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This device is obsolete and is provided for compatibility purposes only; use i386_iopl(2) instead.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