linux-kernel - Re: [RFC 0/5] perf tools: Minimalistic build without libelf dependency

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Date:	Mon, 14 May 2012 11:22:07 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Namhyung Kim <namhyung.kim@....com>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC 0/5] perf tools: Minimalistic build without libelf
 dependency


* Namhyung Kim <namhyung.kim@....com> wrote:

> Hi,
> 
> NOTE: This is a RFC patchset and it contains a lot of rough edges
> and ugly codes.
> 
> Current build procedure of perf tools requires a couple of external
> libraries. Although most of them are optional, elfutils' libelf is
> mandatory for resolving symbols and build-id of the binaries being
> profiled. For some reason, it makes embedded guys' life harder who
> want to build and run perf tools on their boards.

Yeah, and this is a very useful patchset from that perspective.

> This patch set tries to fix the problem by letting the perf could
> be built without libelf. The initial intent was just providing
> perf record command to gather performance events interested on the
> system and copies the data to development box to be used by perf
> report for analysis.
> 
> However it's changed to have most of perf commands as is because
> perf can resolve kernel symbols without libelf and many of perf
> commands deal (mostly) with kernel events - so no need to restrict
> capability of perf tools. Therefore, the end result is not so
> minimalistic in fact and only thing it cannot do is "perf probe".
>
> And then I realized that the perf record needs to know about the
> build-id's anyway :(. So I implemented a poor man's version of elf
> parser only for parsing the build-id info.
> 
> To build a minimal perf tools, pass MINIMAL=1 to make. The perf
> report will not display symbol names:

Could we make this automatic when the required elf libraries are 
not present?

Thanks,

	Ingo
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