ucontext_alloc
extern ucontext_t *ucontext_alloc(uint32_t);
ucontext_t *ctx = ucontext_alloc(0);
ctx = ucontext_alloc(0);
ctx = ucontext_alloc(0);
mk_ctx = ucontext_alloc(0);
orig_ctx = ucontext_alloc(0);
ucontext_t *ctx = ucontext_alloc(0);
xsave_buf = ucontext_alloc(0);