AMD64_GET_IOPERM(2) OpenBSD Programmer's Manual (AMD64) AMD64_GET_IOPERM(2)NAME
amd64_get_ioperm, amd64_set_ioperm - manage amd64 per-process I/O
DESCRIPTIONamd64_get_ioperm() copies the current I/O permission bitmap into the
memory referenced by iomap.
amd64_set_ioperm() sets the I/O permission bitmap from the data pointed
to by iomap. This call is restricted to the superuser.
The permission bitmap contains 1024 bits in 32 longwords. If bit n is
clear in the bitmap, then access is granted to I/O port n. If bit n is
set in the bitmap, then an attempt to access I/O port n results in
delivery of a SIGBUS signal unless the process's I/O permission level
would grant I/O access.
Note: Code using the amd64_get_ioperm() and amd64_set_ioperm() functions
must be compiled using -lamd64.
Upon successful completion, amd64_get_ioperm() and amd64_set_ioperm()
return 0. Otherwise, a value of -1 is returned and the global variable
errno is set to indicate the error.
ERRORSamd64_get_ioperm() and amd64_set_ioperm() will fail if:
[EFAULT] iomap points outside the process's allocated address space.
[EPERM] The caller was not the superuser.
Intel, AMD64 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.
The bitmap should really cover 65536 bits, but that's just too big for
allocation in a kernel structure. If you need access to ports beyond
1024, use amd64_iopl(2).
OpenBSD 4.9 June 26, 2008 OpenBSD 4.9