1.\" $OpenBSD: i386_get_fsbase.2,v 1.1 2011/03/12 04:12:29 guenther Exp $ 2.\" $NetBSD: i386_get_ioperm.2,v 1.3 1996/02/27 22:57:17 jtc Exp $ 3.\" 4.\" Copyright (c) 1996 The NetBSD Foundation, Inc. 5.\" All rights reserved. 6.\" 7.\" This code is derived from software contributed to The NetBSD Foundation 8.\" by John T. Kohl and Charles M. Hannum. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE 23.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29.\" POSSIBILITY OF SUCH DAMAGE. 30.\" 31.Dd $Mdocdate: March 12 2011 $ 32.Dt I386_GET_FSBASE 2 i386 33.Os 34.Sh NAME 35.Nm i386_get_fsbase , 36.Nm i386_set_fsbase 37.Nd manage i386 per-thread %fs base address 38.Sh SYNOPSIS 39.Fd #include <sys/types.h> 40.Fd #include <machine/sysarch.h> 41.Ft int 42.Fn i386_get_fsbase "void **base" 43.Ft int 44.Fn i386_set_fsbase "void *base" 45.Sh DESCRIPTION 46.Fn i386_get_fsbase 47copies the current base address of the segment that, by default, 48is referenced by the %fs selector into the memory referenced by 49.Fa base . 50.Pp 51.Fn i386_set_fsbase 52sets the base address of the segment that, by default, is referenced 53by %fs to the address 54.Fa base . 55.Pp 56When rfork(RFPROC | RFTHREAD) is used, the segment base address 57for the above calls is a per-thread value. 58When a new thread is created, 59it inherits the base from the thread that created it. 60.Pp 61.Sy Note: 62Code using the 63.Fn i386_get_fsbase 64and 65.Fn i386_set_fsbase 66functions must be compiled using 67.Cm -li386 . 68.Sh RETURN VALUES 69Upon successful completion, 70.Fn i386_get_fsbase 71and 72.Fn i386_set_fsbase 73return 0. 74Otherwise, a value of \-1 is returned and the global variable 75.Va errno 76is set to indicate the error. 77.Sh ERRORS 78.Fn i386_get_fsbase 79will fail if: 80.Bl -tag -width [EINVAL] 81.It Bq Er EFAULT 82.Fa base 83points outside the process's allocated address space. 84.El 85.Sh SEE ALSO 86.Rs 87.%A Intel 88.%T i386 Microprocessor Programmer's Reference Manual 89.Re 90