Hi Nityananda,
On Sat, Feb 7, 2009 at 1:52 AM, Nityananda <j.nityananda@gmail.com>
wrote:
HI Thiago,
Thanks for the information. I am reading the code to deal with the
stack
frame information without the debug information. Can you please
point me to
the code with the debug information? You mentioned that it uses
DWARF2.
Look at gdb/dwarf2-frame.c for DWARF2 frame reading .
So are the local variables always at the same offset of the frame
base address
or there is a possibility of these addresses changing from one
process to
another?
Local variables will always be at the same offset from the frame base
address for the same program unless you have self modifying code .
Operating Systems 101 - A process can be multiple instantiations of
the same program.
HTH
cheers
Ramana
Thank you very much in advance,
Nityananda
On Feb 6, 2009, at 4:01 AM, Thiago Jung Bauermann wrote:
Hi Nityananda,
El jue, 05-02-2009 a las 18:26 -0800, Nityananda escribió:
I am looking for how
GDB obtains the address of stack local variables. I am seeing some
code related to frame_info but do not know how it actually works.
Well, there are two situations: with debug information available,
and
without. For the first case it's simple: the DWARF2 format
includes the
frame base address as part of the unwind information, and
addresses of
local variables in the debuginfo are relative to that base address.
When there's no debuginfo available, GDB uses its knowledge of the
OS
ABI for the given architecture. For example, for ppc64-linux, the
stack
frame layout is given here:
http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#STACK
And the code which uses that knowledge is in
rs6000-tdep.c:rs6000_frame_cache. It's kinda hairy...
--
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center