1VM86(2)                    Linux Programmer's Manual                   VM86(2)
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NAME

6       vm86old, vm86 - enter virtual 8086 mode
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SYNOPSIS

9       #include <sys/vm86.h>
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11       int vm86old(struct vm86_struct *info);
12       int vm86(unsigned long fn, struct vm86plus_struct *v86);
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DESCRIPTION

15       The system call vm86() was introduced in Linux 0.97p2.  In Linux 2.1.15
16       and 2.0.28, it was renamed to vm86old(), and a new  vm86()  was  intro‐
17       duced.   The  definition of struct vm86_struct was changed in 1.1.8 and
18       1.1.9.
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20       These calls cause the process to enter VM86 mode (virtual-8086 in Intel
21       literature), and are used by dosemu.
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23       VM86 mode is an emulation of real mode within a protected mode task.
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RETURN VALUE

26       On  success,  zero is returned.  On error, -1 is returned, and errno is
27       set to indicate the error.
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ERRORS

30       EFAULT This return value is specific to i386 and  indicates  a  problem
31              with getting user-space data.
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33       ENOSYS This  return  value indicates the call is not implemented on the
34              present architecture.
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36       EPERM  Saved kernel stack exists.  (This is a kernel sanity check;  the
37              saved stack should exist only within vm86 mode itself.)
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CONFORMING TO

40       This  call  is specific to Linux on 32-bit Intel processors, and should
41       not be used in programs intended to be portable.
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COLOPHON

44       This page is part of release 5.13 of the Linux  man-pages  project.   A
45       description  of  the project, information about reporting bugs, and the
46       latest    version    of    this    page,    can     be     found     at
47       https://www.kernel.org/doc/man-pages/.
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51Linux                             2021-03-22                           VM86(2)
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