IO(4) | Device Drivers Manual (i386) | 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This device is obsolete and is provided for compatibility purposes only; use i386_iopl(2) instead.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.

January 1, 1996 | NetBSD 9.4