On Monday 01 December 2014 01:06:12 Lennart Poettering wrote: > On Mon, 24.11.14 20:00, Peter Wu (pe...@lekensteyn.nl) wrote: > > > The --gc-sections linker option triggers a bug in the gold linker[1] which > > results in a bogus .eh_frame section making debugging harder: gdb backtraces > > stop at a library built by systemd and libunwind simply segfaults. > > To my knowledge libunwind is mostly obsolete, and libelfutils should > be used instead.
The Fedora maintainer dropped libunwind support, but there is still upstream activity. Documentation of libunwind is superior to libelfutils. Even by looking in the headers, I could not find a way to get a backtrace in libelfutils. libunwind backtracing functionality is signal and thread-safe while libelfutils does not have a strong focus on that as far as I can see. See also the discussion on this X patch where libelfutils was ultimately dropped in favor if libunwind. https://freedesktop.org/patch/15054/ > > Workaround by that bug by removing the option. The additional disk space > > saved by this option is marginal anyway (less than 1%). To illustrate this, > > see > > this `du -ks` on the installed files: > > > > 83548 without-gc-sections/install > > 25796 without-gc-sections/install-strip > > 83432 with-gc-sections/install > > 25752 with-gc-sections/install-strip > > > > [1]: https://sourceware.org/bugzilla/show_bug.cgi?id=17639 > > Are you sure you built the non-debug build? Just ./autogen.sh && ./configure, nothing fancy. The default options include '-g', but for some reason the linking drops this option and there are no debugging symbols. > The reason we use gc-sections logic is that much of what we hae in > src/shared/ is linked into every single binary we have even though > most binaries need only very little of it. We rely on the linker to > remove all the bits that are unnecessary hence. It turns out that my compiler (GCC 4.9.2) behaved worse with --gc-sections because LTO already optimized the unused parts away. -- Kind regards, Peter https://lekensteyn.nl _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel