Re: [Xen-devel] [PATCH] libxc: introduce a per architecture scratch pfn for temporary grant mapping

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2015-01-14 at 13:23 +0000, Andrew Cooper wrote:
> > ARM is defining a grant table range which is out of the RAM and not
> > mapped at that time. So we can reuse it with any possible issue.
> 
> Do you mean to say that there is a grant table range baked into the ABI
> occupying guest physical address space?

A range of otherwise unused IPA space is suggested to the guest via the
device tree node, as a convenience for the guest so it doesn't need to
figure one out for itself (it's morally equivalent to the BAR provided
on the x86 platform PCI device).

So the actual address is not part of the guest ABI, but the toolstack
does know what it is going to be since it is privy to some internal
details of the guest layout.

Ian.


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