Re: Problems with _Unwind_Backtrace() vs signal handlers

[Andrew Haley <aph at redhat dot com>]

Aaron W. LaFramboise writes:

 > I'm trying to learn about the situation with unwinding on GCC.  Is
 > there a general overview of the entire process availible somewhere?
 > How can I get up to speed so I know all about the _Unwind_
 > functions and how Dwarf2 exceptions work, etc?
 > 
 > In particular, what mechanism GCC use to get information directly from
 > glibc rather than MD_FALLBACK_FRAME_STATE_FOR?

gcc doesn't need to do anything if glibc makes dwarf2 info for an
exception frame.  As far as gcc is concerned, it's just another call
frame.

 > Who exactly is responsible for providing misc. unwind functions,
 > and where are they documented? 

It's in libgcc, which is in the same directory as gcc's C compiler.

 > I notice all of libgcc, glibc, and sometimes libunwind are
 > providing some sort of information, but I can't figure out who is
 > responsible for what.

libunwind is an alternative unwinder library.  The unwinder in libgcc
is a fairly minimalist implementation of what's needed.

Andrew.