case that it's ok?

We have a workaround, so perhaps you can just send a patch improving the
warning about python-config, suggesting to maybe using PYTHON=python3 on
the make command line?

But I won't complain if you want to provide something better :-)

> Reviewed-by: James Clark <james.clark@arm.com>

Thanks, adding it to the patch,

Regards,

- Arnaldo