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Date: Fri, 5 Jun 2015 14:23:41 -0700
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Subject: Re: [PATCH v4 0/9] introduce __pfn_t, evacuate struct page from sgls
From: Dan Williams <dan.j.williams@intel.com>
To: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>, Boaz Harrosh <boaz@plexistor.com>,
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On Fri, Jun 5, 2015 at 2:19 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> Introduce __pfn_t which:
>
> 1/ Allows kernel internal DAX mappings to adhere to the lifetime of the
>    the underlying block device.  In general, it enables a mechanism to
>    allow any device driver to advertise "device memory" (CONFIG_DEV_PFN)
>    to other parts of the kernel.
>
> 2/ Replaces usage of struct page in struct scatterlist.  A scatterlist
>    need only carry enough information to generate a dma address, and
>    removing struct page from scatterlists is a precursor to allowing DMA to
>    device memory.  Some dma mapping implementations are not ready for a
>    scatterlist-pfn to reference unampped device memory, those
>    implementations are disabled by CONFIG_DEV_PFN=y.
>
> Changes since v4 [1]:

v3: https://lists.01.org/pipermail/linux-nvdimm/2015-May/000749.html