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binutils 2.27 breaking Google coredumper...?


Hi all.  Does anyone have any experience with Google coredumper library?
 It used to be available at Google Code but mostly there are a bunch of
GitHub repos holding the code.  Mine is:
  https://github.com/madscientist/google-coredumper

We use this library to catch any sort of core, including both invoked
from inside our code (assert/abort/unhandled exception/SEGV/etc.) and
also from outside our code (SIGABRT).  It doesn't require any system or
user settings (e.g., ulimit, /proc, etc.) to be changed to work
properly, and it also writes already-compressed cores which is very
handy.

We've been using it for years on our GNU/Linux code (running on
x86_64/amd64) with GCC 4.9.2 and binutils 2.25 (built myself from
source).  Now I'm attempting to upgrade our toolchain to GCC 6.2.0 and
binutils 2.27.

Everything went fine (as far as compilation, running, etc.) except I
realized that when I try to read a core created with the coredumper
library (using GDB 7.11) it can't be read; the stack traces of all the
threads are corrupted.  I tried with both ld.gold and ld.bfd (but it may
not be a linker issue anyway).  Most look like this:

Thread 14 (LWP 9584):
#0  0x00007f1620ad5d84 in ?? ()
#1  0x0000000000000000 in ?? ()

Thread 13 (LWP 9585):
#0  0x00007f1620ad5d84 in ?? ()
#1  0x0000000000000000 in ?? ()

Thread 12 (LWP 9587):
#0  0x00007f1620ad5d84 in ?? ()
#1  0x0000000000000000 in ?? ()

Thread 11 (LWP 9589):
#0  0x00007f1620ad5d84 in ?? ()
#1  0x0000000000000000 in ?? ()

Thread 10 (LWP 9592):
#0  0x00007f1620ad5d84 in ?? ()
#1  0x0000000000000000 in ?? ()

etc.

I then tried to rebuild my toolchain with GCC 6.2.0 but staying with
binutils 2.25, and my coredumps worked again with this combo.

So, it appears something changed about the way binutils works between
2.25 and 2.27 that breaks Google coredumper.

I wonder if anyone here has any experience with this, or suggestions as
to where to look further or what types of things to experiment with.

I tried reading the various NEWS files in the binutils subdirectories
and the only one that jumped at me was compressed debug sections... but
maybe there are other things that could be involved?

Any suggestions, pointers, slaps upside the head, etc. would be greatly
appreciated...

Cheers!


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