vring->size = sz;
vring->call_fd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
vring->kick_fd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
vring->size = sz;
vring->call_fd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
vring->kick_fd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);