142 lines
4.0 KiB
Groff
142 lines
4.0 KiB
Groff
.\" Copyright (c) 1998 Jonathan Lemon
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 27, 1998
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.Os
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.Dt I386_VM86 2
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.Sh NAME
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.Nm i386_vm86
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.Nd control vm86-related functions
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/types.h
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.In machine/sysarch.h
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.In machine/vm86.h
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.Ft int
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.Fn i386_vm86 "int function" "void *data"
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.Sh DESCRIPTION
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The
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.Fn i386_vm86
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system call
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is used to call various vm86 related functions.
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The
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.Fa function
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argument
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can be one of the following values:
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.Bl -tag -offset indent -width VM86_SET_VME
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.It Dv VM86_INIT
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This will initialize the kernel's vm86 parameter area for the
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process, and permit the process to make vm86 calls.
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The
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.Fa data
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argument
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points to the following structure:
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.Bd -literal
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struct vm86_init_args {
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int debug;
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int cpu_type;
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u_char int_map[32];
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};
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.Ed
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.Pp
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The
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.Fa debug
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argument
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is used to turn on debugging code.
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The
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.Fa cpu_type
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argument
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controls the type of CPU being emulated, and is currently unimplemented.
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The
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.Fa int_map
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argument
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is a bitmap which determines whether vm86 interrupts should be handled
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in vm86 mode, or reflected back to the process.
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If the
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.Em Nth
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bit is set, the interrupt will be reflected to the process, otherwise
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it will be dispatched by the vm86 interrupt table.
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.It Dv VM86_INTCALL
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This allows calls to be made to vm86 interrupt handlers by the process.
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It effectively simulates an INT instruction.
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.Fa data
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should point to the following structure:
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.Bd -literal
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struct vm86_intcall_args {
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int intnum;
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struct vm86frame vmf;
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};
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.Ed
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.Pp
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.Fa intnum
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specifies the operand of INT for the simulated call.
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A value of 0x10, for example, would often be used to call into the VGA BIOS.
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.Fa vmf
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is used to initialize CPU registers according to the calling convention for
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the interrupt handler.
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.It Dv VM86_GET_VME
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This is used to retrieve the current state of the Pentium(r) processor's
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VME (Virtual-8086 Mode Extensions) flag, which is bit 0 of CR4.
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.Fa data
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should be initialized to point to the following:
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.Bd -literal
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struct vm86_vme_args {
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int state; /* status */
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};
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.Ed
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.Pp
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.Fa state
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will contain the state of the VME flag on return.
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.\" .It Dv VM86_SET_VME
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.El
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.Pp
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vm86 mode is entered by calling
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.Xr sigreturn 2
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with the correct machine context for vm86, and with the
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.Dv PSL_VM
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bit set.
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Control returns to the process upon delivery of a signal.
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.Sh RETURN VALUES
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.Rv -std i386_vm86
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.Sh ERRORS
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The
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.Fn i386_vm86
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system call
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The kernel does not have vm86 support, or an invalid function was specified.
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.It Bq Er ENOMEM
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There is not enough memory to initialize the kernel data structures.
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.El
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.Sh AUTHORS
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.An -nosplit
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This man page was written by
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.An Jonathan Lemon ,
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and updated by
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.An Bruce M Simpson .
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