Re: [Xen-users] IOMMU Domain for Dom0

[Todd Deshane <todd.deshane@xxxxxxx>]

On Wed, Jun 22, 2011 at 1:20 PM, Alex Merritt <merritt.alex@xxxxxxxxx> wrote:
> Hi,
>
> 2011/6/22 sploving <sploving1@xxxxxxx>:
>>
>>
>>
>> AtÂ2011-06-21Â12:17:56ï"AlexÂMerritt"Â<merritt.alex@xxxxxxxxx>Âwrote:
>>
>>>Hello,
>>>
>>>I'veÂbeenÂexperimentingÂwithÂVT-dÂsupportedÂPCI-passthroughÂinÂXenÂfor
>>>HVMÂguests,ÂandÂwasÂwonderingÂifÂitÂisÂpossibleÂtoÂcreateÂanÂIOMMU
>>>domainÂforÂDom0ÂasÂwell.ÂI'mÂnotÂsureÂifÂI'mÂaskingÂtheÂquestion
>>>correctly,ÂbutÂtoÂavoidÂchangingÂaÂbare-metalÂdriverÂforÂanÂI/OÂdevice
>>>toÂtranslateÂsystemÂmemoryÂaddressesÂusedÂbyÂaÂDMAÂengine,ÂwouldÂI
>>>insteadÂbeÂableÂtoÂallowÂtheÂIOMMUÂtoÂtransparentlyÂtranslate
>>>addressesÂjustÂlikeÂforÂguestÂVMs,ÂbutÂwithinÂDom0?
>> why put the IOMMU within Dom0? not in the driver domain?
>
> I'm using research code, which currently requires the management
> extension and driver to exist within the same domain. IOMMUs are meant
> for guest VMs as far as I can tell. They can be used as driver
> domains, too, but (unless I'm mistaken) cannot use the management
> interfaces available in Dom0.
>

To me, this research sounds similar to "InDriver: Using In-VM
Isolation to Implement Drivers" that is going to be presented at the
upcoming Xen Summit

see: http://xen.org/community/xensummit.html

I could be wrong about the relationship, but it does sound like
similar concepts are being explored.


> My driver domain is also Dom0 at the moment.
>
>> ÂSomeÂsearchingÂand
>>>readingÂofÂtheÂwikiÂpagesÂonÂxen.orgÂtellsÂmeÂtheÂanswerÂisÂ"no".ÂBut
>>>IÂcannotÂdetermineÂifÂthisÂisÂpurelyÂbecauseÂtheÂimplementationÂwithin
>>>theÂVMMÂdoesn'tÂexist,ÂorÂbecauseÂitÂisÂthatÂDom0ÂisÂpara-virtualized
>>>andÂthusÂcannotÂuseÂVT-dÂwithoutÂVT-x.ÂI'mÂsuspectingÂitÂisÂnotÂthe
>>>latter,ÂasÂtheÂVTdHowToÂwikiÂpageÂhintsÂPVÂguestsÂmayÂuseÂVT-dÂandÂthe
>>>IntelÂmanualÂforÂVT-dÂdescribesÂOSÂdevelopersÂmayÂtakeÂadvantageÂof
>>>thisÂextension.
>>>
>>>MyÂimmediateÂinterestÂisÂmoreÂtoÂseeÂifÂitÂ"canÂbeÂdone"ÂviaÂaÂhackÂor
>>>something,ÂnotÂnecessarilyÂwhetherÂitÂwouldÂmakeÂsense
>> forÂXenÂto
>>>supportÂthisÂinÂtheÂfuture.
>>>
>> You should ask this question in xen-dev list.
>
> Okay, I'll do that. I'm new to these mailing lists, and wasn't sure
> where to start. Thanks.
>
>>>I'mÂusingÂXenÂ4.1.1ÂandÂpv-opsÂlinuxÂ(notÂupstream)Â2.6.32.40ÂonÂan
>>>IntelÂX5660ÂwithÂa
>> TylersburgÂchipset.
>>>
>>>Thanks!
>>>Alex
>>>
>>>_______________________________________________
>>>Xen-usersÂmailingÂlist
>>>Xen-users@xxxxxxxxxxxxxxxxxxx
>>>http://lists.xensource.com/xen-users
>
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>



-- 
Todd Deshane
http://www.linkedin.com/in/deshantm
http://www.xen.org/products/cloudxen.html
http://runningxen.com/

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