From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH] rdma: don't make pages writeable if not requiested
Date: Thu, 21 Mar 2013 20:03:00 +0200
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To: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
Cc: Roland Dreier <roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, "Michael R. Hines" <mrhines-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Hal Rosenstock <hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Yishai Hadas <yishaih-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>, "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org
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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
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