VGA_FB_SIZE
if (bus_space_map(memt, 0xa0000, VGA_FB_SIZE, 0, &memh_fb))
bus_space_unmap(memt, memh_fb, VGA_FB_SIZE);
if (bus_space_map(memt, 0xb8000, VGA_FB_SIZE, 0, &memh_fb)) {
bus_space_unmap(memt, memh_fb, VGA_FB_SIZE);