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- 2011-3-6
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- 1970-1-1
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1,hello:
最基本的hello world内核模块
make
sudo insmod hello.ko
dmesg |tail
sudo rmmod hello
- /*************** hello.c ***************/
- #include <linux/init.h>
- #include <linux/module.h>
- #include <linux/kernel.h>
- MODULE_LICENSE("Dual BSD/GPL");
- MODULE_AUTHOR("djwow");
- static int hello_init(void)
- {
- printk(KERN_ALERT "Hello, world!\n");
- return 0;
- }
- static void hello_exit(void)
- {
- printk(KERN_ALERT "Goodbye, My Dear World!\n");
- }
- module_init(hello_init);
- module_exit(hello_exit);
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makefile:- obj-m = hello.o
- KVERSION = $(shell uname -r)
- all:
- make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules
- clean:
- make -C /lib/modules/$(KVERSION)/build M=$(PWD) clean
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2,hello-1,hello-2:
hello-2导出了一个hello_data的全局变量,供hello-1中的模块使用。
先编译hello-2。并将目录下的Module.symvers拷贝到hello-1中。然后再编译hello-1。
然后先安装hello-2中的模块,再运行hello-1中的模块。
或者将hello-1中的KBUILD_EXTRA_SYMBOLS = /mnt/hgfs/MallocFreeIBM/Linux/10ten-hellokernel/demo/hello-2/Module.symvers中的/mnt/hgfs/MallocFreeIBM/Linux/10ten-hellokernel/demo/hello-2修改为你自己对应的hello-2的路径。
hello-1.c- #include <linux/init.h>
- #include <linux/module.h>
- #include <linux/kernel.h>
- MODULE_LICENSE("GPL");
- extern int hello_data;
- static int hello_init(void)
- {
- printk(KERN_ERR "hello,kernel!,this is hello module\n");
- printk(KERN_ERR "hello_data:%d\n",++hello_data);
- return 0;
- }
- static void hello_exit(void)
- {
- printk(KERN_ERR "hello_data:%d\n",--hello_data);
- printk(KERN_ERR "Leave hello module!\n");
- }
- module_init(hello_init);
- module_exit(hello_exit);
- MODULE_AUTHOR("djwow");
- MODULE_DESCRIPTION("This is hello module");
- MODULE_ALIAS("A simple example");
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hello_2.c- #include <linux/init.h>
- #include <linux/module.h>
- #include <linux/kernel.h>
- MODULE_LICENSE("GPL");
- unsigned int hello_data=100;
- EXPORT_SYMBOL(hello_data);
- static int hello_h_init(void)
- {
- hello_data+=5;
- printk(KERN_ERR "hello_data:%d\nhello kernel,this is hello_h module\n",hello_data);
- return 0;
- }
- static void hello_h_exit(void)
- {
- hello_data-=5;
- printk(KERN_ERR "hello_data:%d\nleave hello_h module\n",hello_data);
- }
- module_init(hello_h_init);
- module_exit(hello_h_exit);
- MODULE_AUTHOR("djwow.com");
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makefile- obj-m=hello_2.o
- KVERSION = $(shell uname -r)
- all:
- make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules
- clean:
- make -C /lib/modules/$(KVERSION)/build M=$(PWD) clean
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3,hello-param用于向模块动态传递参数
编译之后运行方法:
insmod hello who="world" times=5
- #include <linux/init.h>
- #include <linux/module.h>
- #include <linux/moduleparam.h>
-
- MODULE_LICENSE("Dual BSD/GPL");
- static char *who= "world";
- static int times = 1;
-
- module_param(times,int,S_IRUSR);
- module_param(who,charp,S_IRUSR);
- static int hello_init(void)
- {
- int i;
- for(i=0;i<times;i++)
