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Re: [Xen-devel] Re: Making pages writable again in paging_log_dirty mode

To: Tim Deegan <Tim.Deegan@xxxxxxxxxx>, Mike Sun <msun@xxxxxxxxxx>
Subject: Re: [Xen-devel] Re: Making pages writable again in paging_log_dirty mode
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Fri, 02 Jan 2009 17:38:24 +0000
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On 02/01/2009 17:20, "Tim Deegan" <Tim.Deegan@xxxxxxxxxx> wrote:

> This is all confused further by the fact that the checks for these
> un-type-counted mappings in put_page_from_l1e() doesn't quite match the
> check in get_page_from_l1e(); ISTR there's a difference in the semantics
> of the domain pointer argument to the two functions; maybe Keir can
> refresh my memory.

The checks are the same I think, but indeed the domain argument to
get_page_from_l1e() and put_page_from_l1e() have slightly different meanings
-- the former is essentially a capability, which is checked for permission
to create the given PTE (usually the domain which owns the PTE, unless a
foreigndom is specified to do_mmu_update()), while the latter is *always*
the domain which owns the PTE.

 -- Keir




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