Re: GDB bt command and core dumps

[Daniel Jacobowitz <drow@false.org>]

On Tue, Mar 24, 2009 at 07:58:18PM +0530, Amol Lad wrote:
> Hi,
> 
> I'm working on an ARM9 platform (running Linux 2.6.18) and using gdb
> 6.6 compiled for the platform. My application is a multithreaded
> application and on a crash it generates core of around 200MByte. I'm
> looking to reduce the size of the core file and I _only_ need gdb 'bt'
> command output ; no other debugging information (i.e I'm only
> interested in the call trace)
> 
> - I tried ulimit -c command but the core produced are not useful in most cases
> - I changed kernels fs/binfmt_elf.c file and modified maydump function
> to just add crashed thread's stack in the core but no success
> 
> What all information should be present in the core file so that bt
> output works reliably. Is stack of crashed thread not enough ? My
> application is compiled with -O2 (hence -fomit-frame-pointer)

You'll probably need the dynamic section, too - that's what GDB uses
to locate shared libraries.  I thought there was already a way to do
this, but I can't find it.  Stack and modified private copies of file
pages should approximate this, i.e. the data segment but not the heap.

-- 
Daniel Jacobowitz
CodeSourcery