Re: Can perf drop libunwind support

[Frederic Weisbecker <frederic@kernel.org>]

Le Mon, Oct 28, 2024 at 01:03:03PM -0300, Arnaldo Carvalho de Melo a écrit :
> On Wed, Oct 23, 2024 at 02:57:05PM -0700, Ian Rogers wrote:
> > Hi,
> > 
> > perf wants to build with BPF support these days. libbpf has a
> > dependency on libelf, part of elfutils. libdw is also part of elfutils
> > and amongst other things provides unwinding support. My understanding
> > is libdw unwinding is used by perf in preference to libunwind when
> > present. My suspicion is that libunwind is being feature tested,
> > linked against but then seldom or never used. Given this could perf
> > drop libunwind support in order to simplify the code base?
> 
> Probably Jiri remembers the reasons for us to have support for both,
> IIRC libunwind was a bit more mature at the time and so we decided to
> have both and when some broken behaviour appears we try the other one,
> in the process trying to fix the one wioth a problem?
> 
> Adding Frederic as well, this is when we started to use libunwind:

Ouch, memories are blurry... It's possible that libdw deprecated
libunwind at some point. I'm sorry I completely lost track of these
things since then :-s

thanks.