Linux kernel module: Add entry to debugfs and a read/write file.

Goal

This module will create Ray_DBG directory in debugfs and create a file REG for read/write. it's similar to previous module(create /proc/Ray), but easier to use and need less line of code.

 

Code

Makefile

Usage

1. Insert module 

$>insmod test_module.ko
$>dmesg | tail
[7501255.251763] Create Ray_DBG !
[7501255.251776] Create REG debug !

2. Mount debugfs 

$>mount -t debugfs none /sys/kernel/debug

3. Read data

$>cat /sys/kernel/debug/Ray_DBG/REG
$>0x000000aa

4. Write data 

$>echo 0xff>  /sys/kernel/debug/Ray_DBG/REG 
$>cat /sys/kernel/debug/Ray_DBG/REG 
$>0x000000ff

Reference

1. Kernel document: debugfs
2. Debugfs