Re: unmap() sometimes unmaps more pages than specified

[Espen Skoglund]
> You have two spaces A and B.  A has a 4MB page mapping.  B has
> received a 4KB page mapping from A.  Currently we have:

>   (1)  A.Flush(4K) == A.Flush(4M) since A has a 4MB mapping.
>   (2)  Likewise A.Unmap(4K) == A.Unmap(4M) since A has a 4MB mapping.
>   (3)  B.Flush(4K) is fine since B has a 4KB mapping.
>   (4)  Consequently A.Unmap(4K) != B.Flush(4K).

> I guess (4) is what you find difficult to handle, right?  This would
> work fine if (2) was not the case.  Currently the implementation
> does (obviously) not behave this way.  I'll give some thought to how
> this could most easily be handled.  The behaviour also raises some
> questions about the semantics of resetting/reading reference bits,
> but I think this could possibly be sorted out.

FYI: Just implemented this a couple of days ago, and Jan has been
pushing this (and a bunch of other updates) to the public.  What we
have now is:  A.Unmap(4K) == B.Flush(4K).

	eSK