Solution sought to GCC 4.1.1 backtrace problem

[Blair Barnett]

Hi Andrew,

Thanks. So if I interpret your response correctly, even if I apply the patch to the 4.1.1 EABI gcc compiler code, I won't get the 3.3.2 non-EABI gcc result (i.e., I was able to unwind the backtrace across a signal handler frame using the 3.3.2 compiler)?

-blair

----- Original Message ----
From: Andrew Haley <aph-gcc@littlepinkcloud.COM>
To: Blair Barnett <blairbarnett@sbcglobal.net>
Cc: David Daney <ddaney@avtrex.com>; gcc-help mailing list <gcc-help@gcc.gnu.org>
Sent: Wednesday, August 29, 2007 11:59:18 AM
Subject: Re: Solution sought to GCC 4.1.1 backtrace problem

Blair Barnett writes:

 > We're using the EABI extensions, so I think we're safe there. We're
 > trying the patch now. However, being unfamiliar with this code, I'm
 > wondering how it works, since I don't see any calls to the new
 > functions in the patch:
 > http://gcc.gnu.org/ml/gcc-patches/2007-08/msg01388.html
 > 
 > Thanks for all the help! There may be light at the end of this tunnel!

For _Unwind_Backtrace to work, all code must be compiled with
-fexceptions.

Also, if you want to unwind through a signal handler you'll need some
code that recognizes a signal frame and unwinds through it.  There is
not yet any such thing for ARM EABI.  There's an example of how you do
this at x86_64_fallback_frame_state() in gcc/config/i386/linux-unwind.h.

This kind of thing is hard to write: I understand exactly how it all
works, and it would take me quite a while to figure out how to load
the _Unwind_Context from the sigcontext.

Andrew.