vm86old, vm86 - enter virtual 8086 mode
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
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
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
EPERM Saved kernel stack exists. (This is a kernel sanity check; the
saved stack should only exist 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 3.24 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.