WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

RE: [Xen-devel] swiotlb and Xen query?

To: "pradeep singh rautela" <rautelap@xxxxxxxxx>
Subject: RE: [Xen-devel] swiotlb and Xen query?
From: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
Date: Thu, 3 May 2007 11:35:08 +0200
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Thu, 03 May 2007 02:33:53 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <6bc632150705030224w789eca7eu2a279631bf99a316@xxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AceNZQYbv0+olxFNQHOP9gDLRmniyAAAAm9w
Thread-topic: [Xen-devel] swiotlb and Xen query?
 

> -----Original Message-----
> From: pradeep singh rautela [mailto:rautelap@xxxxxxxxx] 
> Sent: 03 May 2007 10:25
> To: Petersson, Mats
> Cc: xen-devel
> Subject: Re: [Xen-devel] swiotlb and Xen query?
> 
> 
> 
> On 5/3/07, Petersson, Mats <Mats.Petersson@xxxxxxx> wrote:
> 
>       [snip]
>       >
>       >
>       > That was really very informative Mats.
>       > Thanks you very much for the help.
>       > So, i guess swiotlb comes into picture only if there is a DMA
>       > transfer from a domU whose p2m mapping turns out to be above 
>       > the 4GB( assuming device to be 32 bit) of the machine memory.
>       > Other wise just normal p2m mapping is enough to find the
>       > actual machine address, which can be handed over to the
>       > device for DMAing. Am i right? 
>       
>       Yes, that's pretty much how it works. In theory, it 
> could be that
>       devices only work on a 31, 28 or some other number of 
> bit-range, but
>       yes, that's the principle.
> 
> 
> Ok.Got this correct. 
> I am sure this can cause problems while migrating live 
> domains across cpus.
> yes/no/thoughts?

Yes, you can't live-migrate (or migrate at all, I think) driver domains,
as there is no way to determine if a driver has outstanding DMA
requests. You need to shut it down and restart it elsewhere if you want
to move it from one machine to another. [Of course not across CPU's, but
if you actually move across physical machine boundary]. 

[I had a quick look, but I couldn't actually find any checks for this,
but I still believe it holds true that driver domains can't be
saved/restored/migrated]. 

--
Mats
> 
> Thank you 
> ~psr
> 
> 
> 
>       --
>       Mats
>       >
>       > Thank you once again for the patience.
>       >
>       > Regards
>       > ~psr
>       >
>       [snip]
>       
>       
>       
> 
> 
> 
> 
> -- 
> ---
> pradeep singh rautela
> 
> "Genius is 1% inspiration, and 99% perspiration" - not me :) 
> 



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>