MirBSD manpage: i386_iopl(2)

I386_IOPL(2)            BSD 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 is restricted to the superuser.

     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 er-
     ror.

ERRORS

     i386_iopl() will fail if:

     [EPERM]   The caller was not the superuser.

SEE ALSO

     i386_get_ioperm(2), i386_set_ioperm(2)

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.

MirBSD #10-current             October 14, 1995                              1