|I386_IOPL(2)||System Calls Manual (i386)||I386_IOPL(2)|
i386_iopl — change
the i386 I/O privilege level
sets the i386 I/O privilege level to the value specified by
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.
Upon successful completion,
returns 0. Otherwise, a value of -1 is returned and the global variable
errno is set to indicate the error.
i386_iopl() will fail if:
Intel, i386 Microprocessor Programmer's Reference Manual.
You can really hose your machine if you enable user-level I/O and write to hardware ports without care.
|March 24, 2016||OpenBSD-6.1|