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

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Message-ID: <20160330150844.GD9083@tassilo.jf.intel.com>
Date:	Wed, 30 Mar 2016 08:08:44 -0700
From:	Andi Kleen <ak@...ux.intel.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org,
	Stephane Eranian <eranian@...gle.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andy Lutomirski <luto@...nel.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Zi Shen Lim <zlim.lnx@...il.com>
Subject: Re: [PATCH 10/11] perf tools: Add probing for udev86 library

> 
> Yeah, so udis86 also seems to be a pretty old, relatively stale library with no 
> support for new instructions AFAICS.

There are lots of new instructions in pull requests on github.

But yes the author seems to be a bit slow in pulling.

> 
> So I'd rather encourage librarizing one of the x86 instruction decoders in 
> arch/x86/, and adding pretty-printing functionality to it. The code can already 
> see instruction boundaries, which is the hardest part.
> 
> That would also be better supported on non-x86 architectures in the long run:
> 
>  triton:~/tip> find arch/ -name insn.c | xargs ls -l
>  -rw-rw-r-- 1 mingo mingo 30244 Mar 29 11:24 arch/arm64/kernel/insn.c
>  -rw-rw-r-- 1 mingo mingo  1347 Dec  8 06:27 arch/arm/kernel/insn.c
>  -rw-rw-r-- 1 mingo mingo 15123 Mar 30 12:31 arch/x86/lib/insn.c
> 
> Such an in-kernel-repo library could also be used by live kernel debuggers such as 
> kgdb/kdb, oops/crash-time disassembly printout, etc.
> 
> ... so how about that direction instead?

It's a major project. Who is gonna work on it? Are you volunteering?

Longer term I agree it would be reasonable (if someone can be found to work on it),
but short term udis86 is there and works today.

-Andi