Comment 14 for bug 1567219

(In reply to Роман Донченко from comment #11)
> (In reply to Mark Wielaard from comment #10)
> > Debian does not seems to use GNU .zdebug compression,
>
> It does, though not for all packages yet. Here's an example:
> <https://packages.debian.org/jessie/debug/libopenjpeg5-dbg>.

O, indeed that one does use GNU .zdebug compression. But others like https://packages.debian.org/stretch/libc6-dbg seem to use a different ELF section compression method (use normal .debug names and set the SHF_COMPRESSED flag to indicate that the section data contains a ELF_Chdr plus compressed data).

Now I am slightly confused, what is Debian really using and why?

> > On x86_64 you can at least get call stacks, since .eh_frame is mandatory,
> > > but on, say, ARM or ARM64 it's not. So the call stacks stop at the first
> > > C-only library.
> >
> > That is a different Debian bug though, gcc: Enable
> > -fasynchronous-unwind-tables on more arches:
> > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=746426
>
> I wouldn't really call that a bug. Yeah, they don't build with that flag,
> but they don't have to. Debugging symbols provide the same information.

Except that most people won't have the debug files installed, not all packages have them and if they use GNU .zdebug or ELF section compression then, as this bug points out, valgrind won't be able to use them :) Other distros do use -fasynchronous-unwind-tables on all arches to make sure the unwind tables are always there, which does make lots of tools (not just valgrind) happy.