Re: libbabeltrace feature detection message

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Mar 01, 2016 at 01:51:24PM +0100, Jiri Olsa escreveu:
> On Mon, Feb 29, 2016 at 12:07:20PM -0300, Arnaldo Carvalho de Melo wrote:
> > 
> > Hi Jiri,
> > 
> > 	While testing a patch by Wang, that requires building with
> > libbabeltrace, I noticed that there are no feature detection message
> > telling that it was found successfully. The end result is the desired
> > one, it builds with babeltrace, but I wonder if we couldn't have the
> > [ok] line for it:
> 
> well, we removed it, because the latest version if libbabeltrace pkg

And we should keep it like that, I'm talking about something else.

> perf needs wasn't present in common distros.. so for most users that
> would print 'OFF' as a status.. that might have changed now, dont know
> 
> anyway, for libbabeltrace and other in FEATURE_TESTS_EXTRA it's not possible
> to print their status easily at the moment, because the status isn't known at
> the time tools/build/Makefile.feature is included in config/Makefile

Ok, I guess this should then be the problem to solve, when possible,
i.e. what I am talking about is:

1. It should remain as is while the generally available babeltrace
   library doesn't have what we need.

2. But, if we explicitely ask for it to be built, then it should do the
   feature detection as usual, checking if what we asked it to do, to
   enable building with libbabeltrace, is possible, if so, print:

            babeltrace    [ok]

:-)
 
> I'll check if we can reorg the code a little to get the full status at the end

Thanks!
 
> jirka
> 
> > 
> > 
> > [acme@jouet linux]$ rm -rf /tmp/build/perf ; mkdir -p /tmp/build/perf ; make LIBBABELTRACE=1 O=/tmp/build/perf -C tools/perf install-bin
> > make: Entering directory '/home/acme/git/linux/tools/perf'
> >   BUILD:   Doing 'make -j4' parallel build
> > 
> > Auto-detecting system features:
> > ...                         dwarf: [ on  ]
> > ...                         glibc: [ on  ]
> > ...                          gtk2: [ on  ]
> > ...                      libaudit: [ on  ]
> > ...                        libbfd: [ on  ]
> > ...                        libelf: [ on  ]
> > ...                       libnuma: [ on  ]
> > ...        numa_num_possible_cpus: [ on  ]
> > ...                       libperl: [ on  ]
> > ...                     libpython: [ on  ]
> > ...                      libslang: [ on  ]
> > ...                     libcrypto: [ on  ]
> > ...                     libunwind: [ on  ]
> > ...            libdw-dwarf-unwind: [ on  ]
> > ...                          zlib: [ on  ]
> > ...                          lzma: [ on  ]
> > ...                     get_cpuid: [ on  ]
> > ...                           bpf: [ on  ]
> > 
> >   GEN      /tmp/build/perf/common-cmds.h
> >   CC       /tmp/build/perf/fixdep.o
> >   LD       /tmp/build/perf/fixdep-in.o
> > <SNIP>
> > [acme@jouet linux]$ ldd ~/bin/perf | grep babel
> > 	libbabeltrace-ctf.so.1 => /lib64/libbabeltrace-ctf.so.1 (0x00007fce5c405000)
> > 	libbabeltrace.so.1 => /lib64/libbabeltrace.so.1 (0x00007fce5bd69000)
> > [acme@jouet linux]$ 
> > 
> > 
> > - Arnaldo