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       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

       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.


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