GDB guide 2023

GDB is a tool that helps developers find and fix issues in their programs. In this guide, we’ll cover what it is, how to install it, its latest version, new features, and how to use it effectively. We’ll also talk about memory tagging and alternatives to GDB.

What is GDB?

GDB, the mighty GNU Debugger, stands as a beacon of brilliance and power in the vast realm of software development. With its unwavering capabilities, GDB takes on the noble task of aiding programmers and developers in their quest for bug-free code and flawless execution.

From the depths of its code-steeped heart, GDB emerges as a versatile and indomitable force, ready to conquer the darkest corners of any program.

Supported by a legion of programming languages, including Ada, C++, Fortran, and Rust, GDB fearlessly navigates the intricate labyrinth of software, unraveling mysteries and shedding light on the perplexing challenges that lie ahead.

You can find free online platforms to use a gdb compiler. One such platform is discussed in the article “Exploring online gdb compiler.”

How to Install GDB?

The installation process for GDB varies depending on your operating system:

  • On Linux:
  • You can use the command
    • sudo apt-get install libc6-dbg gdb valgrind
    • or
    • sudo apt-get update
    • followed by
    • sudo apt-get install gdb.
  • Alternatively, you can use pipx to install gdbgui.
  • On Windows:
  • Download and install MinGW, which distributes a Windows version of GDB.
  • Or, use gdbgui, which can be installed on Windows following the instructions on their website.

What is the Latest Version of GDB?

The latest version of GNU Debugger (GDB) is version 11.1. It is a source-level debugger compatible with many programming languages and Unix-like systems. To update your GDB installation to the latest version, you can download it from the GNU website, ensuring compatibility with your specific platform and version.

New Features in GDB 11.1

GDB version 11.1, released on September 12, 2021, introduces several new features and enhancements, including:

  • Initial support for memory tagging, especially for Arm’s AArch64 MTE memory tagging extension.
  • New command-line options like --early-init-command and --early-init-eval-command.
  • GDB/MI changes with new options for -break-insert and -dprintf-insert commands.
  • TUI improvements with mouse actions and key combinations.
  • Python enhancements, including new attributes and methods for Python support.

How to Use Memory Tagging in GDB

If your architecture supports memory tagging, like AArch64 MTE or SPARC ADI, GDB can help validate pointers against memory allocation tags. You can use commands like memory-tag print-logical-tag, memory-tag setatag, and memory-tag check to work with memory tags. These commands allow you to inspect and validate memory tagging in your running process.

What is AArch64 MTE?

AArch64 MTE, or Memory Tagging Extension, is a feature in the AArch64 Linux architecture, specifically designed for ARMv8.5-based processors. It enables software to access a 4-bit allocation tag for each 16-byte granule in the physical address space. This extension enhances memory safety by detecting memory safety violations and providing robustness against attacks attempting to subvert code.

How to Enable Memory Tagging Extension

Enabling Memory Tagging Extension depends on your operating system:

  • On Linux, refer to the official documentation on the website.
  • On Windows, consult the official documentation on the Microsoft Learn website.
  • For Android, follow the official documentation on the Android Open Source Project website.

Alternatives to GDB on Linux

There are several alternatives to GDB on Linux, including Emacs, DDD, Nemiver, Eclipse, Code::Blocks, NetBeans, and Anjuta. If you prefer a debugger with a visual studio feel, consider EDB (Evan’s Debugger), a free debugger with a plugin architecture for easy feature expansion.

Alternatives to GDB on Windows

Windows users have several alternatives to GDB, including WinDbg, Visual Studio Debugger, OllyDbg, x64dbg, and Immunity Debugger. EDB (Evan’s Debugger) is another option for Windows users looking for a debugger with a visual studio feel and plugin support.

How to Use Breakpoints in GDB

Breakpoints in GDB help you pause program execution at specific points. Here’s a brief guide:

  1. Set a breakpoint: Use the break command to set a breakpoint at a line, function, or instruction address.
  2. List breakpoints: View all breakpoints with info breakpoints.
  3. Delete a breakpoint: Remove a breakpoint with delete.
  4. Disable/enable a breakpoint: Use disable or enable.
  5. Set a condition: Attach a condition to a breakpoint with condition.
  6. Run your program: Start your program with run.
  7. Continue execution: After hitting a breakpoint, resume with continue.

How to Print Variable Values in GDB

To print a variable’s value in GDB, use the print or p command followed by the variable’s name. Ensure you’re in the variable’s scope by setting breakpoints where needed. Example: print x or p my_var.

GNU Debugger (GDB) is an invaluable tool for debugging programs across multiple programming languages and platforms. Understanding how to install, use, and leverage its features can significantly enhance your software development and debugging process. Additionally, exploring memory tagging and alternative debuggers can provide you with a broader perspective on debugging tools and techniques.

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