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[Xen-devel] vbd transfer limits

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Subject: [Xen-devel] vbd transfer limits
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Fri, 14 Jan 2011 09:51:39 +1100
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Thread-index: AcuzdHCbuMoX7PhGSQqC2yJ24c5V+Q==
Thread-topic: 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?



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