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MAKEDEV(3)		 BSD 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 returns a device number created from the provided
     major and minor number.  The major() and minor() macros return the	origi-
     nal numbers from the device number	dev.  In other words, for a value dev
     of	the type dev_t,	and values ma, mi of the type int, the assertions
	   dev == makedev(major(dev), minor(dev))
	   ma == major(makedev(ma, mi))
	   mi == minor(makedev(ma, mi))
     are valid.

     In	previous implementations of FreeBSD all	block and character devices
     were uniquely identified by a pair	of stable major	and minor numbers.
     The major number referred to a certain device class (e.g. disks, TTYs)
     while the minor number identified an instance within the device class.
     Later versions of FreeBSD automatically generate a	unique device number
     for each character	device visible in /dev/.  These	numbers	are not	di-
     vided in device classes and are not guaranteed to be stable upon reboot
     or	driver reload.

     On	FreeBSD	these macros are only used by utilities	that need to exchange
     numbers with other	operating systems that may use different encodings for
     dev_t, but	also applications that present these numbers to	the user in a
     more conventional way.

RETURN VALUES
     The major() and minor() macros return numbers whose value can span	the
     complete range of an int.

SEE ALSO
     mknod(2), devname(3), devfs(5)

BSD				August 3, 2017				   BSD

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO

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