Re: [PATCH v7 3/7] powerpc/mm: Introduce _PAGE_LARGE software pte bits
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2016-11-30 00:35:32
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2016-11-30 00:35:32
On Wed, 2016-11-30 at 11:14 +1100, Balbir Singh wrote:
quoted
+#define _RPAGE_RSV1 0x1000000000000000UL +#define _RPAGE_RSV2 0x0800000000000000UL +#define _RPAGE_RSV3 0x0400000000000000UL +#define _RPAGE_RSV4 0x0200000000000000UL +We use the top 4 bits and not the _SW bits?
Correct, welcome to the discussion we've been having the last 2 weeks :-) We use those bits because we are otherwise short on SW bits (we still need _PAGE_DEVMAP etc...). We know P9 DD1 is supposed to ignore the reserved bits so it's a good place holder. Cheers, Ben.