io(4) - NetBSD Manual Pages

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IO(4)                NetBSD/i386 Kernel Interfaces Manual                IO(4)


NAME

     io -- I/O privilege file


DESCRIPTION

     This device is obsolete and is provided for compatibility purposes only;
     use i386_iopl(2) instead.

     After opening /dev/io for writing the process is granted full I/O privi-
     leges; closing the returned file descriptor does not result in revocation
     of these privileges.  The new I/O privileges can be useful in order to
     write userland programs that handle some hardware directly.

     The entire access control is handled by the file access permissions of
     /dev/io, so care should be taken in granting rights for this device.

     I/O privilege on access to /dev/io is only granted if the kernel was
     built with the COMPAT_10 option.


FILES

     /dev/io


SEE ALSO

     mem(4)


HISTORY

     The io file appeared in NetBSD 1.0 after it was in the kernel for some
     time.

NetBSD 5.2.3                    January 1, 1996                   NetBSD 5.2.3