Date: Tue, 9 Jan 2018 10:10:08 -0700
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Christoph Hellwig <hch@lst.de>
Cc: Logan Gunthorpe <logang@deltatee.com>,
        open list <linux-kernel@vger.kernel.org>,
        linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-rdma <linux-rdma@vger.kernel.org>,
        linux-nvdimm@lists.01.org, linux-block@vger.kernel.org,
        Stephen Bates <sbates@raithlin.com>,
        Jens Axboe <axboe@kernel.dk>,
        Keith Busch <keith.busch@intel.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Max Gurtovoy <maxg@mellanox.com>,
        Dan Williams <dan.j.williams@intel.com>,
        =?utf-8?B?SsOpcsO0bWU=?= Glisse <jglisse@redhat.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 06/12] IB/core: Add optional PCI P2P flag to
 rdma_rw_ctx_[init|destroy]()
Message-ID: <20180109171008.GB4518@ziepe.ca>
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On Tue, Jan 09, 2018 at 05:46:40PM +0100, Christoph Hellwig wrote:
> On Mon, Jan 08, 2018 at 12:49:50PM -0700, Jason Gunthorpe wrote:
> > Pretty sure P2P capable IOMMU hardware exists.
> > 
> > With SOC's we also have the scenario that an DMA originated from an
> > on-die device wishes to target an off-die PCI BAR (through the IOMMU),
> > that definitely exists today, and people care about it :)
> 
> Then people will have to help and contribute support for it.

Sure. But my point was all this will have to migrate under the dma_ops
for that to work, so why the resistance to using dma_ops right away?

Jason