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Subject: Re: [PATCH 1/2] xen/granttable: Support sub-page grants
From: Ian Campbell <Ian.Campbell@citrix.com>
To: ANNIE LI <annie.li@oracle.com>
CC: Paul Durrant <Paul.Durrant@citrix.com>,
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Date: Wed, 7 Dec 2011 10:33:56 +0000
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On Wed, 2011-12-07 at 10:27 +0000, ANNIE LI wrote:
> 
> On 2011-12-7 17:57, Ian Campbell wrote:
> > On Wed, 2011-12-07 at 08:59 +0000, Paul Durrant wrote:
> >>> gnttab_v2_ops = {
> >>>    ...
> >>> .access_subpage = access_subpage_v2;
> >>> .access_ref_subpage = access_ref_subpage_v2; .access_trans =
> >>> access_trans_v2; .access_ref_trans = access_ref_trans_v2; }
> >>>
> >>
> >> Do you need ops for the ref and non-ref functions? I would have
> >> thought you could just have the ref ones since the all the non-ref
> >> variants do is allocate and then call the ref variant.
> > Good point. It appears that all the existing ops are only present in the
> > ref form.
> So I will add two elements: access_ref_subpage and access_ref_trans into 
> gnttab_v2_ops.

The existing convention seems to be for _ref to be a suffix, although
it's only actually used on the end_*_ref ones.
+       int (*end_foreign_access_ref)(grant_ref_t, int);
+       unsigned long (*end_foreign_transfer_ref)(grant_ref_t);

Also it occurs to me that access_* sounds like something which uses a
ref rather than something which sets one up. The existing hook to setup
a normal grant is called "update_entry". Perhaps
update_{subpage,transitive}_entry?

Ian.