vm86(2) -- Linux man page
NAMEvm86old, vm86 - enter virtual 8086 mode
int vm86old(struct vm86_struct *info);
DESCRIPTIONThe 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.
RETURN VALUEOn success, zero is returned. On error, -1 is returned, and errno is set appropriately.
- Saved kernel stack exists. (This is a kernel sanity check; the saved stack should only exist within vm86 mode itself.)
- This return value is specific to i386 and indicates a problem with getting userspace data.
- This return value indicates the call is not implemented on the present architecture.
CONFORMING TOThis call is specific to Linux on Intel processors, and should not be used in programs intended to be portable.