NetBSD/lib/libarch/i386/i386_get_ioperm.2

.\"	$NetBSD: i386_get_ioperm.2,v 1.4 1997/04/26 21:31:09 tls Exp $
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.Dd October 14, 1995
.Dt I386_GET_IOPERM 2
.Os NetBSD
.Sh NAME
.Nm i386_get_ioperm ,
.Nm i386_set_ioperm
.Nd manage i386 per-process I/O permission bitmap
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <machine/sysarch.h>
.Ft int
.Fn i386_get_ioperm "u_long *iomap"
.Ft int
.Fn i386_set_ioperm "u_long *iomap"
.Sh DESCRIPTION
.Fn i386_get_ioperm
copies the current I/O permission bitmap into the memory referenced by
.Ar iomap .
.Pp
.Fn i386_set_ioperm
sets the I/O permission bitmap from the data pointed to by
.Ar iomap .
This call is restricted to the super-user.
.Pp
The permission bitmap contains 
1024
bits in 32 longwords.
If bit
.Va n
is clear in the bitmap, then access is granted to I/O port
.Va n .
If bit
.Va n
is set in the bitmap, then an attempt to access I/O port
.Va n
results in delivery of a SIGBUS signal unless the process's I/O
permission level would grant I/O access.
.Sh RETURN VALUES
Upon successful completion,
.Fn i386_get_ioperm
and
.Fn i386_set_ioperm
return 0.
Otherwise, a value of -1 is returned and the global
variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn i386_get_ioperm
and
.Fn i386_set_ioperm
will fail if:
.Bl -tag -width [EINVAL]
.It Bq Er EFAULT
.Ar Iomap
points outside the process's allocated address space.
.It Bq Er EPERM
The caller was not the super-user, or the operation was not permitted at the current security level.
.El
.Sh 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
.Xr i386_iopl 2 .
.Sh SEE ALSO
.Xr i386_iopl 2 
.Sh REFERENCES
i386 Microprocessor Programmer's Reference Manual, Intel
.Sh WARNING
You can really hose your machine if you enable user-level I/O and
write to hardware ports without care.