- printk(KERN_ALERT "(%d) hello, %s!\n",i,who);
- return 0;
- }
- static void hello_exit(void)
- {
- printk(KERN_ALERT"Goodbye, %s!\n",who);
- }
- module_init(hello_init);
- module_exit(hello_exit);
复制代码 makefile:- obj-m = hello.o
- KVERSION = $(shell uname -r)
- all:
- make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules
- clean:
- make -C /lib/modules/$(KVERSION)/build M=$(PWD) clean
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4,kernel-client 通信demop 顺便演示了timer使用
先分别运行make编译好client和kernel程序。
然后,加载驱动:sudo insmod timer-kernel.ko
然后,
cat /proc/devices,查看second对应的主功能号,如251
sudo mknod /dev/second c 251 0
然后运行client:
./timer-client
client:- #include <stdio.h>
- #include <unistd.h>
- #include <fcntl.h>
- int main(void)
- {
- int fd, i;
- int data;
- fd = open("/dev/second",O_RDONLY);
- if (fd < 0)
- {
- printf("open /dev/second error\n");
- }
- for(i = 0; ; i++)
- {
- read(fd, &data, sizeof(data));
- printf("read /dev/second is %d\n",data);
- sleep(1);
- }
- close(fd);
- }
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makefile:- timer-client:timer-client.o
- gcc -o timer-client timer-client.o
- timer-client.o:timer-client.c
- gcc -c timer-client.c -o timer-client.o
- clean:
- rm -f *.o timer-client
复制代码 kernel:- #include <linux/module.h>
- #include <linux/types.h>
- #include <linux/fs.h>
- #include <linux/errno.h>
- #include <linux/mm.h>
- #include <linux/sched.h>
- #include <linux/init.h>
- #include <linux/cdev.h>
- #include <asm/io.h>
- #include <asm/system.h>
- #include <asm/uaccess.h>
- #include <linux/timer.h>
- #include <asm/atomic.h>
- #define SECOND_MAJOR 0
- static int second_major = SECOND_MAJOR;
- struct second_dev
- {
- struct cdev cdev;
- atomic_t counter;
- struct timer_list s_timer;
- };
- struct second_dev *second_devp;
- static void second_timer_handle(unsigned long arg)
- {
- mod_timer(&second_devp->s_timer, jiffies + HZ);
- atomic_inc(&second_devp->counter);
-
- printk(KERN_INFO "current jiffies is %ld\n",jiffies);
- }
- int second_open(struct inode *inode, struct file *filp)
- {
- init_timer(&second_devp->s_timer);
- second_devp->s_timer.function = &second_timer_handle;
- second_devp->s_timer.expires = jiffies + HZ;
-
- add_timer(&second_devp->s_timer);
- atomic_set(&second_devp->counter, 0);
- return 0;
- }
- int second_release(struct inode *inode, struct file *filp)
- {
- del_timer(&second_devp->s_timer);
-
- return 0;
- }
- static ssize_t second_read(struct file *filp, char __user *buf, size_t count,
- loff_t *ppos)
- {
- int counter;
-
- counter = atomic_read(&second_devp->counter);
- if (put_user(counter, (int *)buf))
- {
- return -EFAULT;
- }else
- {
- return sizeof(unsigned int);
- }
-
- }
- static const struct file_operations second_fops =
- {
- .owner = THIS_MODULE,
- .open = second_open,
- .release = second_release,
- .read = second_read,
- };
- static void second_setup_cdev(struct second_dev *dev, int index)
- {
- int err, devno = MKDEV(second_major, index);
- cdev_init(&dev->cdev, &second_fops);
- dev->cdev.owner = THIS_MODULE;
- dev->cdev.ops = &second_fops;
- err = cdev_add(&dev->cdev, devno, 1);
- if (err)
- {
- printk(KERN_NOTICE "Error %d add second%d", err, index);
- }
- }
- int second_init(void)
- {
- int ret;
