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From: Balbir Singh <bsingharora@gmail.com>
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Date: Fri, 13 Jan 2017 19:27:41 +0530
To: =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, John Hubbard <jhubbard@nvidia.com>,
        Russell King <linux@armlinux.org.uk>,
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        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, Chris Metcalf <cmetcalf@mellanox.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [HMM v16 01/15] mm/memory/hotplug: convert device bool to int to
 allow for more flags v2
Message-ID: <20170113135741.GA26827@localhost.localdomain>
References: <1484238642-10674-1-git-send-email-jglisse@redhat.com>
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On Thu, Jan 12, 2017 at 11:30:28AM -0500, Jérôme Glisse wrote:
> When hotpluging memory we want more informations on the type of memory and
> its properties. Replace the device boolean flag by an int and define a set
> of flags.
> 
> New property for device memory is an opt-in flag to allow page migration
> from and to a ZONE_DEVICE. Existing user of ZONE_DEVICE are not expecting
> page migration to work for their pages. New changes to page migration i
> changing that and we now need a flag to explicitly opt-in page migration.

Given that ZONE_DEVICE is dependent on X86_64, do we need to touch all
architectures? I guess we could selectively enable things as we enable
ZONE_DEVICE for other architectures?

Balbir Singh.