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Re: [PATCH 10/11] perf tools: Add probing for udev86 library

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On Wed, Mar 30, 2016 at 12:43:27PM +0200, Ingo Molnar wrote:
> 
> * Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> 
> > From: Andi Kleen <ak@linux.intel.com>
> > 
> > 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

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[GIT PULL 00/11] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 09/11] perf tools: Add support for skipping itrace instructions Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 08/11] perf script perl: Perl scripts now get a backtrace, like the python ones Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 01/11] perf mem: Add -U/-K (--all-user/--all-kernel) options Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 05/11] perf config: Remove duplicated set_buildid_dir calls Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 11/11] perf script: Add support for printing assembler Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 02/11] perf tools: Make hists__collapse_insert_entry static Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 07/11] perf config: Rename 'v' to 'home' in set_buildid_dir() Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 03/11] perf tools: Make -f/--force option documentation consistent across tools Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 10/11] perf tools: Add probing for udev86 library Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
    Re: [PATCH 10/11] perf tools: Add probing for udev86 library Ingo Molnar <mingo@kernel.org> - 2016-03-30 12:50 +0200
      Re: [PATCH 10/11] perf tools: Add probing for udev86 library Arnaldo Carvalho de Melo <acme@redhat.com> - 2016-03-30 15:40 +0200
        Re: [PATCH 10/11] perf tools: Add probing for udev86 library Ingo Molnar <mingo@kernel.org> - 2016-03-30 16:00 +0200
          Re: [PATCH 10/11] perf tools: Add probing for udev86 library Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 16:20 +0200
            Re: [PATCH 10/11] perf tools: Add probing for udev86 library Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 16:50 +0200
              Re: [PATCH 10/11] perf tools: Add probing for udev86 library Ingo Molnar <mingo@kernel.org> - 2016-03-31 08:40 +0200
          Re: [PATCH 10/11] perf tools: Add probing for udev86 library Andi Kleen <ak@linux.intel.com> - 2016-03-30 17:10 +0200
            Re: [PATCH 10/11] perf tools: Add probing for udev86 library Ingo Molnar <mingo@kernel.org> - 2016-03-31 09:00 +0200
      Re: [PATCH 10/11] perf tools: Add probing for udev86 library Andi Kleen <ak@linux.intel.com> - 2016-03-30 16:50 +0200
  [PATCH 06/11] perf config: Rework buildid_dir_command_config to perf_buildid_config Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200
  [PATCH 04/11] perf tests: Add test to check for event times Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-03-30 01:50 +0200

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