nv_exists
bool nv_exists(struct nv *nv, const char *namefmt, ...) __printflike(2, 3);
memsyncack = nv_exists(nv, "received");
if (nv_exists(nvin, "wait"))
if (nv_exists(nvin, "virgin")) {
if (nv_exists(nvin, "virgin")) {
hio->hio_memsync = nv_exists(nv, "memsync");