device number(dev_t)

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本文介绍Linux系统中dev_t类型及其作用于设备号管理的方法。包括如何使用构造函数MKDEV来创建设备号，通过MAJOR和MINOR宏获取设备号的主要和次要部分，以及如何利用register_chrdev_region、alloc_chrdev_region和unregister_chrdev_region等函数注册和释放设备号。

dev_t

description:
the dev_t type in is used to hold device numbers—both the major and minor

parts.

header:
#include

constructor:
MKDEV(int major, int minor);

method:
    MAJOR(dev_t dev);    //obtain the major part of a dev_t
    MINOR(dev_t dev);    //obtain the minor part of a dev_t
    register_chrdev_region();    //manually obtain(register) device numbers

from the system
alloc_chrdev_region(); //allocate a major number by kernel
unregister_chrdev_region(); //free the device number back to kernel

int print_dev_t(char *buffer, dev_t dev); //encode the device number into the given buffer; 
char *format_dev_t(char *buffer, dev_t dev); //encode the device number into the given buffer;