Enable kernel debugging

This section describes kernel debugging features that are used to diagnose system and performance issues.

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Enable dynamic debug

The debugfs file system allows you to debug the kernel by enabling logs at runtime. When verifying a particular scenario, use the debugfs file system to enable logs for the specific time. By default, dynamic debug is disabled. To enable debugfs in the kernel, do the following:

1. Enable the CONFIG_DYNAMIC_DEBUG kernel configuration option.
2. Recompile and reflash the build.
3. To mount the debugfs file system, run the following commands:
   mount -o rw,remount /
   
   mount -t debugfs none /sys/kernel/debug
   
   1. Verify whether dynamic debug is enabled by checking that the following path exists:
      cd /sys/kernel/debug/dynamic_debug
      
   2. If the directory exists, verify the defined logs:
      cat /sys/kernel/debug/dynamic_debug/control
      
4. Enable debug logs for the files or functions that require debugging. For example:
   • To enable all debugfs logs in the mdp.c file, run the following command:
     echo 'file mdp.c +p' > /sys/kernel/debug/dynamic_debug/control
     
   • To enable the log at line 2921 in the mdp.c file, run the following command:
     echo 'file mdp.c line 2921 +p' > /sys/kernel/debug/dynamic_debug/control
     
5. Verify logs using the dmesg command or run the following command:
   cat /proc/kmsg
   
   For more information, see Documentation/dynamic-debug-howto.txt.

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Enable kernel debugging options

You can enable kernel configuration options to debug various issues such as memory leak, lock-related, and mutex problems. To see the available kernel debugging options, invoke menuconfig. For more information about kernel debugging options, see Configure the kernel The following are some debugging options: Kernel hacking [*] Kernel debugging [*] Detect Soft Lockups [ ] Collect scheduler statistics [*] Debug slab memory allocations [*] Memory leak debugging [*] Mutex debugging, deadlock detection [*] Spinlock debugging [*] Sleep-inside-spinlock checking [ ] kobject debugging [ ] Highmem debugging [ ] Compile the kernel with debug info