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



NAME
       vm86old, vm86 - enter virtual 8086 mode

SYNOPSIS
       #include <sys/vm86.h>

       int vm86old(struct vm86_struct *info);

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

DESCRIPTION
       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.

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

ERRORS
       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 architec‐
              ture.

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

CONFORMING TO
       This  call is specific to Linux on 32-bit Intel processors, and should not be used in pro‐
       grams intended to be portable.

COLOPHON
       This page is part of release 3.74 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 http://www.kernel.org/doc/man-pages/.



Linux                                       2009-02-20                                    VM86(2)