Linux设备驱动remap_pfn_range() 和remap_page_range()

LDD3的开发环境推荐的是2.6.10，安装了RHEL4-update4，其内核版本为2.6.9.42，编译mmap的程序时报错：Unknown symbol remap_pfn_range

在网上查了下，应将上述报错的函数改为remap_page_range，并且remap_page_range不再推荐使用了，两个内核函数第二个参数定义不相同：

int remap_page_range(struct vm_area_struct *vma,
            unsigned long from, 
            unsigned long phys_addr, //
            unsigned long size, 
            pgprot_t prot)
			

int remap_pfn_range(struct vm_area_struct *vma,
            unsigned long addr,
            unsigned long pfn,		//注意和上述的不同
            unsigned long size,
            pgprot_t prot)	

直接看下面的一段程序，在注释中已经将两个函数的使用区分出来了。使用前，先mknod /dev/mymap c 60 0

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
//#include 


#define DEVICE_NAME "mymap"


static unsigned char array[10]={0,1,2,3,4,5,6,7,8,9};
static unsigned char *buffer;


static int my_open(struct inode *inode, struct file *file)
{
    return 0;
}


static int my_map(struct file *filp, struct vm_area_struct *vma)
{    
    unsigned long page;
    unsigned char i;
    unsigned long start = (unsigned long)vma->vm_start;
    //unsigned long end =  (unsigned long)vma->vm_end;
    unsigned long size = (unsigned long)(vma->vm_end - vma->vm_start);

    //得到物理地址
    page = virt_to_phys(buffer);    
    //将用户空间的一个vma虚拟内存区映射到以page开始的一段连续物理页面上
    //if(remap_pfn_range(vma,start,page>>PAGE_SHIFT,size,PAGE_SHARED))//第三个参数是页帧号，由物理地址右移PAGE_SHIFT得到
	if(remap_page_range(vma,start,page,size,PAGE_SHARED))//第三个参数是页帧号，由物理地址右移PAGE_SHIFT得到	
        return -1;

    //往该内存写10字节数据
    for(i=0;i<10;i++)
        buffer[i] = array[i];
    
    return 0;
}


static struct file_operations dev_fops = {
    .owner    = THIS_MODULE,
    .open    = my_open,
    .mmap   = my_map,
};

/*
static struct miscdevice misc = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = DEVICE_NAME,
    .fops = &dev_fops,
};
*/

static int __init dev_init(void)
{
    int ret;    

    //注册混杂设备
    //ret = misc_register(&misc);
	
	
	ret = register_chrdev(60, DEVICE_NAME, &dev_fops);
    if (ret < 0) 
	{
            printk("<1> memory: can't obtain major number %d\n", 60);
            return ret;
    }

	
    //内存分配
    buffer = (unsigned char *)kmalloc(PAGE_SIZE,GFP_KERNEL);
    //将该段内存设置为保留
    SetPageReserved(virt_to_page(buffer));

    return ret;
}


static void __exit dev_exit(void)
{
    //注销设备
    //misc_deregister(&misc);
	 unregister_chrdev(60, DEVICE_NAME);
	 
	 
    //清除保留
    ClearPageReserved(virt_to_page(buffer));
    //释放内存
    kfree(buffer);
}


module_init(dev_init);
module_exit(dev_exit);
MODULE_LICENSE("Dual BSD/GPL");

应用程序：

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include  

#define PAGE_SIZE 4096


int main(int argc , char *argv[])
{
    int fd;
    int i;
    unsigned char *p_map;
    
    //打开设备
    fd = open("/dev/mymap",O_RDWR);
    if(fd < 0)
    {
        printf("open fail\n");
        exit(1);
    }

    //内存映射
    p_map = (unsigned char *)mmap(0, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,fd, 0);
    if(p_map == MAP_FAILED)
    {
        printf("mmap fail\n");
        goto here;
    }

    //打印映射后的内存中的前10个字节内容
    for(i=0;i<10;i++)
        printf("%d\n",p_map[i]);
    

here:
    munmap(p_map, PAGE_SIZE);
    return 0;
}

makefile文件：

obj-m := testdrv.o
PWD       := $(shell pwd)
all:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
	rm -rf *.o *~ core .*.cmd *.mod.c ./tmp_version