i386_iopl(2) - NetBSD Manual Pages

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I386_IOPL(2)            NetBSD/i386 System Calls Manual           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.

NetBSD 7.1.2                    April 12, 2004                    NetBSD 7.1.2