vm86_intcall
if (vm86_intcall(0x15, &vmf) == 0) {
vm86_intcall(0x15, &vmf);
vm86_intcall(0x12, &vmf);
if ((error = vm86_intcall(sa.intnum, &sa.vmf)))
extern int vm86_intcall(int, struct vm86frame *);
vm86_intcall(0x15, &vmf);