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@xxxxxxxxxxxxxxxxxxx> To: Blair Barnett <blairbarnett@xxxxxxxxxxxxx> Cc: David Daney <ddaney@xxxxxxxxxx>; gcc-help mailing list <gcc-help@xxxxxxxxxxx> 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.
