param.c

对linux内核编程做了详细的解析和举例

/* param.c 
 * 
 * Receive command line parameters at module installation
 */

/* Copyright (C) 1998-99 by Ori Pomerantz */





/* The necessary header files */

/* Standard in kernel modules */
#include <linux/kernel.h>   /* We're doing kernel work */
#include <linux/module.h>   /* Specifically, a module */

/* Deal with CONFIG_MODVERSIONS */
#if CONFIG_MODVERSIONS==1
#define MODVERSIONS
#include <linux/modversions.h>
#endif        


#include <stdio.h>  /* I need NULL */


/* In 2.2.3 /usr/include/linux/version.h includes a 
 * macro for this, but 2.0.35 doesn't - so I add it 
 * here if necessary. */
#ifndef KERNEL_VERSION
#define KERNEL_VERSION(a,b,c) ((a)*65536+(b)*256+(c))
#endif



/* Emmanuel Papirakis:
 *
 * Prameter names are now (2.2) handled in a macro.
 * The kernel doesn't resolve the symbol names
 * like it seems to have once did.
 *
 * To pass parameters to a module, you have to use a macro
 * defined in include/linux/modules.h (line 176).
 * The macro takes two parameters. The parameter's name and
 * it's type. The type is a letter in double quotes.
 * For example, "i" should be an integer and "s" should
 * be a string.
 */


char *str1, *str2;


#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)
MODULE_PARM(str1, "s");
MODULE_PARM(str2, "s");
#endif


/* Initialize the module - show the parameters */
int init_module()
{
  if (str1 == NULL || str2 == NULL) {
    printk("Next time, do insmod param str1=<something>");
    printk("str2=<something>\n");
  } else
    printk("Strings:%s and %s\n", str1, str2);

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)
  printk("If you try to insmod this module twice,");
  printk("(without rmmod'ing\n");
  printk("it first), you might get the wrong"); 
  printk("error message:\n");
  printk("'symbol for parameters str1 not found'.\n");
#endif

  return 0;
}


/* Cleanup */
void cleanup_module()
{
}