From mboxrd@z Thu Jan  1 00:00:00 1970
From: hch@lst.de (Christoph Hellwig)
Date: Thu, 27 Jun 2019 11:01:54 +0200
Subject: [RFC PATCH 00/28] Removing struct page from P2PDMA
In-Reply-To: <c15d5997-9ba4-f7db-0e7a-a69e75df316c@deltatee.com>
References: <20190620161240.22738-1-logang@deltatee.com>
 <20190624072752.GA3954@lst.de>
 <558a27ba-e7c9-9d94-cad0-377b8ee374a6@deltatee.com>
 <20190625072008.GB30350@lst.de>
 <f0f002bf-2b94-cd18-d18f-5d0b08311495@deltatee.com>
 <20190625170115.GA9746@lst.de>
 <41235a05-8ed1-e69a-e7cd-48cae7d8a676@deltatee.com>
 <20190626065708.GB24531@lst.de>
 <c15d5997-9ba4-f7db-0e7a-a69e75df316c@deltatee.com>
Message-ID: <20190627090154.GA11548@lst.de>

On Wed, Jun 26, 2019@12:31:08PM -0600, Logan Gunthorpe wrote:
> > we have a hole behind len where we could store flag.  Preferably
> > optionally based on a P2P or other magic memory types config
> > option so that 32-bit systems with 32-bit phys_addr_t actually
> > benefit from the smaller and better packing structure.
> 
> That seems sensible. The one thing that's unclear though is how to get
> the PCI Bus address when appropriate. Can we pass that in instead of the
> phys_addr with an appropriate flag? Or will we need to pass the actual
> physical address and then, at the map step, the driver has to some how
> lookup the PCI device to figure out the bus offset?

Yes, I think we'll need a lookup mechanism of some kind.