Message-ID: <53CD443A.6050804@zytor.com>
Date: Mon, 21 Jul 2014 09:47:54 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Toshi Kani <toshi.kani@hp.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org,
        arnd@arndb.de, plagnioj@jcrosoft.com, tomi.valkeinen@ti.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        stefan.bader@canonical.com, luto@amacapital.net, airlied@gmail.com,
        bp@alien8.de
Subject: Re: [RFC PATCH 0/11] Support Write-Through mapping on x86
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On 07/21/2014 09:31 AM, Toshi Kani wrote:
> Do you have any comments / suggestions for this approach?

Approach to what, specifically?

Keep in mind the PAT bit is different for large pages.  This needs to be
dealt with.  I would also like a systematic way to deal with the fact
that Xen (sigh) is stuck with a separate mapping system.

I guess Linux could adopt the Xen mappings if that makes it easier, as
long as that doesn't have a negative impact on native hardware -- we can
possibly deal with some older chips not being optimal.  However, my
thinking has been to have a "reverse PAT" table in memory of memory
types to encodings, both for regular and large pages.

	-hpa


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