linux-kernel - Re: [PATCH 28/28] perf tools: Add udis86 disassembler feature check

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Date:	Tue, 10 Dec 2013 16:31:51 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	linux-kernel@...r.kernel.org,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Namhyung Kim <namhyung@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Steven Rostedt <rostedt@...dmis.org>,
	David Ahern <dsahern@...il.com>
Subject: Re: [PATCH 28/28] perf tools: Add udis86 disassembler feature check


* Jiri Olsa <jolsa@...hat.com> wrote:

> On Thu, Dec 05, 2013 at 11:45:46AM +0100, Ingo Molnar wrote:
> 
> SNIP
> 
> > > > 
> > > > 1)
> > > > 
> > > > So, the first problem I can see is in the output:
> > > > 
> > > > Auto-detecting system features:
> > > > ...                     backtrace: [ on  ]
> > > > ...                         dwarf: [ on  ]
> > > > ...                fortify-source: [ on  ]
> > > > ...                         glibc: [ on  ]
> > > > ...                          gtk2: [ on  ]
> > > > ...                  gtk2-infobar: [ on  ]
> > > > ...                      libaudit: [ on  ]
> > > > ...                        libbfd: [ on  ]
> > > > ...                        libelf: [ on  ]
> > > > ...             libelf-getphdrnum: [ on  ]
> > > > ...                   libelf-mmap: [ on  ]
> > > > ...                       libnuma: [ on  ]
> > > > ...                       libperl: [ on  ]
> > > > ...                     libpython: [ on  ]
> > > > ...             libpython-version: [ on  ]
> > > > ...                      libslang: [ on  ]
> > > > ...                     libunwind: [ on  ]
> > > > ...                       on-exit: [ on  ]
> > > > ...            stackprotector-all: [ on  ]
> > > > ...                       timerfd: [ on  ]
> > > > 
> > > > config/Makefile:421: No udis86 support.
> > > > 
> > > > such a 'no XYZ support' message should only occur if a feature test 
> > > > failed. _If_ we decide that 'udis86' support is required for a full 
> > > > perf build then there should be a new line saying something like:
> > > > 
> > > > ...                        udis86: [ OFF ]
> > > 
> > > hum, just sent v4 that added udis86 into above list ;-)
> > > 
> > > So.. do we consider 'full perf build' to be build with all
> > > possible libraries linked in?
> > 
> > So my worry is, how widely is libudis86 available in distros? What is 
> > the package name on Debian/Ubuntu for example?
> 
> I did not find any.. :-\ I can see Fedora and Gentoo

That's a problem really - all perf developers who are using Ubuntu 
will see the failure, without being able to do anything about it.

So maybe we need an intermediate feature-mode for such convenience 
features that don't really impact measurement capabilities, those 
features could be probed but failures would not be displayed in such a 
highly prominent fashion.

Thanks,

	Ingo
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