Second naive question about map operation

[Jean Wolter]

Jean Wolter <jean.wolter at inf.tu-dresden.de> writes:

> So I think this [ unmap a page in a certain address space ] is a
> useful operation.

PS: I forgot a really nasty interaction with grant. If I take the
example of the other thread:

        A
       / \
      B   C

Assuming A doesn't know that B constructed the dependency between A
and C (either using map/grant or co-equal mapping) and A unmaps the
page only in the address space of B there is still the mapping in the
address space of C.

So to make unmap(page, adress space) actually usable you would need a
possibility to prohibit the grant operation for a page.

Regards, 
Jean