+
+#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
+#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
+#define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
+#else
+#define BIOVEC_VIRT_START_SIZE(x) 0
+#define BIOVEC_VIRT_OVERSIZE(x) 0
+#endif
+