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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Fri, 12 Apr 2019 12:37:16 -0700
Message-ID: <CAPcyv4heZ7+2QuS2YXYsZcU9EOb87MDymfO8-+bLhbPgYQAYJw@mail.gmail.com>
Subject: Re: [PATCH RESEND 3/3] mm: introduce ARCH_HAS_PTE_DEVMAP
To:     Robin Murphy <robin.murphy@arm.com>
Cc:     Linux MM <linux-mm@kvack.org>, "Weiny, Ira" <ira.weiny@intel.com>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        "Oliver O'Halloran" <oohall@gmail.com>, X86 ML <x86@kernel.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Apr 12, 2019 at 12:02 PM Robin Murphy <robin.murphy@arm.com> 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 with the long-out-of-date comment can lead to the impression than an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.

Looks good to me.

Acked-by: Dan Williams <dan.j.williams@intel.com>