Linux内核模块编程指南：入门与实践

linux

kernel

需积分: 2 140 浏览量更新于2024-06-25 收藏 1.13MB PDF 举报

身份认证购VIP最低享 7 折!

领优惠券(最高得80元）

《Linux内核模块编程指南》是由Peter Jay Salzman、Michael Burian、Ori Pomerantz、Bob Mottram和Jim Huang共同编写的开源书籍，遵循Open Software License 3.0版本进行发布和授权。该书的目标是为读者提供关于如何编写和理解Linux内核模块的实用指导，无论是在个人或商业环境中使用，只要保持版权声明完整且遵循协议即可。本书的核心内容包括以下几个部分： 1. 介绍：作者介绍了这本书的创作背景和目标，解释了什么是内核模块，以及为什么要学习和创建它们。同时，还讨论了内核模块包的构成，以及读者是否需要下载和编译整个内核来加载模块，以及在开始编程前的准备工作。 2. 头文件：这部分介绍了内核模块编程中使用的头文件，这是理解和编写模块的基础，因为它们定义了模块可以访问的函数和数据结构。 3. 示例：书中提供了多个示例，如简单的"Hello World"模块，展示了如何定义基本的模块入口点（`__init`和`__exit`宏），处理命令行参数，以及模块可能跨越多个文件的设计。还有涉及字符设备驱动的部分，如`file_operations`结构，设备注册等，这些都是实现硬件交互的重要部分。 4. 预备知识：这部分深入探讨了模块在内核中的生命周期，包括模块如何开始和结束执行，以及模块可利用的函数和操作空间（用户空间与内核空间、命名空间和代码空间）。此外，对于驱动程序开发者来说，理解设备驱动程序的`file_operations`结构及其在文件系统中的作用至关重要。 5. 字符设备驱动：章节详细讲解了如何设计和实现字符设备驱动，包括文件描述符操作（如打开、读写和关闭）的处理，以及设备的注册过程。《Linux内核模块编程指南》旨在帮助读者掌握模块开发的基本原理和实践技巧，无论你是初学者还是经验丰富的开发者，都能从中受益匪浅。通过阅读这本书，你将了解到如何有效地将用户空间的逻辑无缝地集成到内核中，从而扩展和优化Linux系统的功能。

资源详情

资源推荐

8 MODULE_LICENSE("GPL");

9 MODULE_AUTHOR("LKMPG");

10 MODULE_DESCRIPTION("A sample driver");

12 static int __init init_hello_4(void)

13 {

14 pr_info("Hello, world 4\n");

15 return 0;

16 }

18 static void __exit cleanup_hello_4(void)

19 {

20 pr_info("Goodbye, world 4\n");

21 }

23 module_init(init_hello_4);

24 module_exit(cleanup_hello_4);

4.5 Passing Command Line Arguments to a Module

Modules can take command line arguments, but not with the argc/argv you

might be used to.

To allow arguments to be passed to your module, declare the variables that

will take the values of the command line arguments as global and then use the

module_param() macro, (deﬁned in include/linux/moduleparam.h) to set the

mechanism up. At runtime, insmod will ﬁll the variables with any command line

arguments that are given, like insmod mymodule.ko myvariable=5. The vari-

able declarations and macros should be placed at the beginning of the module

for clarity. The example code should clear up my admittedly lousy explanation.

The module_param() macro takes 3 arguments: the name of the variable,

its type and permissions for the corresponding ﬁle in sysfs. Integer types can

be signed as usual or unsigned. If you’d like to use arrays of integers or strings

see module_param_array() and module_param_string().

1 int myint = 3;

2 module_param(myint, int, 0);

Arrays are supported too, but things are a bit diﬀerent now than they were

in the olden days. To keep track of the number of parameters you need to pass

a pointer to a count variable as third parameter. At your option, you could also

ignore the count and pass NULL instead. We show both possibilities here:

1 int myintarray[2];

2 module_param_array(myintarray, int, NULL, 0); /* not interested in count */

4 short myshortarray[4];

5 int count;

6 module_param_array(myshortarray, short, &count, 0); /* put count into "count"

variable */,→

A good use for this is to have the module variable’s default values set, like

a port or IO address. If the variables contain the default values, then perform

autodetection (explained elsewhere). Otherwise, keep the current value. This

will be made clear later on.

Lastly, there is a macro function, MODULE_PARM_DESC(), that is used to

document arguments that the module can take. It takes two parameters: a

variable name and a free form string describing that variable.

1 /*

2 * hello-5.c - Demonstrates command line argument passing to a module.

3 */

4 #include <linux/init.h>

5 #include <linux/kernel.h> /* for ARRAY_SIZE() */

6 #include <linux/module.h>

7 #include <linux/moduleparam.h>

8 #include <linux/printk.h>

9 #include <linux/stat.h>

11 MODULE_LICENSE("GPL");

13 static short int myshort = 1;

14 static int myint = 420;

15 static long int mylong = 9999;

16 static char *mystring = "blah";

17 static int myintarray[2] = { 420, 420 };

18 static int arr_argc = 0;

20 /* module_param(foo, int, 0000)

21 * The first param is the parameters name.

