Re: [Qemu-devel] Trouble with GDB & Some 'Can it be done' Debugging questions

[Daniel Jacobowitz <drow@false.org>]

On Wed, Jul 19, 2006 at 08:43:57AM +0000, Steve Ellenoff wrote:
> #3) Anytime I try to dump the instruction at the current IP such as:
> (gdb) x /10i $eip
> 
> I get this - which means it's not actually reading or displaying the memory 
> properly, since those look to be what you would see if it was all 0 in 
> memory (or maybe it's all 0xff - whichever).l
> 
> 0xe05f: add    %al,(%eax)

qemu doesn't report memory errors to GDB.  It reports -1 values
instead.  This is annoying.  I think I posted a patch for it once and
never followed up when it was ignored.

It might be reading the wrong address; it might be confused due to
segmenting; it might be looking at something that would require a TLB
fault.

> #4) Can you use gdb to debug and set breakpoints on binary code you don't 
> have any source code or other file for the binary, except the binary file 
> itself? Everything I've read so far on GDB (and especially any GDB Gui 
> front end) seems to suggest it's not possible. That would really suck.

Sure you can.  It will just work.

-- 
Daniel Jacobowitz
CodeSourcery