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

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

       ENOSYS This return value indicates the call is not implemented on  the  present  architec-
              ture.

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



Linux 2.1.15                                1997-07-17                                    VM86(2)