Linux内核模块(Module)的单独编译

176人浏览 2024-06-06 14:45:11

1.模块文件

/*
* file name: hello.c
*/

#include<linux/module.h>

#include<linux/init.h>                                                          

#include<linux/moduleparam.h>

MODULE_AUTHOR("Kevin Taylor");
MODULE_LICENSE("GPL");

static int nbr = 10; 
module_param(nbr, int, S_IRUGO);

static int __init hello_init(void)
{
   int i;

   printk(KERN_ALERT"Init hello mudule...\n");

   for(i=0;i<nbr;i++)
   {   
       printk(KERN_ALERT"Hello, how are you? %d\n", i); 
   }   

   return 0;
}

static void __exit hello_exit(void)
{
   printk(KERN_ALERT"Exit hello mudule...\n");
   printk(KERN_ALERT"I come from hello's module, I have been unload.\n");
}

module_init(hello_init);
module_exit(hello_exit);

MODULE_DESCRIPTION("A Simple Hello World");
MODULE_ALIAS("A simplest module");

2.Makefile

#makefile for the hello.c                                                       
obj-m := hello.o
CURRENT_PATH := $(shell pwd)
LINUX_KERNEL := $(shell uname -r)
LINUX_KERNEL_PATH := /usr/src/linux-headers-$(LINUX_KERNEL)
all:
   $(MAKE) -C $(LINUX_KERNEL_PATH) M=$(CURRENT_PATH) modules
clean:
   rm *.ko
   rm *.o

3.编译模块

make1

编译成功会输出如下信息：

make -C /usr/src/linux-headers-4.15.0-29-generic M=/home/yumo/Learn/driver/modules modules
make[1]: Entering directory '/usr/src/linux-headers-4.15.0-29-generic'
 CC [M]  /home/yumo/Learn/driver/modules/hello.o
 Building modules, stage 2.
 MODPOST 1 modules
 CC      /home/yumo/Learn/driver/modules/hello.mod.o
 LD [M]  /home/yumo/Learn/driver/modules/hello.ko
make[1]: Leaving directory '/usr/src/linux-headers-4.15.0-29-generic'

4.加载模块到内核中

sudo insmod ./hello.ko

5.验证模块是否加载成功

lsmod # 查看所有已加载的模块

6.加载模块时传递参数

sudo insmod hello.ko nbr=41

查看最近的8条日志信息：dmesg | tail -8

[16331.599330] Hello, how are you? 9
[18297.411389] Exit hello mudule...
[18297.411394] I come from hello's module, I have been unload.
[18330.125440] Init hello mudule...
[18330.125450] Hello, how are you? 0
[18330.125453] Hello, how are you? 1
[18330.125456] Hello, how are you? 2
[18330.125459] Hello, how are you? 3

在加载模块时动态设置了模块文件中的变量nbr(在模块文件中默认值为10)，从打印的日志信息可以看出，初始化函数中循环只执行了4次，说明加载模块时传递的参数已成功。

7.查看模块信息

sudo modinfo hello.ko1

输出的模块信息

filename:       /home/yumo/Learn/driver/modules/hello.ko
alias:          A simplest module
description:    A Simple Hello World
license:        GPL
author:         Kevin Taylor
srcversion:     A9C1413760EC5E7C4FD9DF6
depends:        
retpoline:      Y
name:           hello
vermagic:       4.15.0-29-generic SMP mod_unload 
parm:           nbr:int

8.查看内核的日志信息

dmesg # 查看当前所有的内核日志信息
dmesg | tail -12  # 查看内核最近输出的12条日志信息12

最近的12条内核日志信息

[15645.089201] I come from hello's module, I have been unload.
[16331.599309] Init hello mudule...
[16331.599316] Hello, how are you? 0
[16331.599318] Hello, how are you? 1
[16331.599320] Hello, how are you? 2
[16331.599321] Hello, how are you? 3
[16331.599323] Hello, how are you? 4
[16331.599324] Hello, how are you? 5
[16331.599326] Hello, how are you? 6
[16331.599327] Hello, how are you? 7
[16331.599329] Hello, how are you? 8
[16331.599330] Hello, how are you? 9

dmesg小结

执行dmesg命令用于查询内核的日志信息，方括号中的内容为time stamp，该时间戳默认是系统从开机到输出该条日志信息时的运行时间，以秒为单位。
以当前时间的为时间戳显示时间信息：dmesg -T

[Wed Aug  1 10:17:34 2018] Init hello mudule...
[Wed Aug  1 10:17:34 2018] Hello, how are you? 0
[Wed Aug  1 10:17:34 2018] Hello, how are you? 1

3.显示系统运行时间以及打印两条日志信息的时间间隔

[16331.599309 <  686.510108>] Init hello mudule...
[16331.599316 <    0.000007>] Hello, how are you? 0
[16331.599318 <    0.000002>] Hello, how are you? 1
[16331.599320 <    0.000002>] Hello, how are you? 2

4.显示最近输出的n条日志信息：dmesg | tail -n

5.以上参数可以混合使用，如：

[Wed Aug  1 10:06:19 2018 < 5352.292092>] I come from hello's module, I have been unload.
[Wed Aug  1 10:17:45 2018 <  686.510108>] Init hello mudule...
[Wed Aug  1 10:17:45 2018 <    0.000007>] Hello, how are you? 0
[Wed Aug  1 10:17:45 2018 <    0.000002>] Hello, how are you? 1
[Wed Aug  1 10:17:45 2018 <    0.000002>] Hello, how are you? 2
[Wed Aug  1 10:17:45 2018 <    0.000001>] Hello, how are you? 3
[Wed Aug  1 10:17:45 2018 <    0.000002>] Hello, how are you? 4
[Wed Aug  1 10:17:45 2018 <    0.000001>] Hello, how are you? 5
[Wed Aug  1 10:17:45 2018 <    0.000002>] Hello, how are you? 6
[Wed Aug  1 10:17:45 2018 <    0.000001>] Hello, how are you? 7
[Wed Aug  1 10:17:45 2018 <    0.000002>] Hello, how are you? 8
[Wed Aug  1 10:17:45 2018 <    0.000001>] Hello, how are you? 9