I386_IOPL(2) | System Calls Manual (i386) | I386_IOPL(2)

# 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.

April 12, 2004 | NetBSD 9.3