Re: [PATCHv2 00/15] tools build: Move features framework into tools/build

[Arnaldo Carvalho de Melo <acme@redhat.com>]

Em Wed, Mar 18, 2015 at 07:59:16PM +0100, Jiri Olsa escreveu:
> On Wed, Mar 18, 2015 at 03:50:48PM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Mar 11, 2015 at 09:58:49AM +0100, Jiri Olsa escreveu:
> > >   git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
> > >   perf/build

> > Ok, so using the csets from the above branch, if I do:

> > [acme@ssdandy linux]$ rm -rf /tmp/build/perf ; mkdir -p /tmp/build/perf ; time make O=/tmp/build/perf -C tools/perf LIBBABELTRACE_DIR=/opt/libbabeltrace/ install-bin
> > make: Entering directory `/home/acme/git/linux/tools/perf'
> >   BUILD:   Doing 'make -j8' parallel build
> > config/Makefile:423: No libunwind found. Please install libunwind-dev[el] >= 1.1 and/or set LIBUNWIND_DIR

> > Auto-detecting system features:
> > ...                         dwarf: [ on  ]
> > ...                         glibc: [ on  ]
> > ...                          gtk2: [ on  ]
> > ...                      libaudit: [ on  ]
> > ...                        libbfd: [ on  ]
> > ...                        libelf: [ on  ]
> > ...                       libnuma: [ on  ]
> > ...                       libperl: [ on  ]
> > ...                     libpython: [ on  ]
> > ...                      libslang: [ on  ]
> > ...                     libunwind: [ OFF ]
> > ...            libdw-dwarf-unwind: [ on  ]
> > ...                          zlib: [ on  ]
> > ...     DWARF post unwind library: libdw

> > And then, despite not telling anything about babeltrace being linked,
> > i.e. the no line above with a [ on ], we get:

> libbabeltrace was taken out of the default display
> of features as requested, because the requested
> interface wasn't released yet

> you enabled it manually via LIBBABELTRACE_DIR='...',
> so it got linked.. but it wont appear in the default

I thought that what was requested was that it wouldn't be built, even if
the required libs were installed, i.e. by default it wouldn't be tried.

If I remove that LIBBABELTRACE_DIR all it will do is to try to build it
anyway and fail, which will make it emit the "support for CTF will not
be enabled since libbabeltrace-devel wasn't found, etc" like message,
which is confusing as well, because nobody will find, from a distro, a
libbabeltrace-devel that meeds this requirement, which I think is the
point Ingo tried to make, right?

My expectation, from what I've read in the discussion with Ingo, was
that NO_LIBBABELTRACE (sp?) would be turned on by default until we were
reasonably sure that the availability of the required functionality was
more or less widespread, i.e. that testing for it would have a high
degree of chances of succeeding, thus not slowing down the build process
most of the time for most of the users.

People wanting to build it would have to explicitely pass
NO_LIBBABELTRACE=0 or equivalent in the make command line.

Anyway, I applied the patch, as it is holding the other changes, we can
always fix this later.

- Arnaldo