RF_UL
RF_ASSERT(((RF_UL(dst) | RF_UL(a) | RF_UL(b) | RF_UL(c) | len) & 0x7) == 0);
#define RF_BLIP(x) (PAGE_SIZE - (RF_UL(x) & RF_PGMASK)) /* bytes left in page */
#define RF_PAGE_ALIGNED(x) ((RF_UL(x) & RF_PGMASK) == 0)