vm86old, vm86 - enter virtual 8086 mode


   #include <sys/vm86.h>

   int vm86old(struct vm86_struct *info);

   int vm86(unsigned long fn, struct vm86plus_struct *v86);


   The system call vm86() was introduced in Linux 0.97p2.  In Linux 2.1.15
   and 2.0.28,  it  was  renamed  to  vm86old(),  and  a  new  vm86()  was
   introduced.   The definition of struct vm86_struct was changed in 1.1.8
   and 1.1.9.

   These calls cause the process to enter VM86 mode (virtual-8086 in Intel
   literature), and are used by dosemu.

   VM86 mode is an emulation of real mode within a protected mode task.


   On  success,  zero is returned.  On error, -1 is returned, and errno is
   set appropriately.


   EFAULT This return value is specific to i386 and  indicates  a  problem
          with getting user-space data.

   ENOSYS This  return  value indicates the call is not implemented on the
          present architecture.

   EPERM  Saved kernel stack exists.  (This is a kernel sanity check;  the
          saved stack should exist only within vm86 mode itself.)


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


   This page is part of release 4.09 of the Linux  man-pages  project.   A
   description  of  the project, information about reporting bugs, and the
   latest    version    of    this    page,    can     be     found     at


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