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make_dev, make_dev_alias, destroy_dev, dev_depends - manage cdev’s and



      make_dev, make_dev_alias, destroy_dev, dev_depends - manage cdev’s and
      DEVFS registration for devices


      #include <sys/param.h>
      #include <sys/conf.h>
      struct cdev *
      make_dev(struct cdevsw *cdevsw, int minor, uid_t uid, gid_t gid,
              int perms, const char *fmt, ...);
      struct cdev *
      make_dev_alias(struct cdev *pdev, const char *fmt, ...);
      destroy_dev(struct cdev *dev);
      dev_depends(struct cdev *pdev, struct cdev *cdev);


      The make_dev() function creates a cdev structure for a new device.  If
      DEVFS is available, it is also notified of the presence of the new
      device.  The device will be owned by uid, with the group ownership as
      gid.  The name is the expansion of fmt and following arguments as
      printf(9) would print it.  The name determines its path under /dev or
      other devfs(5) mount point and may contain slash ‘/’ characters to denote
      subdirectories.  The permissions of the file specified in perms are
      defined in
            #define S_IRWXU 0000700    /* RWX mask for owner */
            #define S_IRUSR 0000400    /* R for owner */
            #define S_IWUSR 0000200    /* W for owner */
            #define S_IXUSR 0000100    /* X for owner */
            #define S_IRWXG 0000070    /* RWX mask for group */
            #define S_IRGRP 0000040    /* R for group */
            #define S_IWGRP 0000020    /* W for group */
            #define S_IXGRP 0000010    /* X for group */
            #define S_IRWXO 0000007    /* RWX mask for other */
            #define S_IROTH 0000004    /* R for other */
            #define S_IWOTH 0000002    /* W for other */
            #define S_IXOTH 0000001    /* X for other */
            #define S_ISUID 0004000    /* set user id on execution */
            #define S_ISGID 0002000    /* set group id on execution */
            #define S_ISVTX 0001000    /* sticky bit */
            #ifndef _POSIX_SOURCE
            #define S_ISTXT 0001000
      The make_dev_alias() function takes the returned cdev from make_dev() and
      makes another (aliased) name for this device.  It is an error to call
      make_dev_alias() prior to calling make_dev().
      The cdev returned by make_dev() and make_dev_alias() has two fields,
      si_drv1 and si_drv2, that are available to store state.  Both fields are
      of type void *.  These are designed to replace the minor argument to
      The destroy_dev() function takes the returned cdev from make_dev() and
      destroys the registration for that device.  Do not call destroy_dev() on
      devices that were created with make_dev_alias().
      The dev_depends() function establishes a parent-child relationship
      between two devices.  The net effect is that a destroy_dev() of the par‐
      ent device will also result in the destruction of the child device(s), if
      any exist.  A device may simultaneously be a parent and a child, so it is
      possible to build a complete hierarchy.


      The make_dev() and destroy_dev() functions first appeared in FreeBSD 4.0.
      The function make_dev_alias() first appeared in FreeBSD 4.1.  The func‐
      tion dev_depends() first appeared in FreeBSD 5.0.


Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.