Re: Two questions on perf dwarf callchains

[Mauro Andreolini <mauro.andreolini@gmail.com>]

Il giorno ven, 17/01/2014 alle 12.11 -0800, Andi Kleen ha scritto:
> Mauro Andreolini <mauro.andreolini@gmail.com> writes:
> > file to get perf report to print the function names.
> > Is this expected behaviour? How do I get perf to automatically extract
> > symbols from compressed files?
> 
> Someone would need to write the code to do that I guess.
OK.

> >
> > To which function would 0x7facc1df12a0 match? It does not even seem to
> > be in the mapped address space of "ls". I am clueless.
> 
> The unwinder got confused. A common cause is incomplete or partially
> broken dwarf unwind information. May be a compiler problem.
Thanks for your time. Right now I am using gcc 4.8.2 20131219
(prerelease) and libunwind 1.1. I noticed the following
compile flags: "-O2 -g -fvar-tracking-assignments". I thought that
maybe optimizations like function inlining and the like would not play
together with debugging info, so I changed them to "-Og -g3
-fvar-tracking-assignments" and recompiled anything, albeit with no
luck. I must be missing something big here. How can I be sure to give
correct dwarf unwind information?

Mauro