- dev_t devno = MKDEV(second_major, 0);
-
- if (second_major)
- {
- ret = register_chrdev_region(devno, 1, "second");
- }else
- {
- ret = alloc_chrdev_region(&devno, 0, 1, "second");
- second_major = MAJOR(devno);
- }
- if (ret < 0)
- {
- return ret;
- }
-
- second_devp = kmalloc(sizeof(struct second_dev), GFP_KERNEL);
- if (!second_devp)
- {
- ret = -ENOMEM;
- goto fail_malloc;
- }
-
- memset(second_devp, 0, sizeof(struct second_dev));
-
- second_setup_cdev(second_devp, 0);
-
- return 0;
- fail_malloc:
- unregister_chrdev_region(devno, 1);
- return ret;
- }
- void second_exit(void)
- {
- cdev_del(&second_devp->cdev);
- kfree(second_devp);
- unregister_chrdev_region(MKDEV(second_major, 0), 1);
- }
- MODULE_AUTHOR("djwow");
- MODULE_LICENSE("Dual BSD/GPL");
- module_param(second_major, int, S_IRUGO);
- module_init(second_init);
- module_exit(second_exit);
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5,char_drv 通信demo
另外一个例子可以看我了另一篇文件
51456791
先运行make编译好kernel程序。
然后,加载驱动:sudo insmod char_drv.ko
然后,
cat /proc/devices,查看mem_dev对应的主功能号,如251
sudo mknod /dev/memdev0 c 251 0
然后运行client:
gcc -o test_char_drv test_char_drv.c
./test_char_drv
R3:- #include <stdio.h>
- #include <string.h>
- int main()
- {
- FILE *fp0 = NULL;
- char Buf[4096];
-
- /*初始化Buf*/
- strcpy(Buf,"Mem is char dev!");
- printf("BUF: %s\n",Buf);
-
- /*打开设备文件*/
- fp0 = fopen("/dev/memdev0","r+");
- if (fp0 == NULL)
- {
- printf("Open Memdev0 Error!\n");
- return -1;
- }
-
- /*写入设备*/
- fwrite(Buf, sizeof(Buf), 1, fp0);
-
- /*重新定位文件位置(思考没有该指令,会有何后果)*/
- fseek(fp0,0,SEEK_SET);
-
- /*清除Buf*/
- strcpy(Buf,"Buf is NULL!");
- printf("BUF: %s\n",Buf);
-
-
- /*读出设备*/
- fread(Buf, sizeof(Buf), 1, fp0);
-
- /*检测结果*/
- printf("BUF: %s\n",Buf);
-
- return 0;
- }
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R0:- char_drv.h
- #ifndef _MEMDEV_H_
- #define _MEMDEV_H_
- #ifndef MEMDEV_MAJOR
- #define MEMDEV_MAJOR 251 /*预设的mem的主设备号*/
- #endif
- #ifndef MEMDEV_NR_DEVS
- #define MEMDEV_NR_DEVS 2 /*设备数*/
- #endif
- #ifndef MEMDEV_SIZE
- #define MEMDEV_SIZE 4096
- #endif
- /*mem设备描述结构体*/
- struct mem_dev
- {
- char *data;
- unsigned long size;
- };
- #endif /* _MEMDEV_H_ */
复制代码 char_drv.c
- #include "char_drv.h"
- #include <linux/module.h>
- #include <linux/types.h>
- #include <linux/fs.h>
- #include <linux/errno.h>
- #include <linux/mm.h>
- #include <linux/sched.h>
- #include <linux/init.h>
- #include <linux/cdev.h>
- #include <asm/io.h>
- #include <asm/system.h>
- #include <asm/uaccess.h>
- static int mem_major = MEMDEV_MAJOR;
- module_param(mem_major, int, S_IRUGO);
- struct mem_dev *mem_devp; /*设备结构体指针*/
- struct cdev cdev;
- /*文件打开函数*/
- int mem_open(struct inode *inode, struct file *filp)
- {
- struct mem_dev *dev;
-
- /*获取次设备号*/
- int num = MINOR(inode->i_rdev);
- if (num >= MEMDEV_NR_DEVS)
- return -ENODEV;
- dev = &mem_devp[num];
-
- /*将设备描述结构指针赋值给文件私有数据指针*/
- filp->private_data = dev;
-
- return 0;
- }
- /*文件释放函数*/
- int mem_release(struct inode *inode, struct file *filp)
- {
- return 0;
- }
- /*读函数*/
- static ssize_t mem_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)
- {
- unsigned long p = *ppos; /*记录文件指针偏移位置*/
- unsigned int count = size; /*记录需要读取的字节数*/
- int ret = 0; /*返回值*/
