gnu_dev_major

MAKEDEV(3)                 Linux Programmer's Manual                MAKEDEV(3)

NAME
       makedev, major, minor - manage a device number

SYNOPSIS
       #include <sys/sysmacros.h>

       dev_t makedev(unsigned int maj, unsigned int min);

       unsigned int major(dev_t dev);
       unsigned int minor(dev_t dev);

DESCRIPTION
       A device ID consists of two parts: a major ID, identifying the class of
       the device, and a minor ID, identifying a specific instance of a device
       in that class.  A device ID is represented using the type dev_t.

       Given major and minor device IDs, makedev() combines these to produce a
       device ID, returned as the function result.   This  device  ID  can  be
       given to mknod(2), for example.

       The  major()  and  minor() functions perform the converse task: given a
       device ID, they return, respectively, the major and  minor  components.
       These macros can be useful to, for example, decompose the device IDs in
       the structure returned by stat(2).

ATTRIBUTES
       For  an  explanation  of  the  terms  used   in   this   section,   see
       attributes(7).

       +----------------------------+---------------+---------+
       |Interface                   | Attribute     | Value   |
       +----------------------------+---------------+---------+
       |makedev(), major(), minor() | Thread safety | MT-Safe |
       +----------------------------+---------------+---------+
CONFORMING TO
       The  makedev(),  major(),  and  minor()  functions are not specified in
       POSIX.1, but are present on many other systems.

NOTES
       These interfaces are defined as macros.  Since glibc 2.3.3,  they  have
       been  aliases  for  three  GNU-specific  functions:  gnu_dev_makedev(),
       gnu_dev_major(), and gnu_dev_minor().  The latter names  are  exported,
       but the traditional names are more portable.

       The  BSDs  expose  the  definitions for these macros via <sys/types.h>.
       glibc also exposes definitions for these macros from that  header  file
       if  suitable  feature  test  macros are defined, but this is deprecated
       since glibc 2.25 and will be removed in the future.

SEE ALSO
       mknod(2), stat(2)

COLOPHON
       This page is part of release 4.15 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       https://www.kernel.org/doc/man-pages/.

Linux                             2017-09-15                        MAKEDEV(3)
Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2021 Hurricane Electric. All Rights Reserved.