1.\" Copyright (c) 1998 Jonathan Lemon 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.Dd July 27, 1998 26.Dt I386_VM86 2 27.Os 28.Sh NAME 29.Nm i386_vm86 30.Nd control vm86-related functions 31.Sh LIBRARY 32.Lb libc 33.Sh SYNOPSIS 34.In sys/types.h 35.In machine/sysarch.h 36.In machine/vm86.h 37.Ft int 38.Fn i386_vm86 "int function" "void *data" 39.Sh DESCRIPTION 40The 41.Fn i386_vm86 42system call 43is used to call various vm86 related functions. 44The 45.Fa function 46argument 47can be one of the following values: 48.Bl -tag -offset indent -width VM86_SET_VME 49.It Dv VM86_INIT 50This will initialize the kernel's vm86 parameter area for the 51process, and permit the process to make vm86 calls. 52The 53.Fa data 54argument 55points to the following structure: 56.Bd -literal 57struct vm86_init_args { 58 int debug; 59 int cpu_type; 60 u_char int_map[32]; 61}; 62.Ed 63.Pp 64The 65.Fa debug 66argument 67is used to turn on debugging code. 68The 69.Fa cpu_type 70argument 71controls the type of CPU being emulated, and is currently unimplemented. 72The 73.Fa int_map 74argument 75is a bitmap which determines whether vm86 interrupts should be handled 76in vm86 mode, or reflected back to the process. 77If the 78.Em Nth 79bit is set, the interrupt will be reflected to the process, otherwise 80it will be dispatched by the vm86 interrupt table. 81.It Dv VM86_INTCALL 82This allows calls to be made to vm86 interrupt handlers by the process. 83It effectively simulates an INT instruction. 84.Fa data 85should point to the following structure: 86.Bd -literal 87struct vm86_intcall_args { 88 int intnum; 89 struct vm86frame vmf; 90}; 91.Ed 92.Pp 93.Fa intnum 94specifies the operand of INT for the simulated call. 95A value of 0x10, for example, would often be used to call into the VGA BIOS. 96.Fa vmf 97is used to initialize CPU registers according to the calling convention for 98the interrupt handler. 99.It Dv VM86_GET_VME 100This is used to retrieve the current state of the Pentium(r) processor's 101VME (Virtual-8086 Mode Extensions) flag, which is bit 0 of CR4. 102.Fa data 103should be initialized to point to the following: 104.Bd -literal 105struct vm86_vme_args { 106 int state; /* status */ 107}; 108.Ed 109.Pp 110.Fa state 111will contain the state of the VME flag on return. 112.\" .It Dv VM86_SET_VME 113.El 114.Pp 115vm86 mode is entered by calling 116.Xr sigreturn 2 117with the correct machine context for vm86, and with the 118.Dv PSL_VM 119bit set. 120Control returns to the process upon delivery of a signal. 121.Sh RETURN VALUES 122.Rv -std i386_vm86 123.Sh ERRORS 124The 125.Fn i386_vm86 126system call 127will fail if: 128.Bl -tag -width Er 129.It Bq Er EINVAL 130The kernel does not have vm86 support, or an invalid function was specified. 131.It Bq Er ENOMEM 132There is not enough memory to initialize the kernel data structures. 133.El 134.Sh AUTHORS 135.An -nosplit 136This man page was written by 137.An Jonathan Lemon , 138and updated by 139.An Bruce M Simpson . 140