Date: Fri, 24 Apr 2015 07:57:38 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Christoph Lameter <cl@linux.com>
Cc: Austin S Hemmelgarn <ahferroin7@gmail.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Jerome Glisse <j.glisse@gmail.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, jglisse@redhat.com, mgorman@suse.de,
        aarcange@redhat.com, riel@redhat.com, airlied@redhat.com,
        aneesh.kumar@linux.vnet.ibm.com,
        Cameron Buschardt <cabuschardt@nvidia.com>,
        Mark Hairgrove <mhairgrove@nvidia.com>,
        Geoffrey Gerfin <ggerfin@nvidia.com>,
        John McKenna <jmckenna@nvidia.com>, akpm@linux-foundation.org
Subject: Re: Interacting with coherent memory on external devices
Message-ID: <20150424145738.GZ5561@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
References: <alpine.DEB.2.11.1504211839120.6294@gentwo.org>
 <20150422000538.GB6046@gmail.com>
 <alpine.DEB.2.11.1504211942040.6294@gentwo.org>
 <20150422131832.GU5561@linux.vnet.ibm.com>
 <alpine.DEB.2.11.1504221105130.24979@gentwo.org>
 <1429756200.4915.19.camel@kernel.crashing.org>
 <alpine.DEB.2.11.1504230921020.32297@gentwo.org>
 <55390EE1.8020304@gmail.com>
 <20150423193339.GR5561@linux.vnet.ibm.com>
 <alpine.DEB.2.11.1504240909350.7582@gentwo.org>
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On Fri, Apr 24, 2015 at 09:12:07AM -0500, Christoph Lameter wrote:
> On Thu, 23 Apr 2015, Paul E. McKenney wrote:
> 
> >
> > DAX
> >
> > 	DAX is a mechanism for providing direct-memory access to
> > 	high-speed non-volatile (AKA "persistent") memory.  Good
> > 	introductions to DAX may be found in the following LWN
> > 	articles:
> 
> DAX is a mechanism to access memory not managed by the kernel and is the
> successor to XIP. It just happens to be needed for persistent memory.
> Fundamentally any driver can provide an MMAPPed interface to allow access
> to a devices memory.

I will take another look, but others in this thread have called out
difficulties with DAX's filesystem nature.

							Thanx, Paul

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