device number(dev_t)

 2009-08-21 10:08:03 阅读26 评论0 字号：大中小

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;

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