On Mon, 27 Oct 2014, Toshi Kani wrote: > + } else { > + /* > + * PAT full support. WT is set to slot 7, which minimizes > + * the risk of using the PAT bit as slot 3 is UC and is > + * currently unused. Slot 4 should remain as reserved.
This comment makes no sense. What minimizes which risk and what has this to do with slot 3 and slot 4? > + * > + * PTE encoding used in Linux: > + * PAT > + * |PCD > + * ||PWT PAT > + * ||| slot > + * 000 0 WB : _PAGE_CACHE_MODE_WB > + * 001 1 WC : _PAGE_CACHE_MODE_WC > + * 010 2 UC-: _PAGE_CACHE_MODE_UC_MINUS > + * 011 3 UC : _PAGE_CACHE_MODE_UC > + * 100 4 <reserved> > + * 101 5 <reserved> > + * 110 6 <reserved> Well, they are still mapped to WB/WC/UC_MINUS .... > + * 111 7 WT : _PAGE_CACHE_MODE_WT > + */ > + pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) | > + PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, WT); > + } Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/