From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
Subject: Re: Enabling peer to peer device transactions for PCIe devices
Date: Wed, 23 Nov 2016 12:12:15 -0700
Message-ID: <20161123191215.GB12146@obsidianresearch.com>
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On Wed, Nov 23, 2016 at 10:40:47AM -0800, Dan Williams wrote:

> I don't think that was designed for the case where the backing memory
> is a special/static physical address range rather than anonymous
> "System RAM", right?

The hardware doesn't care where the memory is. ODP is just a generic
mechanism to provide demand-fault behavior for a mirrored page table.

ODP has the same issue as everything else, it needs to translate a
page table entry into a DMA address, and we have no API to do that
when the page table points to peer-peer memory.

Jason