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	Fri, 20 Nov 2015 13:14:57 +0300
From: AlexandreFressange <deco33000@yandex.com>
To: freebsd-amd64@freebsd.org
Subject: PAT and identity mapped pages.
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Hi,

On x86_64, every memory page entry has a bit (4) to control its cache method: write-back or write-through.

But even on identity mapped pages, you still use paging. Say, I want a page to be uncached; I can use the PAT to Uncached.

In this case, what happens to the bit 4 of the accessed page? is it ignored?

Thanks


--š
Alex