I386_GET_IOPERM(2) BSD Programmer's Manual (i386) I386_GET_IOPERM(2)
i386_get_ioperm, i386_set_ioperm - manage i386 per-process I/O permission bitmap
#include <sys/types.h> #include <machine/sysarch.h> int i386_get_ioperm(u_long *iomap); int i386_set_ioperm(u_long *iomap);
i386_get_ioperm() copies the current I/O permission bitmap into the memory referenced by iomap. i386_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 i386_get_ioperm() and i386_set_ioperm() functions must be compiled using -li386.
Upon successful completion, i386_get_ioperm() and i386_set_ioperm() re- turn 0. Otherwise, a value of -1 is returned and the global variable errno is set to indicate the error.
i386_get_ioperm() and i386_set_ioperm() will fail if: [EFAULT] iomap points outside the process's allocated address space. [EPERM] The caller was not the superuser.
i386_iopl(2) 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.
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 i386_iopl(2). MirOS BSD #10-current October 14, 1995 1
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