Enable Debugging with GDB in Edge Microvisor Toolkit Developer Node

In a mutable developer node installed from an ISO image, you can enable unrestricted debugging. To debug any process in the system, you need to change the value of the kernel.yama.ptrace_scope configuration parameter of Yama - Linux Security Module (LSM) that does Discretionary Access Control of kernel related functions. The ptrace_scope parameter defines whether selected processes can be debugged with ptrace (process tracing).

1. Configure Yama ptrace settings.

   Open the 99-yama-ptrace.conf configuration file with a chosen editor:

   sudo vi /lib/sysctl.d/99-yama-ptrace.conf
   

   Add or modify the following line:

   kernel.yama.ptrace_scope = 0
   

   Setting the parameter’s value to 0 allows you to debug any process in the system.

2. Rebuild initramfs and reboot the device.

   sudo dracut --force
   sudo reboot
   

3. Verify the ptrace settings after reboot.

   sudo sysctl kernel.yama.ptrace_scope
   

   If properly set, it should return 0.

4. Install GDB - the GNU Project Debugger.

   sudo apt install gdb
   

5. Compile your program with debug symbols.

   Compile your code, using gcc with the -g option, which enables extra debugging information for GDB to process, and the -o option, that allows you to save the output to a specified file.

   gcc -g sum.c -o sum_debug
   

6. Run GDB and debug the output file.

   To debug the sum_debug output file you need to specify it as an argument to gdb.

   gdb ./sum_debug
   

   Or, run the output file inside gdb using the file command.

   gdb
   file sum_debug
   

7. Now, you can set breakpoints and debug normally.