Subject: Re: Xen3 physical memory map/location for dom0
To: Manuel Bouyer <bouyer@antioche.eu.org>
From: Daniel Carosone <dan@geek.com.au>
List: port-xen
Date: 11/10/2006 10:19:26
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On Fri, Nov 10, 2006 at 12:00:56AM +0100, Manuel Bouyer wrote:
> > Is it something that can be influenced by the ELF headers of the dom0
> > kernel?  I know there were some changes recently (as part of the 3.0.3
> > support) to load addresses and other possibly promising parameters..
>=20
> Actually putting a limit on dom0 memory may not be enough; a network buff=
er
> from a domU can end up in the DMA descriptor of the network adapter

Hm, I suppose so.  Normally this would be a good thing. :-)

Would it matter if the traffic was being bridged vs routed? Probably not.

> > Any other clues?
>=20
> How does the driver deal with this limitation ? Does it work with a plain
> i386 kernel ?

It doesn't.  There have been some unsucessful attempts at a bounce-buffer
style solution in the driver, and some discussion of adding various kinds
of more general "dma constraints" properties, but at present the driver
just fails if used with >1G native.  Both of these ideas would probably get
even more complicated under Xen.

--
Dan.
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