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RE: [Xen-devel] Question about implementation of 32-bit guests on64-bit

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, "Vessey, Bruce A" <Bruce.Vessey@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Question about implementation of 32-bit guests on64-bit hypervisor (IDT-related)
From: "Ian Pratt" <Ian.Pratt@xxxxxxxxxxxxx>
Date: Fri, 7 Dec 2007 15:19:16 -0000
Cc: Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] Question about implementation of 32-bit guests on64-bit hypervisor (IDT-related)
> > (2)  What are the configuration restrictions, if any, for running
32-
> bit
> > guests on top of the 64-bit hypervisor?
> 
> 32-bit PV guests are restricted to using the low 128GB of physical
> memory.
> There's not even that restriction for 32-bit HVM guests.

We could even use shadow translate mode to get around the 128GB
restriction, though at some performance cost. I guess you'd switch the
guest to shadow mode if you've run out of memory below 128GB.

Ian

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