[Dwarf-Discuss] question about variable locations from dwarf debugging information

Frank Ch. Eigler fche at redhat.com
Thu Jun 18 10:59:36 PDT 2009


Hi -

> I am working on a project which needs to get the variable location  
> from executable application. [...]

The first thing to understand is that this location can be a function
of program execution state (mainly PC value, but also register and
memory contents).  So the question only makes sense when specifying
the context.

> I am wondering: Is there any other tool which help me get the memory
> address of variables? Like "print variable_name" command in gdb,
> then I could get 0xff73d305. [...]

No doubt there are other tools, but the one closest to my chair
happens to be systemtap.  You could build it, then look at the output
of a little buddy diagnostic program "loc2c-test":

% nm a.out | grep main
000000000040ab00 T main
% ./loc2c-test -e a.out 0x000000000040ab00 argc
#define PROBEADDR 0x40ab00ULL
static void print_value(struct pt_regs *regs)
{
  intptr_t value;
  {
    { int32_t value = fetch_register (5);value = value; }
  }
  printk (" ---> %ld\n", (unsigned long) value);
  return;
}


- FChE



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