NAME
i386_iopl —
change the i386 I/O
privilege level
LIBRARY
i386 Architecture Library (libi386, -li386)
SYNOPSIS
#include <sys/types.h>
#include <machine/sysarch.h>
int
i386_iopl(
int
iopl);
DESCRIPTION
i386_iopl() sets the i386 I/O privilege level to the value
specified by
iopl. This call is restricted to the
super-user.
RETURN VALUES
Upon successful completion,
i386_iopl() returns 0. Otherwise,
a value of -1 is returned and the global variable
errno
is set to indicate the error.
ERRORS
i386_iopl() will fail if:
-
-
- [
EPERM
]
- The caller was not the super-user, or the operation was not
permitted at the current security level.
REFERENCES
i386 Microprocessor Programmer's Reference Manual, Intel
WARNING
You can really hose your machine if you enable user-level I/O and write to
hardware ports without care.