This device is obsolete and is provided for compatibility purposes only; use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.