Re: Can perf drop libunwind support

[Namhyung Kim <namhyung@kernel.org>]

Hi Ian,

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?
> 
> Possible savings:
>  - remove libunwind's 8 feature tests
>  - removal of 10 arch or not libunwind C files in perf
>  - removal of libunwind #ifdef-ed code throughout common files.

I'm ok with removing libunwind to reduce the maintenance burden.
In general, we'd better not have multiple libraries for the same
purpose.  Recently we added libllvm support, then it might replace
libelf, libdw and libcapstone someday. :)

Thanks,
Namhyung