22 * The second param is its data type.

23 * The final argument is the permissions bits,

24 * for exposing parameters in sysfs (if non-zero) at a later stage.

25 */

26 module_param(myshort, short, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);

27 MODULE_PARM_DESC(myshort, "A short integer");

28 module_param(myint, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);

29 MODULE_PARM_DESC(myint, "An integer");

30 module_param(mylong, long, S_IRUSR);

31 MODULE_PARM_DESC(mylong, "A long integer");

32 module_param(mystring, charp, 0000);

33 MODULE_PARM_DESC(mystring, "A character string");

35 /* module_param_array(name, type, num, perm);

36 * The first param is the parameter's (in this case the array's) name.

37 * The second param is the data type of the elements of the array.

38 * The third argument is a pointer to the variable that will store the number

39 * of elements of the array initialized by the user at module loading time.

40 * The fourth argument is the permission bits.

41 */

42 module_param_array(myintarray, int, &arr_argc, 0000);

43 MODULE_PARM_DESC(myintarray, "An array of integers");

45 static int __init hello_5_init(void)

46 {

47 int i;

12 make -C /lib/modules/$(shell uname -r)/b uild M=$(PWD) modules

14 clean:

15 make -C /lib/modules/$(shell uname -r)/b uild M=$(PWD) clean

This is the complete makeﬁle for all the examples we have seen so far. The

ﬁrst ﬁve lines are nothing special, but for the last example we will need two

lines. First we invent an object name for our combined module, second we tell

make what object ﬁles are part of that module.

4.7 Building modules for a precompiled kernel

Obviously, we strongly suggest you to recompile your kernel, so that you can

enable a number of useful debugging features, such as forced module unloading

(MODULE_FORCE_UNLOAD): when this option is enabled, you can force the kernel

to unload a module even when it believes it is unsafe, via a sudo rmmod -f module

command. This option can save you a lot of time and a number of reboots dur-

ing the development of a module. If you do not want to recompile your kernel

then you should consider running the examples within a test distribution on a

virtual machine. If you mess anything up then you can easily reboot or restore

the virtual machine (VM).

There are a number of cases in which you may want to load your module

into a precompiled running kernel, such as the ones shipped with common Linux

distributions, or a kernel you have compiled in the past. In certain circumstances

you could require to compile and insert a module into a running kernel which

you are not allowed to recompile, or on a machine that you prefer not to reboot.

If you can’t think of a case that will force you to use modules for a precompiled

kernel you might want to skip this and treat the rest of this chapter as a big

footnote.

Now, if you just install a kernel source tree, use it to compile your kernel

module and you try to insert your module into the kernel, in most cases you

would obtain an error as follows:

insmod: ERROR: could not insert module poet.ko: Invalid module format

Less cryptic information is logged to the systemd journal:

kernel: poet: disagrees about version of symbol module_layout

In other words, your kernel refuses to accept your module because version

strings (more precisely, version magic, see include/linux/vermagic.h) do not

match. Incidentally, version magic strings are stored in the module object in

the form of a static string, starting with vermagic:. Version data are inserted

in your module when it is linked against the kernel/module.o ﬁle. To inspect

version magics and other strings stored in a given module, issue the command

modinfo module.ko:

剩余122页未读，继续阅读

清竹小雨

粉丝: 132
资源: 41

会员权益专享

Linux内核模块编程指南：入门与实践

The Linux Kernel Module Programming Guide 2.6 中文版+英文版

The_Linux_Kernel_Module_Programming_Guide_2.6中文版

Linux内核驱动模块编程指南 (内核版本2.2, 2.4)The Linux Kernel Module Programming Guide CHS

The Linux Kernel Module Programming Guide最新

The Linux Kernel Module Programming Guide

linux device driver3 ldd3 code

Linux驱动程序开发资料汇集

操作系统的开发是一项复杂而深奥的工作，涉及到计算机科学中的许多核心概念和技术 下面是操作系统开发的一些关键方面和步骤： ###

Capgemini-生成式人工智能与营销角色的演变&CMO的策略（英）-2023(1).pdf

智慧园区-数字孪生智能可视运营平台解决方案两份文件.pptx

navicat - navicat mac en - version 16 - User Guide

tdm64-gcc-10.3.0.exe

古镇智慧旅游建设方案.pptx

XDMA-AXI-LITE接口转普通接口

ArcaneFire：2022年大中华区医药行业薪酬报告.pdf

2024年东南亚丁酸衍生物市场深度研究及预测报告.pdf

2023自然系旅游出行白皮书-娇韵诗&马蜂窝.pdf

2024年东南亚电流敏感电阻器市场深度研究及预测报告.pdf

2024年东南亚电热挡风玻璃市场深度研究及预测报告.pdf

卫生健康行业数据分类参考表.pdf

会员权益专享

最新资源

操作系统的开发是一项复杂而深奥的工作，涉及到计算机科学中的许多核心概念和技术下面是操作系统开发的一些关键方面和步骤： ###