ENTRY_BITPOS_QWORDS
return ((entry & ENTRY_MASK_QWORDS) >> ENTRY_BITPOS_QWORDS) << 3;
return id << ENTRY_BITPOS_DESCRIPTOR | qlen << ENTRY_BITPOS_QWORDS;
(((1 << ENTRY_BITS_QWORDS) - 1) << ENTRY_BITPOS_QWORDS)