1vm86(2)                       System Calls Manual                      vm86(2)
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NAME

6       vm86old, vm86 - enter virtual 8086 mode
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LIBRARY

9       Standard C library (libc, -lc)
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SYNOPSIS

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

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

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

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

43       Linux on 32-bit Intel processors.
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47Linux man-pages 6.04              2023-03-30                           vm86(2)