Inject to Linux 2.6 问题解决 :-)

最新推荐文章于 2024-11-17 02:32:28 发布

neohuo

最新推荐文章于 2024-11-17 02:32:28 发布

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分类专栏：课题 * 工作文章标签： linux struct file module makefile shell

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本文介绍了一个简单的字符设备驱动程序的实现过程，包括源代码及如何编译和加载该驱动。通过对核心函数的解析，帮助读者理解Linux设备驱动的基本概念。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

   首先看看我自己编的一个驱动模块,下面是源码: asdf.c
#ifndef __KERNEL__
#define __KERNEL__
#endif
#ifndef MODULE
#define MODULE
#endif
#include <linux/config.h>
#include<linux/module.h>                                                                             MODULE_LICENSE("GPL");
#ifdef CONFIG_SMP
#define __SMP__
#endif

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <asm/uaccess.h>
#include "asdf.h"
static int asdf_init()
{
    printk("hi,this's a simple device file!/n");
    asdf_major=register_chrdev(0,"A Simple Device File",&asdf_ops);
    if(asdf_major<0) return asdf_major;
        printk("The major is %d/n",asdf_major);
    return 0;
}
static void asdf_exit()
{
    unregister_chrdev(asdf_major,"A Simple Device File");
    printk("A Simple Device has been removed,Bye/n");
}
static int asdf_open(struct inode *inode,struct file *filp)
{
    printk("^_^:open %s/n",current->comm);
    return 0;
}
static int asdf_release(struct inode *inode,struct file *filp)
{
    printk("^_^:close/n");
    return 0;
}
static ssize_t asdf_read(struct file *filp,char *buf,size_t count,loff_t *f_pos)
{
    loff_t pos;
    pos = *f_pos;
    if((pos==4096)||(count>4096)) return 0;
    pos+=count;
    if(pos>4096){
    count-=(pos-4096);
    pos=4096;
    }
    if(copy_to_user(buf,asdf_body+*f_pos,count)) return -EFAULT;
    *f_pos=pos;
        return count;
}
static ssize_t asdf_write(struct file *filp,const char *buf,size_t count,loff_t *f_pos)
{
    loff_t pos;
    pos = *f_pos;
    if((pos==4096)||(count>4096)) return 0;
        pos+=count;
        if(pos>4096){
        count-=(pos-4096);
        pos=4096;
        }
        if(copy_from_user(asdf_body+*f_pos,buf,count)) return -EFAULT;
        *f_pos=pos;
        return count;
}
static loff_t asdf_lseek(struct file *file,loff_t offset,int orig)
{
    loff_t pos;
    pos=file->f_pos;
        switch(orig){
    case 0: pos = offset;
        break;
    case 1: pos += offset;
        break;
    case 2: pos = 4096 + offset;
        break;
    default:
        return -EINVAL;
    }
       if((pos>4096)||(pos<0)){
    printk("^_^:lseek error %d/n",pos);
    return -EINVAL;
    }
    return file->f_pos = pos;
}
module_init(asdf_init);
module_exit(asdf_exit);

asdf.h如下:
static int asdf_open(struct inode *inode,struct file *filp);
static int asdf_release(struct inode *inode,struct file *filp);
static ssize_t asdf_read(struct file *filp,char *buf,size_t count,loff_t *f_pos);
static ssize_t asdf_write(struct file *filp,const char *buf,size_t count,loff_t *f_pos);
static loff_t asdf_lseek(struct file *file,loff_t offset,int orig);

struct file_operations asdf_ops={
    .open=    asdf_open,
       .release=   asdf_release,
    .read=    asdf_read,
    .write=   asdf_write,
    .llseek= asdf_lseek,
        };

static asdf_major;
static u8 asdf_body[4096]="asdf_body,this message come from the kernel/n";

完成之后,使用2.4编译方法编译成模块,能生成asdf.o文件,但是无法加载到内核,必须错新编写一个Makefile来编译:
obj-m   :=asdf.o
KDIR    :=/lib/modules/$(shell uname -r)/build
PWD     :=$(shell pwd)

default :
         $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
clean:
        rm -f *.o *.ko *.mod.c *~
编译通过后查看一下,发现生成asdf.o,asdf.mod.c和asdf.ko,看了新版的LINUX驱动程序发现*.ko是由asdf.o和asdf.mod.c 生成的 ,然后就可以按这老步骤insmod asdf.ko -> mknod /dev/asdf c 254 0

下面是一个简单的测试程序,可供参考:
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
void main()
{
int asdf;
char buf[1024];
asdf=open("/dev/asdf",O_RDWR);
if(asdf==-1)
{
printf("cant open file/n");
exit(0);
}
read(asdf,buf,1024);
printf("the message from asdf dev is: %s/n",buf);
close(asdf);
}