Re: [Xen-devel] [PATCH v4 1/6] xen: improve changes to xen_add_to_physmap

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 14 Sep 2012, Jan Beulich wrote:
> >>> On 14.09.12 at 15:56, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> >> > > Might we prefer to have a batched version of this call? I don't think
> >> > > we can shoehorn the necessary fields into xen_add_to_physmap_t though.
> >> > 
> >> > Actually, talking about this we Stefano we think we can. Since both idx
> >> > and gpfn are unsigned longs they can become unions with a GUEST_HANDLE
> >> > without changing the ABI on x86_32 or x86_64.
> > 
> > Except we need both foreign_domid and size, which currently overlap, and
> > there's no other spare bits. Damn.
> > 
> > Looks like XENMEM_add_to_physmap_range is the only option :-(
> 
> You could use the first entry in each array to specify the counts,
> which would at once allow mixed granularity on each list (should
> that ever turn out useful); initially you would certainly want both
> counts to match.

I think it would be better from the interface point of view to have idx
become the number of frames, and gpfn a pointer (a GUEST_HANDLE) to a
struct that contains both arrays.

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