Re: [Xen-devel] [PATCH v2 0/2] map grant refs at pfn = mfn

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.07.14 at 19:18, <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> One reason for wanting the second p2m mapping is to avoid tracking mfn
> to pfn mappings in the guest kernel. Since the same mfn can be granted
> multiple times to the backend, finding the right pfn corresponding to a
> given mfn can be difficult and expensive. Providing a second mapping at
> a known address allow the kernel to access the page without knowing the
> pfn.

Since you didn't respond to my earlier respective question: Is this
really the route you want to go? Bake the 1:1-ness into the kernel?
Iiuc this implies no backends using grants in other than Dom0... Or
else you still need to have the M->P tracking code in place, and I
would wonder whether bypassing it is really such a significant win.

Jan


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