- struct mem_dev *dev = filp->private_data; /*获得设备结构体指针*/
- /*判断读位置是否有效*/
- if (p >= MEMDEV_SIZE) /*要读取的偏移大于设备的内存空间*/
- return 0;
- if (count > MEMDEV_SIZE - p) /*要读取的字节大于设备的内存空间*/
- count = MEMDEV_SIZE - p;
- /*读数据到用户空间:内核空间->用户空间交换数据*/
- if (copy_to_user(buf, (void*)(dev->data + p), count))
- {
- ret = - EFAULT;
- }
- else
- {
- *ppos += count;
- ret = count;
-
- printk(KERN_INFO "read %d bytes(s) from %ld\n", count, p);
- }
- return ret;
- }
- /*写函数*/
- static ssize_t mem_write(struct file *filp, const char __user *buf, size_t size, loff_t *ppos)
- {
- unsigned long p = *ppos;
- unsigned int count = size;
- int ret = 0;
- struct mem_dev *dev = filp->private_data; /*获得设备结构体指针*/
-
- /*分析和获取有效的写长度*/
- if (p >= MEMDEV_SIZE)
- return 0;
- if (count > MEMDEV_SIZE - p) /*要写入的字节大于设备的内存空间*/
- count = MEMDEV_SIZE - p;
-
- /*从用户空间写入数据*/
- if (copy_from_user(dev->data + p, buf, count))
- ret = - EFAULT;
- else
- {
- *ppos += count; /*增加偏移位置*/
- ret = count; /*返回实际的写入字节数*/
-
- printk(KERN_INFO "written %d bytes(s) from %ld\n", count, p);
- }
- return ret;
- }
- /* seek文件定位函数 */
- static loff_t mem_llseek(struct file *filp, loff_t offset, int whence)
- {
- loff_t newpos;
- switch(whence) {
- case 0: /* SEEK_SET */ /*相对文件开始位置偏移*/
- newpos = offset; /*更新文件指针位置*/
- break;
- case 1: /* SEEK_CUR */
- newpos = filp->f_pos + offset;
- break;
- case 2: /* SEEK_END */
- newpos = MEMDEV_SIZE -1 + offset;
- break;
- default: /* can't happen */
- return -EINVAL;
- }
- if ((newpos<0) || (newpos>MEMDEV_SIZE))
- return -EINVAL;
-
- filp->f_pos = newpos;
- return newpos;
- }
- /*文件操作结构体*/
- static const struct file_operations mem_fops =
- {
- .owner = THIS_MODULE,
- .llseek = mem_llseek,
- .read = mem_read,
- .write = mem_write,
- .open = mem_open,
- .release = mem_release,
- };
- /*设备驱动模块加载函数*/
- static int memdev_init(void)
- {
- int result;
- int i;
- dev_t devno = MKDEV(mem_major, 0);
- /* 申请设备号,当xxx_major不为0时,表示静态指定;当为0时,表示动态申请*/
- /* 静态申请设备号*/
- if (mem_major)
- result = register_chrdev_region(devno, 2, "mem_dev");
- else /* 动态分配设备号 */
- {
- result = alloc_chrdev_region(&devno, 0, 2, "mem_dev");
- mem_major = MAJOR(devno); /*获得申请的主设备号*/
- }
-
- if (result < 0)
- return result;
- /*初始化cdev结构,并传递file_operations结构指针*/
- cdev_init(&cdev, &mem_fops);
- cdev.owner = THIS_MODULE; /*指定所属模块*/
- cdev.ops = &mem_fops;
-
- /* 注册字符设备 */
- cdev_add(&cdev, MKDEV(mem_major, 0), MEMDEV_NR_DEVS);
-
- /* 为设备描述结构分配内存*/
- mem_devp = kmalloc(MEMDEV_NR_DEVS * sizeof(struct mem_dev), GFP_KERNEL);
- if (!mem_devp) /*申请失败*/
- {
- result = - ENOMEM;
- goto fail_malloc;
- }
- memset(mem_devp, 0, sizeof(struct mem_dev));
-
- /*为设备分配内存*/
- for (i=0; i < MEMDEV_NR_DEVS; i++)
- {
- mem_devp[i].size = MEMDEV_SIZE;
- mem_devp[i].data = kmalloc(MEMDEV_SIZE, GFP_KERNEL);
- memset(mem_devp[i].data, 0, MEMDEV_SIZE);
- }
-
- return 0;
- fail_malloc:
- unregister_chrdev_region(devno, 1);
-
- return result;
- }
- /*模块卸载函数*/
- static void memdev_exit(void)
- {
- cdev_del(&cdev); /*注销设备*/
- kfree(mem_devp); /*释放设备结构体内存*/
- unregister_chrdev_region(MKDEV(mem_major, 0), 2); /*释放设备号*/
- }
- MODULE_AUTHOR("djwow");
- MODULE_LICENSE("GPL");
- module_init(memdev_init);
- module_exit(memdev_exit);
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