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[Xen-devel] RE: vbd transfer limits

To: James Harper <james.harper@xxxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] RE: vbd transfer limits
From: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
Date: Fri, 14 Jan 2011 00:52:23 +0000
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  We handle multiple requests per SRB in the Citrix PV drivers so I see no 
issue with this.


> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of James Harper
> Sent: 13 January 2011 14:52
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] vbd transfer limits
> GPLPV provides access to vbd devices via scsiport. I'm writing a
> storport driver now to resolve a couple of limitations under 2008
> and
> newer, and one of the notes says that a storport driver should
> support
> buffers >64KB, but the vbd interface only supports a maximum of 40KB
> (10
> * 4KB) bytes per transfer. If it turns out that this limit is a
> problem
> I will need to break each windows SRB into multiple ring requests.
> As
> long as I honour any write barrier requests from Windows, can anyone
> see
> any problems with this?
> Thanks
> James
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