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Re: [Xen-devel] What actually destroys a domain?


On Sep 13, 2006, at 8:15 AM, Keir Fraser wrote:




On 13/9/06 10:23, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:


Xenconsoled's mapping of the console page should keep the domain
alive.

hmm, I'm having trouble associating the "mapping" and a refcount of
some sort somewhere, any pointers?

See share_xen_page_with_guest() in arch/x86/mm.c. The refcnt is dropped when
xenheap_pages field reduces to zero in
common/page_alloc.c:free_domheap_pages().

Sorry, I'm talking rubbish here. As you say, the relevant code is actually in the foreign mapping paths (e.g., in arch/x86/mm.c). Those paths do a get_page() on the foreign page. This stops it being removed from the domU page list. A non-empty page list holds a reference on the domU. So the domU
will not die until that foreign mapping is destroyed.

Whew!

-JX

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