This document provides an overview of using the GNU Debugger (GDB) tool for debugging programs on an NVIDIA Jetson TX2 embedded system. It discusses setting breakpoints in code, running a program under GDB, examining variables and source code, and includes an example C code for demonstrating GDB commands. The document also briefly introduces concepts like stack memory and differences between arrays and stacks.

1. Tutorial 1
Fall 2022
Abdelrahman Elewah
SOFE 4590U: Embedded Systems

2. Agenda
• NVIDIA Jetson TX2.
• Stack memory
• The GNU Project Debugger GDB.
• Example for GDB tool
https://drive.google.com/file/d/13hOh0qr6DSyhv_fLIxxbC4LPR1CR6x8c/view?usp=sharing
• putty
https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html
Codes folder

3. NVIDIA Jetson TX2.

4. NVIDIA Jetson TX2
4
• NVIDIA Jetson TX2 developer Kit is an embedded system-on-module with dual-core ARM Cortex-A57, 8 GB
LPDDR4, and integrated 256-core Pascal GPU. It gives us an easy way to develop software and hardware for
the Jetson TX2 AI supercomputer on a module.
https://sirinsoftware.com/blog/the-arm-processor-a-r-and-m-categories-and-their-specifics/

5. In a nutshell
5
• The Jetson TX2 boards consists of an Ethernet port, an HDMI port to
the external HDMI display, a USB port that could connect to a USB
hub to a keyboard and mouse.
• If you are interested in more on the Jetson Series products, there
are many useful online documents available on the NVIDIA website.
For example, you can read through Jetson TX1 and TX2 Developer
Kits User Guide for more details.

6. Stack memory

7. Stack vs Array
7
https://www.geeksforgeeks.org/difference-between-stack-and-array/
Array

8. Stack Example
8
https://www.computerhope.com/jargon/s/stacover.htm
For example, we use to start with declaring variables at the
beginning of all programs.
Int a = 4; //line 1
Int b =5; //line 2
The stack is responsible for keeping tracking the running
memory in your application. When the program executes
integer b, it stacks this memory allocation on top of the first
memory allocation, where the first line of code executes.

9. Debugging
9
Debugging is the process of finding and resolving bugs (defects or problems that prevent
correct operation) within computer programs, software, or systems.
The GNU Debugger (GDB) is a portable debugger that runs on many Unix-like systems and
works for many programming languages, including Ada, C++, Objective-C, Free Pascal,
Fortran, and Go.
GNU Debugger allows you to inspect what the program is doing at a certain point during
execution.

10. Enabling built-in debugging support
10
• Normally, you would compile a program like:
• Now you add a -g option to enable built-in debugging support (which gdb needs):
gcc [flags] <source files> -o <output file>
gcc [other flags] -g <source files> -o <output file>

11. • The GNU Project Debugger GDB.

12. Code for GDB tutorial
12
#include <stdio.h>
void fun3(){
int fun3Var=30;
printf("fun3Var in fun3 = %dn",fun3Var);}
void fun2(){
int fun2Var=20;
printf("fun3Var in fun2 = %dn",fun2Var);
fun3();}
void fun1(){
int fun1Var=10;
printf("fun3Var in fun1 = %dn",fun1Var);
fun2();}
int main() {
int mainVar=1000;
printf("mainVar in main = %dn",mainVar);
fun1();
return 0;}
gcc -g code.c -o code
gdb code

13. 13
Setting Breakpoints
Breakpoints are points in your code at which gdb will stop and allow executing other gdb commands.
Set a breakpoint at the beginning of a function.
Example. Set a breakpoint at the beginning of main.
(gdb) b main
Set a breakpoint at a line of the current file during debugging.
Example. Set a breakpoint at line 35 while in file code.c
(gdb) b 7
Breakpoints

14. 14
Listing breakpoints.
Example. List all breakpoints which have been set so far in a debugging session.
(gdb) info b
Num Type Disp Enb Address What
1 breakpoint keep y 0x0040104f in main at code.c:14
2 breakpoint keep y 0x004010a7 in fun2 at code.c:8
Deleting a breakpoint.
Example. Delete the breakpoint at line 8
(gdb) delete 2
Help and Quitting Gdb
There is a help command, h and the command to quit gdb is q.
(gdb) h
(gdb) q
Breakpoints

15. 15
Start the program being debugged.
Example 1. The program is printch, which can take an optional command line argument. Start it running with no command line
argument.
(gdb) r
Execute a single statement.
If the statement is a function call, execute the entire function and return to the statement just after the call; that is, step over the
function.
(gdb) n
Execute a single statement.
If the statement is a function call, just single step into the function.
(gdb) s
Execute from the current point up to the next breakpoint
if there is one, otherwise execute until the program terminates.
(gdb) c
Execute the rest of the current function; that is, step out of the function.
(gdb) finish
Running the Program being Debugged

16. 16
Examining Variables
Print the value of a variable or expression.
Example 1. Print the value of a variable count
(gdb) p fun1Var
Print local variable
(gdb) info local
Print variable in another function
(gdb) f 1
List Source Code and the Next Statement
List lines of source code.
Example. List the next listsize number of lines of code. Note that listsize's value can be change with the set command.
(gdb) l
List lines of source code centered around a particular line.
Example. List the lines centered around line 41.
(gdb) l 41
Show the next statement that will be executed.
(gdb) where
Or
(gdb) bt
Show the entire assembly code
(gdb) disass

17. Thank you