vr_desc_t
vr_desc_t *wp;
vr_desc_t *rxp;
vr_desc_t *wp;
vr_desc_t *cp;
(vr_desc_t *)kmem_zalloc(n * sizeof (vr_desc_t), KM_SLEEP);
kmem_free(r->desc, n * sizeof (vr_desc_t));
vr_desc_t *rp;
vr_desc_t *desc;
vr_desc_t *ring;
vr_desc_t *wp; /* write pointer */
vr_desc_t *cp; /* claim pointer */
vr_desc_t *ring;
vr_desc_t *rp; /* read pointer */