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Date: Thu, 21 Mar 2013 20:03:00 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] rdma: don't make pages writeable if not
	requiested
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To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Roland Dreier <roland@kernel.org>, qemu-devel@nongnu.org, "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>, Yishai Hadas <yishaih@mellanox.com>, LKML <linux-kernel@vger.kernel.org>, "Michael R. Hines" <mrhines@linux.vnet.ibm.com>, Hal Rosenstock <hal.rosenstock@gmail.com>, Sean Hefty <sean.hefty@intel.com>, Christoph Lameter <cl@linux.com>

On Thu, Mar 21, 2013 at 11:57:32AM -0600, Jason Gunthorpe wrote:
> On Thu, Mar 21, 2013 at 07:42:37PM +0200, Michael S. Tsirkin wrote:
> 
> > It doesn't actually, and our app would sometimes write to these pages.
> > It simply does not care which version does the remote get in this case
> > since we track writes and resend later.
> 
> Heh, somehow I thought you might say that :)
> 
> A new flag seems like the only way then - maybe:
>   IBV_ACCESS_NON_COHERENT - The adaptor and the CPU do not share
>      a coherent view of registered memory. Memory writes from the CPU
>      after ibv_reg_mr completes may not be reflected in the memory
>      viewed by the adaptor.
> 
>      Can only be combined with read only access permissions.
> 
> Jason

I kind of like _GIFT for name, gifts are nice :) But yes that's exactly
the semantics we need.

-- 
MST