From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754560AbcC3OmX (ORCPT ); Wed, 30 Mar 2016 10:42:23 -0400 Received: from mga04.intel.com ([192.55.52.120]:13209 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752107AbcC3OmV (ORCPT ); Wed, 30 Mar 2016 10:42:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,416,1455004800"; d="scan'208";a="678021542" Date: Wed, 30 Mar 2016 07:42:19 -0700 From: Andi Kleen To: Ingo Molnar Cc: Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Stephane Eranian , Arnaldo Carvalho de Melo Subject: Re: [PATCH 10/11] perf tools: Add probing for udev86 library Message-ID: <20160330144219.GC9083@tassilo.jf.intel.com> References: <1459294889-12148-1-git-send-email-acme@kernel.org> <1459294889-12148-11-git-send-email-acme@kernel.org> <20160330104326.GB4681@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160330104326.GB4681@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 30, 2016 at 12:43:27PM +0200, Ingo Molnar wrote: > > * Arnaldo Carvalho de Melo wrote: > > > From: Andi Kleen > > > > Add autoprobing for the udev86 disassembler library. > > So the typo in the title is confusing, what is 'udev86'? Agreed, it's confusing. It was meant to be udis86. http://udis86.sourceforge.net The next patch that uses it had the URL too, but that didn't make it when this patch was split off. > > Also, this library does not seem to be available on stock Ubuntu. We should not be > adding library dependencies that cannot be resolved on major distros: > > ... get_cpuid: [ on ] > ... bpf: [ on ] > ... udis86: [ OFF ] It's a chicken'n'egg problem. Likely when perf needs it they will add it soon. For now it's fairly easy to install manually. Using a real disassembler in perf has a lot of advantages over objdump. It allows full instruction traces with PT, which is useful for debugging. It also allows hot path analysis of branch mispredictions and automatic micro benchmarks using LBRs (implemented inn https://lkml.org/lkml/2016/3/28/331). Possibly more in the future. -Andi