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RE: [Xen-devel] Grant Table Hyper Calls For Sharing Memory

To: "Kumar, Venkat" <Venkat.Kumar@xxxxxxx>
Subject: RE: [Xen-devel] Grant Table Hyper Calls For Sharing Memory
From: Daniel Stodden <stodden@xxxxxxxxxx>
Date: Wed, 20 Aug 2008 02:38:53 -0700
Cc: Xen Developers <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On Wed, 2008-08-20 at 16:17 +0800, Kumar, Venkat wrote:
> First of all, we require a hypercall to setup domain's grant table,
> HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
> As you said that sharing a page (to be more precise granting foreign access 
> to a page I think) will be done by setting permissions in the grant table's 
> grant reference structure based on the grant reference number.
> But what is the use of just granting access unless there is a way to map that 
> page from a foreign domain?

A PV domain will. Actually one may argue that this is a predominant
usage pattern.

> My assumption on sharing a page includes offering a page and mapping the page.
> Correct me if I am wrong.

Sorry, I don't know much enough the hvm core. Maybe someone else finds
the comment. 

But I'd guess there's probably more elegant (from a pure HVM
perspective) ways to plug this into the machine. E.g. PCI memory. If
that's not how it presently works, maybe someone should do it.. ;)


Daniel Stodden
LRR     -      Lehrstuhl für Rechnertechnik und Rechnerorganisation
Institut für Informatik der TU München             D-85748 Garching
http://www.lrr.in.tum.de/~stodden         mailto:stodden@xxxxxxxxxx
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