Re: [perf top] annotation doesn't work, libunwind doesn't seem to be working either

[Ingo Molnar <mingo@kernel.org>]

* Namhyung Kim <namhyung@kernel.org> wrote:

> >  /usr/bin/ld: test-libunwind.c:(.text+0x44): undefined reference to `_Ux86_64_init_remote'
> >  /usr/bin/ld: test-libunwind.c:(.text+0x6b): undefined reference to `_Ux86_64_dwarf_search_unwind_table'
> >  collect2: error: ld returned 1 exit status
> > 
> > I tried to install the libunwind-19-dev package, I tried to 
> > uninstall/reinstall - no combination seems to work.
> > 
> > perf is also totally unhelpful about resolving such issues - it used to 
> > issue tips about what packages to install, but those tips are not 
> > present anymore, for this one at least.
> 
> Since v6.13, we switched to disable libunwind by default and used 
> unwinding in libdw.
> 
> commit 13e17c9ff491 ("perf build: Make libunwind opt-in rather than 
> opt-out")
> 
> You need to pass LIBUNWIND=1 to build with it.

So, users (including me) have absolutely no idea which unwinding 
library they want to build with: 99% of them would like to have a 
clean, full-featured perf build with all libraries marked as '[ on ]' 
in the build log. :-)

> > Within 'perf top' I go into a function, and I press 's', which is 
> > supposed to toggle the source code annotation ... but nothing happens.
> > 
> > 'nothing happens' is perhaps the most passive-aggressive reaction a 
> > tool can give to a user. I'd prefer a *crash* to ignoring the keypress 
> > ...
> 
> Oh ok.  I prefer a warning. :)

There's a zillion other things I'd prefer over the current behavior, 
what I wanted to say was that *even a crash* is superior to a puzzling 
'nothing' :-)

Thanks,

	Ingo