From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir@xensource.com>
Subject: Re: x86 swiotlb questions
Date: Fri, 15 Dec 2006 16:47:59 +0000
Message-ID: <C1A8823F.6278%keir@xensource.com>
References: <4582C365.76E4.0078.0@novell.com>
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To: Jan Beulich <jbeulich@novell.com>, Keir Fraser <keir@xensource.com>
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On 15/12/06 14:46, "Jan Beulich" <jbeulich@novell.com> wrote:

>> Yes, that would be great. There are a couple of minor caveats around special
>> semantics of the Xen heap but those could do with cleaning up and being made
>> explicit anyway.
> 
> Mind adding a little more detail here?

Some allocations need to be below 4GB (e.g., domain pointers, as they get
pickled into a 32-bit field in page structures). These should use an
explicit address-width parameter to the allocator.

Pages allocated from the 'Xen heap' but shared with a domain have special
semantics when their refcount falls to zero. This includes shared_info and
grant-table pages. We may need an extra PGC_ bit to flag these pages.

That's all I can think of.

 -- Keir