Re: [PATCH] rdma: don't make pages writeable if not requiested

From: Michael S. Tsirkin
Date: Thu Mar 21 2013 - 14:02:57 EST

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.

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