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MAKEDEV(3)              NetBSD Library Functions Manual             MAKEDEV(3)


NAME

     makedev, major, minor -- device number conversion


SYNOPSIS

     #include <sys/types.h>

     dev_t
     makedev(int major, int minor);

     int
     major(dev_t dev);

     int
     minor(dev_t dev);


DESCRIPTION

     The makedev() macro allows a unique device number to be generated based
     on its major and minor number.  The major() and minor() macros can be
     used to obtain the original numbers from the device number dev.

     All block and character devices are uniquely identified by a pair of
     major and minor numbers.  The major number refers to a certain device
     class (e.g. disks, TTYs) while the minor number identifies an instance
     within the device class.


RETURN VALUES

     The major() macro returns a device major number that has a value between
     0 and 4095 (0xfff).  The minor() macro returns a device minor number that
     has a value between 0 and 1048575 (0xfffff).


SEE ALSO

     mknod(2), devname(3), MAKEDEV(8)


HISTORY

     The major and minor numbers used to support values between 0 and 255
     (0xff) until NetBSD 1.3 when the macros were changed to support their
     current ranges.

NetBSD 11.99                     April 9, 2026                    NetBSD 11.99