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Subject: Re: [PATCH RESEND 3/3] mm: introduce ARCH_HAS_PTE_DEVMAP
To:     Robin Murphy <robin.murphy@arm.com>, linux-mm@kvack.org
Cc:     dan.j.williams@intel.com, ira.weiny@intel.com, jglisse@redhat.com,
        oohall@gmail.com, x86@kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-kernel@vger.kernel.org
References: <cover.1555093412.git.robin.murphy@arm.com>
 <25525e4dab6ebc49e233f21f7c29821223431647.1555093412.git.robin.murphy@arm.com>
From:   Anshuman Khandual <anshuman.khandual@arm.com>
Message-ID: <cc96cad8-2078-8ee0-9ce7-d073dcc702c8@arm.com>
Date:   Mon, 15 Apr 2019 17:00:35 +0530
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On 04/13/2019 12:31 AM, Robin Murphy wrote:
> ARCH_HAS_ZONE_DEVICE is somewhat meaningless in itself, and combined
> with the long-out-of-date comment can lead to the impression than an
> architecture may just enable it (since __add_pages() now "comprehends
> device memory" for itself) and expect things to work.
> 
> In practice, however, ZONE_DEVICE users have little chance of
> functioning correctly without __HAVE_ARCH_PTE_DEVMAP, so let's clean
> that up the same way as ARCH_HAS_PTE_SPECIAL and make it the proper
> dependency so the real situation is clearer.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>