From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <aliguori@us.ibm.com>
Subject: Re: Re: [Xen-devel] VMX Hardware
Date: Sun, 14 Aug 2005 13:09:53 -0500
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To: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
Cc: Goetz Bock <bock@blacknet.de>, xen-devel@lists.xensource.com, xen-users@lists.xensource.com, monz@danbbs.dk
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Keir Fraser wrote:

>
> On 14 Aug 2005, at 13:23, Mogens Valentin wrote:
>
>> I assume by VMX, you're talking about cpu/hardware with HW-support 
>> for virtualisation, i.e. Intels Vanderbilt Technology (VT) and AMD' 
>> Pacifica. If so, it's clear to me that AMD will be leading, because 
>> of it's onchip memory controller, and hence reduced needs for 
>> software support to do the page switching, for which Intel needs 
>> quite a lot of software to emulate.
>
>
> Not sure what you mean. Both technologies require the hypervisor to 
> maintain shadow page tables.

The Pacifica spec does mention optional hardware support for "Nested 
Page Tables" which is essentially hardware shadow page tables.

Should be interesting to see the performance difference between 
software/hardware shadow page tables.

It's worth noting that AMD has just released a simulator for (SimNow) 
that has virtualization support.  Perhaps one of the AMD guys on the 
list can confirm whether SimNow has enough Pacifica support for Xen 
development?

Regards,

Anthony Liguori

>
>  -- Keir
>
>
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