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


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 intro- duced. 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 userspace 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 only exist within vm86 mode itself.)


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)

1994 Man-cgi 1.15, Panagiotis Christias <>