mirror of https://github.com/mkerrisk/man-pages
77 lines
2.5 KiB
Groff
77 lines
2.5 KiB
Groff
.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
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.\" Copyright 1997 Andries E. Brouwer (aeb@cwi.nl)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH VM86 2 2021-03-22 "Linux" "Linux Programmer's Manual"
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.SH NAME
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vm86old, vm86 \- enter virtual 8086 mode
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.SH SYNOPSIS
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.nf
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.B #include <sys/vm86.h>
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.PP
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.BI "int vm86old(struct vm86_struct *" info );
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.BI "int vm86(unsigned long " fn ", struct vm86plus_struct *" v86 );
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.fi
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.SH DESCRIPTION
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The system call
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.BR vm86 ()
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was introduced in Linux 0.97p2.
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In Linux 2.1.15 and 2.0.28, it was renamed to
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.BR vm86old (),
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and a new
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.BR vm86 ()
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was introduced.
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The definition of
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.IR "struct vm86_struct"
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was changed
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in 1.1.8 and 1.1.9.
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.PP
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These calls cause the process to enter VM86 mode (virtual-8086 in Intel
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literature), and are used by
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.BR dosemu .
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.PP
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VM86 mode is an emulation of real mode within a protected mode task.
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.SH RETURN VALUE
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On success, zero is returned.
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On error, \-1 is returned, and
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.I errno
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is set to indicate the error.
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.SH ERRORS
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.TP
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.B EFAULT
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This return value is specific to i386 and indicates a problem with getting
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user-space data.
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.TP
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.B ENOSYS
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This return value indicates the call is not implemented on the present
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architecture.
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.TP
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.B EPERM
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Saved kernel stack exists.
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(This is a kernel sanity check; the saved
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stack should exist only within vm86 mode itself.)
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.SH CONFORMING TO
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This call is specific to Linux on 32-bit Intel processors,
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and should not be used in programs intended to be portable.
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