Re: Solution sought to GCC 4.1.1 backtrace problem

[Andrew Haley <aph-gcc at littlepinkcloud dot COM>]

Blair Barnett writes:

 > 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)?

That would be my guess.  But, to be honest, I have absolutely no idea
how 3.3.2 non-EABI backtraces() managed to unwind through a sighandler
frame.  If I were you I'd go with my first suggestion: it's easy to
try.

Andrew.

 > ----- 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.
 > 
 > 
 > 
 >