Re: [PATCH v4 0/9] introduce __pfn_t, evacuate struct page from sgls
From: Dan Williams
Date: Fri Jun 05 2015 - 17:23:50 EST
On Fri, Jun 5, 2015 at 2:19 PM, Dan Williams <dan.j.williams@xxxxxxxxx> 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
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