模块可以接受命令行参数，但不是使用你可能熟悉的argc/argv方式。
要允许将参数传递给你的模块，请将用于接收命令行参数值的变量声明为全局变量，然后使用module_param()宏，（定义在linux/moduleparam.h）来设置该机制。在运行时，insmod 将使用给定的任何命令行参数填充这些变量，例如 ./insmod mymodule.ko myvariable=5。为了清晰起见，变量声明和宏应放在模块的开头。示例代码应该可以澄清我承认很糟糕的解释。
该module_param()宏接受 3 个参数：变量名、其类型以及 sysfs 中相应文件的权限。整数类型可以像往常一样有符号或无符号。如果你想使用整数或字符串数组，请参阅module_param_array()和module_param_string().
int myint = 3; module_param(myint, int, 0); |
也支持数组，但现在的情况与 2.4 版本时略有不同。为了跟踪参数的数量，你需要将指向计数变量的指针作为第三个参数传递。你可以选择忽略计数并传递 NULL。我们在这里展示了这两种可能性
int myintarray[2]; module_param_array(myintarray, int, NULL, 0); /* not interested in count */ int myshortarray[4]; int count; module_parm_array(myshortarray, short, , 0); /* put count into "count" variable */ |
一个好的用法是设置模块变量的默认值，例如端口或 IO 地址。如果变量包含默认值，则执行自动检测（在其他地方解释）。否则，保持当前值。这一点将在后面明确说明。
最后，还有一个宏函数，MODULE_PARM_DESC()，用于记录模块可以接受的参数。它接受两个参数：变量名和一个描述该变量的自由格式字符串。
示例 2-7. hello-5.c
/*
* hello-5.c - Demonstrates command line argument passing to a module.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/stat.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Peter Jay Salzman");
static short int myshort = 1;
static int myint = 420;
static long int mylong = 9999;
static char *mystring = "blah";
static int myintArray[2] = { -1, -1 };
static int arr_argc = 0;
/*
* module_param(foo, int, 0000)
* The first param is the parameters name
* The second param is it's data type
* The final argument is the permissions bits,
* for exposing parameters in sysfs (if non-zero) at a later stage.
*/
module_param(myshort, short, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
MODULE_PARM_DESC(myshort, "A short integer");
module_param(myint, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
MODULE_PARM_DESC(myint, "An integer");
module_param(mylong, long, S_IRUSR);
MODULE_PARM_DESC(mylong, "A long integer");
module_param(mystring, charp, 0000);
MODULE_PARM_DESC(mystring, "A character string");
/*
* module_param_array(name, type, num, perm);
* The first param is the parameter's (in this case the array's) name
* The second param is the data type of the elements of the array
* The third argument is a pointer to the variable that will store the number
* of elements of the array initialized by the user at module loading time
* The fourth argument is the permission bits
*/
module_param_array(myintArray, int, &arr_argc, 0000);
MODULE_PARM_DESC(myintArray, "An array of integers");
static int __init hello_5_init(void)
{
int i;
printk(KERN_INFO "Hello, world 5\n=============\n");
printk(KERN_INFO "myshort is a short integer: %hd\n", myshort);
printk(KERN_INFO "myint is an integer: %d\n", myint);
printk(KERN_INFO "mylong is a long integer: %ld\n", mylong);
printk(KERN_INFO "mystring is a string: %s\n", mystring);
for (i = 0; i < (sizeof myintArray / sizeof (int)); i++)
{
printk(KERN_INFO "myintArray[%d] = %d\n", i, myintArray[i]);
}
printk(KERN_INFO "got %d arguments for myintArray.\n", arr_argc);
return 0;
}
static void __exit hello_5_exit(void)
{
printk(KERN_INFO "Goodbye, world 5\n");
}
module_init(hello_5_init);
module_exit(hello_5_exit); |
我建议尝试使用这段代码
satan# insmod hello-5.ko mystring="bebop" mybyte=255 myintArray=-1 mybyte is an 8 bit integer: 255 myshort is a short integer: 1 myint is an integer: 20 mylong is a long integer: 9999 mystring is a string: bebop myintArray is -1 and 420 satan# rmmod hello-5 Goodbye, world 5 satan# insmod hello-5.ko mystring="supercalifragilisticexpialidocious" \ > mybyte=256 myintArray=-1,-1 mybyte is an 8 bit integer: 0 myshort is a short integer: 1 myint is an integer: 20 mylong is a long integer: 9999 mystring is a string: supercalifragilisticexpialidocious myintArray is -1 and -1 satan# rmmod hello-5 Goodbye, world 5 satan# insmod hello-5.ko mylong=hello hello-5.o: invalid argument syntax for mylong: 'h' |