Re: [Xen-devel] [PATCH v8 10/14] xen/common: move the memory_mapping DOMCTL hypercall to common code

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2014-05-26 at 12:03 +0100, Julien Grall wrote:
> In any case, I don't think we should expose mfn_t and _mfn to ARM. All 
> the P2M interface used in common code, take an unsigned long in parameter.

I don't object in principal to the idea that common code should be
moving towards more semantic types (i.e. mfn_t rather than unsigned
long) in general. Or even to going as far as x86 has done in the common
code and having mfn_t be more than a typedef (it's a wrapping struct for
type safety), which results in the _mfn() and mfn_x() conversion things.

But I don't think we should be making that transition as part of this
series.

I think the right answer here and now is for map_mmio_regions to take
the mfn as an unsigned long and for the wrapping into a mfn_t to happen
in the x86-specific implementation of map_mmio_regions etc.

That would also get rid of this sort of thing from the previous patch:
         _mfn(mfn_x(mfn) + i))

If someone wants to come along later and "type-safe-up" the common code
too, well, lets think about that then...

Ian.


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