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 and 1.1.9.
These calls cause the process to enter VM86 mode, and are
used by dosemu.
On success, zero is returned. On error, -1 is returned,
and errno is set appropriately.
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.