newnv
struct nvlist *newnv(const char *, const char *, void *, int, struct nvlist *);
nv = newnv(name, NULL, NULL, dev->d_umax, NULL);
nv = newnv(name, NULL, NULL, sel, NULL);
#define new0(n,s,p,i,x) (alloc[adepth++] = newnv(n, s, p, i, x))
nv = newnv(name, value, NULL, 0, NULL);
n = newnv(NULL, NULL, dev, 0, l);
attrs = newnv(dev->d_name, NULL, getattr(dev->d_name), 0,
*nvp = nv = newnv(NULL, NULL, NULL, d, NULL);