debugging in linux

debugging in linux

[Hernan]

Hello,

I'm trying to debug a program (without debug information) with gdb but I 
can't do some things:

1) How can I run step by step,
2) see the registers values (including eip),
3) make a dump of memory

I'm running code that starts in 0x80003c0 and when I try disas 0x80003c0 I 
get "No function contains specified address".

The executable is a test that I'm doing I change the elf entry point and 
put some code there.

Is there a softice like debugger for linux? where can I get it?
Thanks in advance!

Hernan

Re: debugging in linux

[lx]

On Sat, 14 Sep 2002 11:31:05 -0300
Hernan <beri@ciudad.com.ar> wrote:

> Hello,
> 
> I'm trying to debug a program (without debug information) with gdb but I 
> can't do some things:
> 
> 1) How can I run step by step,
> 2) see the registers values (including eip),
> 3) make a dump of memory
> 
> I'm running code that starts in 0x80003c0 and when I try disas 0x80003c0 I 
> get "No function contains specified address".

try 'objdump -d'

> The executable is a test that I'm doing I change the elf entry point and 
> put some code there.
> 
> Is there a softice like debugger for linux? where can I get it?

no. linux. 'ald' might serve your purpose...
url re http://linuxassembl.org

hp

-- 
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    software patents  http://petition.eurolinux.org/pr/pr17.html
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linking with ld

[Mateusz Srebrny]

Hi,

I have question about ld.
Precisely: 
I have an ELF object (produced by nasm) defining global procedure named
start.
I want to link it with object made by 'gcc -c' on file loking like this:

#include <stdio.h>

extern void start(void);

int main() {
  start();
  return 0;
}


I tried 'ld main.o start.o -o main -lc'...
it complained sth about not defining _start label, and then refused to
execute main file (which was produced despite ld warnings)...

I wanted to do it with ld, 'couse I thought that linker is to link
things...
Of course linking it with gcc works, but again I thought that compiler
is to compile things to objects...

and the info for ld doesn't offer help in the matter... (at least I
don't see it there)

I would be grateful for your help...
	Mateusz Srebrny

PS the question "why do I want to link a nasm object with a C one?" is
very difficult to answer... i just have to do it...

Re: linking with ld

[Maciej Hrebien]

Mateusz Srebrny wrote:
> 
> Hi,
> 
> I have question about ld.
> Precisely:
> I have an ELF object (produced by nasm) defining global procedure named
> start.
> I want to link it with object made by 'gcc -c' on file loking like this:
> 
> #include <stdio.h>
> 
> extern void start(void);
> 
> int main() {
>   start();
>   return 0;
> }
> 
> I tried 'ld main.o start.o -o main -lc'...

You can link it using gcc, not ld directly like this: gcc -o mail
main.o start.o. It should work just fine.

> it complained sth about not defining _start label, and then refused to
> execute main file (which was produced despite ld warnings)...

_start is the default entry point. If You won't create any global label
named _start in Your code then the ld doesn't know what to put in ELF
header as a starting point. You may set it explicitly using ld's -e
option which i think is the good solution if You can't link with gcc
like in above example.
 
> I wanted to do it with ld, 'couse I thought that linker is to link
> things...
> Of course linking it with gcc works, but again I thought that compiler
> is to compile things to objects...

gcc works with ld. gcc sends its results to ld.
 
> and the info for ld doesn't offer help in the matter... (at least I
> don't see it there)
> 
> I would be grateful for your help...
>         Mateusz Srebrny
> 
> PS the question "why do I want to link a nasm object with a C one?" is
> very difficult to answer... i just have to do it...

-- 
Maciej Hrebien