NAME    [Toc]    [Back]

     amd64_iopl - change the amd64 I/O privilege level

SYNOPSIS    [Toc]    [Back]

     #include <sys/types.h>
     #include <machine/sysarch.h>

     int
     amd64_iopl(int iopl);

DESCRIPTION    [Toc]    [Back]

     amd64_iopl() sets the amd64 I/O privilege level to the value
specified by
     iopl.  This call is restricted to the superuser.

     Note:  Code using the amd64_iopl() function must be compiled
using
     -lamd64.

RETURN VALUES    [Toc]    [Back]

     Upon successful completion, amd64_iopl() returns 0.   Otherwise, a value
     of  -1  is  returned and the global variable errno is set to
indicate the
     error.

ERRORS    [Toc]    [Back]

     amd64_iopl() will fail if:

     [EPERM]   The caller was not the superuser.

SEE ALSO    [Toc]    [Back]

     amd64_get_ioperm(2), amd64_set_ioperm(2)

REFERENCES    [Toc]    [Back]

     Intel, AMD64 Microprocessor Programmer's Reference Manual.

WARNING    [Toc]    [Back]

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

OpenBSD      3.6                         October     14,     1995