AGP_PAGE_SIZE
gatt->ag_size = AGP_PAGE_SIZE + entries * sizeof(u_int32_t);
gatt->ag_virtual = (u_int32_t *)(vdir + AGP_PAGE_SIZE);
gatt->ag_physical = gatt->ag_pdir + AGP_PAGE_SIZE;
gatt->ag_vdir[i] = (gatt->ag_physical + i * AGP_PAGE_SIZE) | 1;
if (agp_alloc_dmamem(pa->pa_dmat, AGP_PAGE_SIZE, &isc->scrib_dmamap,
tmp += AGP_PAGE_SIZE)