Re: [PATCH] MIPS64: 48 bit physaddr support in memory maps

From: Leonid Yegoshin
Date: Wed May 13 2015 - 18:58:52 EST

On 05/13/2015 02:47 PM, David Daney wrote:
On 05/13/2015 11:55 AM, Leonid Yegoshin wrote:
Originally, it was set to 40bits only but I6400 has 48bits of physaddr.

Why not go to the architectural limit of 59 bits?

Because any physaddr should fit PTE and EntryLo register and we also need 5 or 7 SW bits in PTE.

Even with fixed PTE bits layout from

we need 5 or 7 additional bits, so the real limit is 54. And 54 is actually specified as a limit in EntryLo starting from MIPS R2.
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