linux-kernel - Re: [PATCH 2/2] perf annotate: add powerpc support

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Message-ID: <1465875647.31436.0.camel@ellerman.id.au>
Date:	Tue, 14 Jun 2016 13:40:47 +1000
From:	Michael Ellerman <mpe@...erman.id.au>
To:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	Anton Blanchard <anton@...abs.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	He Kuang <hekuang@...wei.com>
Subject: Re: [PATCH 2/2] perf annotate: add powerpc support

On Fri, 2016-06-10 at 20:08 +0530, Naveen N. Rao wrote:
> On 2016/06/10 10:36AM, Arnaldo Carvalho de Melo wrote:
> > Em Fri, Jun 10, 2016 at 06:32:51PM +0530, Naveen N. Rao escreveu:
> > > Convert ins__find() to a __weak function for generic functionality,
> > > while adding a powerpc-specific variant. We look at the function name
> > > for branch instructions and classify the instructions to one among a
> > > branch, a function call (branch with LR update) or a function return
> > > (branch to LR).
> > 
> > How would this allow one to get a perf.data collected on a powerpc
> > system, transfer it to a x86-64 (or aarch64, to mention another
> > workstation wannabe chip) system and then try annotating it?
> > 
> > There was a previous discussion about this, and it involved having all
> > yout ppc tables available as well as other arches tables, and then
> > choosing which one to use based on:
> > 
> > 	normalize_arch(thread->mg->machine->env->arch)
> > 
> > just like was done for support cross unwinding, see recent patch kit by
> > He Kuang, CCed.
> 
> Nice. This would be good to have. I will look at adding powerpc support 
> for cross-architecture unwind.
> 
> However, for cross-architecture annotation, I think there will be a lot 
> more dependencies since perf currently uses objdump to obtain the 
> disassembly. In addition, the actual binaries will also be needed.

It's possible to build a multi-arch objdump, I don't know if it's packaged on
all distros, or if perf wants to depend on it.

cheers