The Linux Kernel Module Programming 的一个Hello程序。 The Linux Kernel Module Programming Guide：http://www.tldp.org/LDP/lkmpg/2.6/html/index.html

helloLKMP.c

/* From: http://www.tldp.org/LDP/lkmpg/2.6/html/x279.html */

/*
 * The following license idents are currently accepted as indicating free
 * software modules
 *
 *	"GPL"				[GNU Public License v2 or later]
 *	"GPL v2"			[GNU Public License v2]
 *	"GPL and additional rights"	[GNU Public License v2 rights and more]
 *	"Dual BSD/GPL"			[GNU Public License v2
 *					 or BSD license choice]
 *	"Dual MIT/GPL"			[GNU Public License v2
 *					 or MIT license choice]
 *	"Dual MPL/GPL"			[GNU Public License v2
 *					 or Mozilla license choice]
 *
 * The following other idents are available
 *
 *	"Proprietary"			[Non free products]
 *
 * There are dual licensed components, but when running with Linux it is the
 * GPL that is relevant so this is a non issue. Similarly LGPL linked with GPL
 * is a GPL combined work.
 *
 * This exists for several reasons
 * 1.	So modinfo can show license info for users wanting to vet their setup 
 *	is free
 * 2.	So the community can ignore bug reports including proprietary modules
 * 3.	So vendors can do likewise based on their own policies
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>

#define DRIVER_AUTHOR "icecream <creamidea@gmail.com>"
#define DRIVER_DESC "A sample driver"

static int __init hello_init(void) 
{
  printk("Hello, icecream!\n");

  // 调试信息级别
  printk("Hello, icecream!\n");
  printk(KERN_ERR "kernel error!\n");
  printk(KERN_INFO "kernel information!\n");
  printk("KERN_ERR in define kernel error!\n"); /* This is invalid */
  printk("<3> num-kernel error\n");
  /* printk(<3>"out num-kernel error1!\n"); /\* This is error *\/ */
  printk(KERN_DEBUG "debug information!\n");
  return 0;
}

static void __exit hello_exit(void)
{
  printk("Exit the driver module!\n");
}

module_init(hello_init); 	/* enter */
module_exit(hello_exit);	/* out */

/*  
 *  You can use strings, like this:
 */

/* 
 * Get rid of taint message by declaring code as GPL. 
 */
MODULE_LICENSE("Dual BSD/GPL");

/*
 * Or with defines, like this:
 */
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);

/*  
 *  This module uses /dev/testdevice.  The MODULE_SUPPORTED_DEVICE macro might
 *  be used in the future to help automatic configuration of modules, but is 
 *  currently unused other than for documentation purposes.
 */
MODULE_SUPPORTED_DEVICE("Test Device");