MirOS Manual: i386_get_ioperm(2), i386_set_ioperm(2)

I386_GET_IOPERM(2)      BSD Programmer's Manual (i386)      I386_GET_IOPERM(2)

NAME

     i386_get_ioperm, i386_set_ioperm - manage i386 per-process I/O permission
     bitmap

SYNOPSIS

     #include <sys/types.h>
     #include <machine/sysarch.h>

     int
     i386_get_ioperm(u_long *iomap);

     int
     i386_set_ioperm(u_long *iomap);

DESCRIPTION

     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.

RETURN VALUES

     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.

ERRORS

     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.

SEE ALSO

     i386_iopl(2)

     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.

BUGS

     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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