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Date: Wed, 21 Mar 2018 16:38:07 +0100
From: Jiri Olsa <jolsa@redhat.com>
To: "Jin, Yao" <yao.jin@linux.intel.com>
Cc: acme@kernel.org, jolsa@kernel.org, peterz@infradead.org,
        mingo@redhat.com, alexander.shishkin@linux.intel.com,
        Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com,
        yao.jin@intel.com
Subject: Re: [PATCH] perf util: Display warning when perf report/annotate is
 missing some libs
Message-ID: <20180321153807.GA2707@krava>
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On Wed, Mar 21, 2018 at 10:11:10AM +0800, Jin, Yao wrote:
> Hi Jiri,
> 
> I'm still thinking it's worth displaying the warning when perf missing some
> libraries.
> 
> Somebody just told me that perf didn't work well. While after some
> investigations, I found it's just missing some libraries when building the
> perf.
> 
> But I have spent some time on getting the root cause. If with this patch, it
> should be very easily to know that.

true.. Arnaldo, any feedback on this one?

> > I just think it'd better provide some hints to user. For example,
> > "symbol is disabled and you need to install libelf/xxx", say something
> > like that.
> > 
> > But it looks the column can't contain too much information (i.e. no more
> > space to contain the entire hints).
> > 
> > Any idea? Or just add this warning in verbose mode?
> > 
> > > also your change does not affect tui mode
> > > 
> > > annotation for some reason does not start at all.. could be
> > > little more verbose ;-)
> > > 
> > > jirka
> > > 
> > 
> > Yes, it doesn't affect tui mode.
> > 
> > Or we just add this warning in verbose mode?
> > 
> > e.g. perf report -v?

how about displaying libraries separately with -vv output,
that would mimic the build message, like:

  $ ./perf -vv
  perf version 4.16.rc6.g18fd48

                   dwarf: [ on  ]
      dwarf_getlocations: [ 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  ]

and perf -vvv could display the 'make VF=1' info

jirka