i386_iopl man page on OpenBSD

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I386_IOPL(2)	      OpenBSD Programmer's Manual (i386)	  I386_IOPL(2)

NAME
     i386_iopl - change the i386 I/O privilege level

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 may only be made by the superuser.  Additionally, it is only
     permitted when the securelevel(7) is less than or equal to 0 or the
     machdep.allowaperture sysctl has been set to a non-zero value.

     Note: Code using the i386_iopl() function must be compiled using -li386.

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 superuser, or the securelevel is greater
	       than zero and machdep.allowaperture has not been set to a non-
	       zero value.

SEE ALSO
     i386_get_ioperm(2), i386_set_ioperm(2), securelevel(7)

REFERENCES
     Intel, i386 Microprocessor Programmer's Reference Manual.

WARNING
     You can really hose your machine if you enable user-level I/O and write
     to hardware ports without care.

OpenBSD 4.9			 June 26, 2008			   OpenBSD 4.9
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